ZapFast

WhatsApp, native and fast. ZapFast is a WhatsApp client written in Rust with egui. It uses whatsapp-rust for the WhatsApp Web protocol. It runs on Linux, macOS, and Windows, links to your phone as a companion device, and has no browser engine. In our Linux test, it opens in under a second and uses about 200 MB of idle RAM, compared with 1.13 GB for WhatsApp Web and its Chromium processes. See the measurements.

ZapFast is a sibling of Spotifast, with the same native UI for a different service.

See zapfast.rocks for downloads and guides.

What it does

• Links to your phone. Scan a QR code or link with your phone number. Recent history is copied to this computer after linking and stored here.
• Chats. See pinned, unread, muted, and archived chats, typing indicators, and message status. Search chats, saved messages, and contacts. The Search icon in a chat's header (or Ctrl+F) opens a pane beside the chat, as in WhatsApp Desktop, listing its matches newest first with the time and the line that matched. The calendar narrows them to one day, or lists that day's messages when the field is empty. Clicking a result, or reaching it with the arrow keys and pressing Enter, brings it into view with a brief flash; Escape closes the calendar, then the pane. The pane can be dragged wider, and in a narrow window it lies over the conversation instead of squeezing it. The newest 80 matches are listed, and the pane says when there are more. Right-click a group or a followed channel and choose Leave group or Leave channel to leave it, with the option to archive it in the same step; the local history stays on this computer and the chat keeps its messages. Filter the list to unread, private (one-to-one), favorites, or group chats with the chips under the search bar; a chip with unread chats shows how many it has. Right-click a chat and choose Add to favorites to mark it. Favorites sync with your phone both ways, and the Favorites chip lists them in the phone's order below any pinned chats. A chat added here goes to the end of the list; channels cannot be favorites. Followed channels have their own Channels chip and stay out of the other filters; right-click it to mute or unmute every channel at once. Archived opens the archived chats. Right-click a chat and choose Mark as unread to put an empty dot on it, as on the phone; the mark syncs with your phone both ways, and opening the chat or a new message clears it. Opening a chat with unread messages scrolls to an "unread messages" divider above the first one. Pinned chats stay in pin order (most recently pinned first), regardless of new messages. Like on the phone, you can pin up to three chats. Chat and contact name searches ignore accents, so Angel finds Ángel. The filters stay on one row and scroll horizontally in narrow sidebars. Unnamed groups use a shared participant summary for their title and subtitle; repeated first names appear as Andrea ×3, with your own entry shown as You. Incomplete group metadata preserves known names and retries with backoff; an empty cached subject remains eligible for recovery. Typing indicators show other participants, excluding your own linked devices. Newsletter channels are read-only; publishing channel posts is not supported.
• Account privacy. Settings, Privacy shows who can see your last seen, online status, profile photo, and About, who can add you to groups, your account read receipts, and whether unknown callers are silenced, and changes them on your phone, so a change applies on every linked device. A category set to My contacts except shows as such; the people it excludes are chosen on the phone. The values are read when ZapFast connects and when Settings opens; without a connection they cannot be changed.
• Read state across devices. Reading a chat syncs its unread badge with your phone and other linked devices, including when read receipts are off. Replies from another device clear preceding unread messages. The read-receipt toggle also controls voice-message played receipts; account privacy is checked before sending receipts in direct chats. A hidden window does not read messages.
• Conversations. See replies, reactions, edits, deleted messages, read receipts, sender names, and group pictures. Older messages load as you scroll up, first from the local archive and then from your phone. Group messages show two gray checks after every recipient has received them, and blue checks after every recipient has read them. The recipient list and individual receipts are saved locally; later membership changes do not change that list. If the original recipients are unknown, ZapFast waits for the phone's aggregate status instead of guessing from one reader. A message that could not be sent says "Not sent" beside its time. ZapFast does not retry it; send it again yourself. Timestamps follow the system's 12-hour or 24-hour clock: the time format on Windows and macOS, and GNOME's clock format or the time locale (LC_TIME) on Linux. Select in a message's menu, or Ctrl-click (Command-click on macOS) on a message, starts a selection: click more messages to add or remove them, Shift-click to add everything up to the one you click, then Forward… sends them together, in their original order, or Escape cancels.
• WhatsApp formatting. Bold, italic, strikethrough, code, lists, quotes, mentions, and link previews are supported. Links are clickable. Hebrew, Arabic, and mixed lines follow the Unicode Bidirectional Algorithm, so numbers, punctuation, and embedded words stay in reading order and brackets face the right way. As in WhatsApp, a message whose first strong character is Hebrew or Arabic is aligned to the right, with its time on its own line when the text has more than one. Carets and copied text stay on the logical message. Emoji use the bundled Noto Color Emoji on macOS and Windows. On Linux, ZapFast prefers an installed Noto Color Emoji and falls back to the bundled copy. Emoji-only messages are larger.
• Readable text. Secondary text in the built-in light and dark themes reaches WCAG AA contrast. Inside message bubbles, times, ticks, and other grey text adjust to the bubble's colour, in custom themes as well.
• Screen-reader access. AccessKit exposes the interface to desktop accessibility services. Custom buttons, chat rows, settings switches and message text include readable labels. Windows NVDA navigation still needs platform verification; keyboard and screen-reader support is not complete. In the chat view, Tab cycles through the message input, send/voice button, the plus menu, emoji, profile, sidebar toggle, New chat, Settings, search, and chat filters, then returns to the input. Shift+Tab reverses that order; hidden controls are skipped. Messages, reactions and chat rows are not stops in this cycle; Alt+Up/Down switches conversations. Menus, dialogs and Settings keep their own Tab navigation. Every focus border is a single one-pixel inset outline following the control's shape, including circular voice buttons. Text fields stay outlined while active; other outlines hide when you use the mouse. Focus stays below menus, dialogs, and toasts.
• Safer desktop opening. Links open only web pages or email addresses. Common documents and media open in their default apps; executable, script, and unrecognized attachment formats open their containing folder instead.
• Use interactive messages. Business templates and button messages show their image above the text and their options in separate rows below the timestamp. Reply buttons send the selected option with a quote of the original message. Simple lists open a choice dialog, web links open in your browser, and copy-code buttons copy to the clipboard. Unavailable actions have a phone icon and an explanation. Lists group choices by section, with descriptions and keyboard support. Carousels show separate cards in a horizontal strip, with images, web links, and copy-code actions. Short carousels keep the timestamp beside their last card. When more cards are offscreen, overlaid previous/next arrows move one card at a time. Shift + mouse wheel and horizontal touchpad scrolling also work over the cards, without a bottom scrollbar. Their text can be selected, copied, and searched. Images use the same download, retry, and automatic-download setting as photos. Previously unsupported messages are recovered from the local archive when their original message is available and they have not been edited, without relinking. Other embedded attachments and templates containing only a reference to server-side text still need the phone.
• Errors stay readable. Confirmations such as "Copied" fade after a few seconds. Error messages stay above the composer until you dismiss them, and a button copies their text for a bug report. A repeated error replaces its earlier copy, and only the three newest are kept.
• Send attachments with captions. Paste a picture, drop files, or choose Send files from the plus menu. They stay in the composer until you send them or press Escape. Pasting a picture uses its image data without adding the source URL or HTML to your caption. Text-only clipboard contents still paste as text. MP3, M4A, AAC, and OGG files go as audio messages; other audio, such as WAV or FLAC, goes as a document so the recipient gets the original file.
• Mute chats for eight hours, one week, or indefinitely. The setting also applies on your phone and to desktop notifications. Mute changes from your phone survive history arriving later, including during initial linking. Existing installations request one settings refresh after upgrading to recover previously lost mute settings and pin order, without relinking.
• Delete chats. Remove a chat and its messages from the chat list's right-click menu. The phone deletes it first, so this needs a connection, and the chat only leaves this computer once the phone has confirmed. Chats you delete or clear on the phone disappear here as well, and history that was already on its way does not bring them back.
• Voice messages. Play, seek, record, reply with, and send voice messages in the chat. The speed chip cycles between 1x, 1.5x, and 2x, and the message menu offers 1x, 1.25x, 1.5x, 1.75x, and 2x, keeping the speaker's pitch; the last choice applies to later messages. When one ends, playback carries on through the voice messages right after it that you have not heard yet, as on the phone; any other message ends the run. The app normalizes quiet recordings and handles OGG/Opus without external tools. On Linux and Windows, music and other media playing in other apps pause while you record or play a voice message, or watch a video with sound, and resume afterwards; only players that were playing are resumed. Two switches in Settings turn this off for recording and for playback. Linux uses MPRIS, so any player that implements it works; macOS has no public API for this, so the switches are hidden there.
• Send messages. Press Enter to send text and Shift+Enter for a new line. You can swap these keys in Settings. The composer is focused when you open or return to a conversation; invoking search keeps focus in search, and Escape clears search and returns to the composer; another Escape closes the chat and saves your text draft. Drafts are kept in the encrypted archive, so unsent text survives closing ZapFast and restarting. Open menus, dialogs, and unfinished actions are dismissed first. Type :name to autocomplete an emoji without leaving the composer, or @ in a group to mention a member. Reply, react with any emoji, edit, forward, delete, and check when a message was sent, delivered, or read. Replies can be text, attachments, voice messages, stickers, or GIFs. A reply never goes out without its quote: if the original is no longer available on this computer, nothing is sent, the text or attachments return to the composer, and a voice message waits above it to be sent again or discarded. Cancel the reply to send without a quote. Quotes carry a bar and name in the quoted person's colour; clicking one scrolls back to the original, which flashes briefly, as a search result does. The same right-click menu copies a message's ID, which helps when looking one up for a bug report. Opening a message's context menu outlines that message until the menu closes. The full reaction picker stays beside the menu and adds a target preview. The conversation stays still while you choose; the emoji grid can scroll. Quick reactions learn from usage on this computer, independently of inserted emoji. These preferences do not sync from the phone. Hovering a message also shows a small smiley control beside it; clicking it opens the full reaction picker for that message, so right-click is never required.
• Disappearing-message timers. Outgoing messages use the chat's known timer, including replies, attachments, edits, and forwards. Forwarded copies use the destination chat's timer. Received messages remain in the local archive after they expire on the phone. A clock badge on chat avatars shows enabled timers and follows changes from the phone. Changing the default timer for new chats leaves existing chats alone.
• View attachments. ZapFast downloads files up to 64 MiB automatically or on click. Photos, stickers, GIFs, voice messages, audio, locations, contacts, polls, and link previews appear in the chat. Click a downloaded JPEG, PNG, WebP, or GIF photo to preview it in ZapFast with fit and zoom controls, or choose Open externally. Click a video to play it in its message, with sound, a seek bar, and a mute switch; round video messages play inside their circle with a progress ring, like on the phone. A video that is not downloaded yet downloads first and then plays. Videos in codecs other than H.264, such as HEVC, open in your system player, and so does Open in system player in a video's right-click menu. Unsupported pictures and documents keep opening in their default desktop apps. Save as… in a downloaded attachment's right-click menu keeps a copy wherever you choose, starting in your Downloads folder. Profile pictures and downloaded images support Windows drive paths and filenames with spaces or non-ASCII characters. If an attachment has expired, ZapFast asks your phone to upload it again. Downloads stop after two minutes with an inline retry error if they cannot finish; the menu disables Download while one is running. Cached attachment filenames use extensions of at most 16 ASCII letters, digits, or hyphens; invalid or empty extensions are saved as .bin.
• Polls. Choose Create poll from the plus menu beside the message field to create a poll with 2–12 answers. Turn off Allow multiple answers for a single-choice poll. Click an answer in a poll to vote; click a selected answer again to remove it. Each option shows a result bar and a checkmark for your selection. Show votes lists participants and vote times, updating as votes arrive. Results and your selection are retained in the encrypted archive, including votes received through phone history. New polls received live start at zero votes without asking the phone for earlier results. Polls from history or offline delivery automatically request earlier votes when visible. Until a usable snapshot arrives, results are labelled incomplete and requests retry with backoff; no refresh button or relinking is needed. Voting needs the original poll's key; if that key is missing, the message explains that voting is available on your phone. Creating polls in disappearing-message chats is not yet supported by the protocol library's poll API, so ZapFast blocks it instead of ignoring the timer.
• Emoji, GIF, and sticker picker. Search emoji and GIFs, use recent emoji and stickers, and add stickers to Favorites with a right-click. Favorites sync with your phone both ways, and Recent holds only stickers you sent. Emoji autocomplete and picker search select their first match; use the arrow keys and Enter to choose it. GIF search needs a free GIPHY API key unless the build includes one.
• Sticker packs. A tab strip like WhatsApp's holds Recent, Favorites, and every pack. Search stickers by emoji, by a word that names one, or by pack name. Import a pack from a signal.art link or .wastickers file, or make your own packs from any sticker with a right-click. Open WhatsApp sticker packs shared in a chat and add them, or send any of your packs as one. Turn any picture into a sticker: crop it square, keep its transparent background, and tag it with emojis. Animated packs remain animated. Packs are stored as WebP files on your computer.
• Consistent names. Use names from your address book or public WhatsApp profile names across chats, replies, mentions, and notifications.
• Groups. See members, sender names, and sender pictures. Announcement groups are read-only for non-admins. Clicking a chat.whatsapp.com invite link shows the group's name, size, and description, and joins it (or sends a join request when admins approve members) without leaving ZapFast.
• Presence. See online, last-seen, and typing status, and send your typing status. Like WhatsApp Web, ZapFast shows you as online only while its window is focused, and goes offline ten seconds after you switch away or hide it to the tray, so your phone keeps receiving notifications meanwhile.
• Idle rendering. History-sync progress updates when data arrives. Animated stickers and GIFs show a still first frame and play while hovered in the focused window, keeping idle conversations from continuously repainting.
• Sync recovery. A conflicting app-state collection is recovered through whatsapp-rust, including requesting a fresh snapshot from the paired phone when validation fails. Private read-state updates run one at a time. Failures pause the whole queue with backoff from 30 seconds to 15 minutes; pending reads remain saved and resume automatically. New messages can still arrive.
• Reconnects after sleep. After the computer wakes from sleep, or when the connection has received nothing for two minutes, ZapFast reconnects and fetches what arrived meanwhile, instead of waiting on a connection that looks open but no longer delivers.
• Runs in the background. Closing the window keeps ZapFast linked in the system tray. Reopen it from the tray or by launching it again. Quit from the tray or with Ctrl+Q, or disable this behavior in Settings. The window reopens where you left it; on Windows and X11, one that would open on no connected monitor (for example on a display that is now unplugged) moves to the middle of the primary monitor.
• Start at login. Turn on Start at login in Settings to start ZapFast in the tray when you log in, without opening a window. It adds ~/.config/autostart/zapfast.desktop on Linux, a LaunchAgent in ~/Library/LaunchAgents on macOS, or a Run entry for your user on Windows, and removes it when turned off. zapfast --start-hidden does the same by hand; it opens the window anyway when no tray is available. The Flatpak does not offer this setting yet.
• Desktop notifications. Get notifications with the chat picture when you are away from the open chat. Muted chats do not notify you, and archived chats stay quiet until you unarchive them. Windows notifications identify ZapFast as the sender and show chat pictures as small circular icons; installed and portable builds register this identity in the current user's registry. On Linux and Windows, clicking a notification opens the chat at the message it announced. On Linux, reading the chat here or on another device dismisses its outstanding notifications. On macOS, notifications use the installed ZapFast application's identity without an application chooser; unregistered development builds skip notifications if that identity is unavailable. Sounds follow Pidgin: Message sound plays for every new message, in chats and groups alike, and Mention sound when someone in a group mentions you or replies to one of your messages. Each can be Pidgin's classic message sound (the default for messages), its alert (the default for mentions), the system's notification sound, no sound, or an audio file (WAV, MP3, or OGG Vorbis) that ZapFast plays itself. Turning off Play sounds for group messages keeps group notifications silent unless they mention or answer you. Notification sound in a chat's right-click menu gives that chat its own sound for every message in it, mentions included, stored in the encrypted archive.
• Unread count on the taskbar. On Linux, ZapFast publishes the unread total through the Unity Launcher API, so KDE Plasma shows it as a badge on the taskbar icon, with Show badges enabled in the Task Manager settings. Other launchers that implement the same API, such as GNOME's Dash to Dock or Dash to Panel and the Plank dock, show it too. Clearing chats lowers the count, and zero removes it.
• Update notices. ZapFast checks GitHub once a day and shows a download link when a newer release is available. You can turn this off in Settings.
• Themes. Light, dark, follow the system, or a local JSON palette. Native Linux packages can follow Omarchy colors without restarting the app. Zoom with Ctrl+plus and Ctrl+minus.
• Copy text. Select part of a message or copy across messages in WhatsApp's [time, date] Name: format. Contact names and numbers are also selectable, with Brazilian numbers shown as (DDD) XXXX-XXXX or (DDD) XXXXX-XXXX.
• Keyboard shortcuts. Ctrl+K or Ctrl+Shift+F searches your chats, Ctrl+F searches the open chat as in WhatsApp (↑/↓ walk the results and Enter jumps to one; with no chat open it searches your chats, and in Settings it searches the settings), Alt+↑/↓ switches chats and keeps the active chat visible in the list, ↑ in an empty input edits your previous message, Esc cancels the current action, Ctrl+L focuses the message input, Ctrl+N opens New chat, Ctrl+B hides or shows the chat list, and ? (outside text fields) or Ctrl+/ opens Keyboard shortcuts (use Command instead of Ctrl on macOS). The × at the left of the shortcut hints hides the bar; restore it with Show shortcut hints in Settings.
• Collapsed chat list. Turn on Collapse the chat list to icons in Settings and hiding the chat list leaves a narrow column of avatars instead. It shows the same chats as the full list under the current filter, with unread badges (dimmed for muted chats); hovering names a chat, clicking opens it, and Ctrl+B brings the full list back.
• Local storage. Messages, contacts and sticker metadata are stored in a SQLCipher-encrypted archive, unlocked automatically through your OS keyring. Existing plaintext archives are migrated on first use. Attachments remain ordinary files in the cache directory. Unlinking deletes both and removes this device from your phone.

What it does not do yet

• Play videos in codecs other than H.264 in the app (they open in your system player).
• Calls, status posts, communities, newsletters, and group administration.
• Submit interactive forms, payments, shopping flows, or carousel selections. Use these in WhatsApp Web or on your phone. Embedded videos and documents, and templates without readable text also need another client.

Installing

On macOS with Homebrew: brew install --cask crmne/tap/zapfast.

ZapFast was previously called FastsApp. Version 0.13.0 introduces the new package and executable names. On Arch Linux:

yay -S zapfast-bin      # the released build, ready made
yay -S zapfast          # the release, built from source
yay -S zapfast-git      # built from the latest commit

With Nix, install the package directly from its flake:

nix profile install github:crmne/zapfast

NixOS configurations can add the repository as a flake input and include inputs.zapfast.packages.${pkgs.system}.default in environment.systemPackages.

Builds for every release are on the releases page:

On macOS, the rounded Dock icon matches the app bundle. Native menus provide Settings, editing, search, view controls, and window commands. The traffic lights share the chat header, leaving more room for conversations in a normal window. Settings is also available with ⌘,.

The macOS release process signs the app with Developer ID, submits the DMG to Apple's notarization service, and staples and validates its ticket before publishing. Open the DMG and drag ZapFast to Applications. When upgrading from FastsApp on macOS, quit the old app and remove its application bundle after installing ZapFast.

Releases before 0.13.0 keep their original FastsApp filenames.

Flatpak

Flatpak packaging lives in packaging/flatpak/, following Spotifast's source manifest and release-bundle setup. Future releases will attach an x86_64 .flatpak bundle; install a downloaded bundle with flatpak install --user FILE and run flatpak run rocks.zapfast.ZapFast. Flathub publication is pending; ZapFast is not yet listed there. See PACKAGING.md for local builds and preparing a Flathub submission. File selection uses desktop portals; the sandbox has no general access to your home directory.

Archive encryption

The archive key is a random 256-bit secret in Secret Service on Linux, Keychain on macOS, or Windows Credential Manager. Linux needs a working Secret Service provider (for example GNOME Keyring or KeePassXC with Secret Service enabled). If the keyring is locked or unavailable, unlock it and click Retry; ZapFast keeps its archive intact and waits before connecting. It never saves a replacement plaintext archive. Back up both the archive and its OS keyring key: copying only archive.db to another computer is insufficient.

A missing key is different from a locked keyring. If ZapFast says the key is missing, restore the original OS credential store or use the original profile location. Do not delete the archive or create replacement credentials: neither can decrypt the existing archive. If the original key cannot come back, Start over… on that screen renames the unreadable archive to archive-unreadable-<date>.db beside it, forgets the linked session, and shows the linking screen: linking again brings recent history back from your phone. Remove the old ZapFast entry under Linked devices on the phone afterwards. For help, report the OS, app version, whether the profile was moved/restored, and the error text with personal paths removed. Never attach the archive, keys, or full logs from older releases.

Only archive.db and its SQLite journal/WAL are encrypted. Device credentials in session.db, downloaded media, profile pictures, favorite sticker files and settings remain ordinary files. Use full-disk encryption for those files, swap, backups and remnants of the old plaintext archive. Migration removes the original only after verifying its encrypted copy; deletion cannot guarantee erasure from SSDs or snapshots. Keyring unlocking also does not protect against software running as you while your login is unlocked.

From source

ZapFast needs Rust, a C/C++ toolchain, CMake and Perl (for bundled OpenSSL). rust-toolchain.toml pins the exact version. On Linux, it also needs GUI development packages:

# Debian and Ubuntu
sudo apt install libxkbcommon-dev libwayland-dev libgl1-mesa-dev libasound2-dev cmake perl
# Arch
sudo pacman -S libxkbcommon wayland mesa alsa-lib cmake perl

Then:

cargo install --path .
zapfast

With Nix, nix develop provides the pinned Rust toolchain and all native build dependencies. From the checkout, use nix build .#zapfast to build the package or nix run .#zapfast to run it.

The desktop file and icon are in packaging/.

whatsapp-rust is pinned to a Git commit because version 0.7.0 on crates.io enables a simd feature that needs nightly Rust. The pinned commit builds on stable Rust and includes the upstream fixes for missing app-state snapshots and conflicts that make no progress. ZapFast does not reset your session to recover a collection.

Using it

On first start, scan the QR code from WhatsApp under Linked devices, Link a device. To link without the camera, click Link with phone number instead, enter your number with its country code, then enter the shown code on your phone.

WhatsApp then sends your recent history. This can take a few minutes. A banner shows the progress. New messages arrive live, and your phone does not need to stay on the same network.

Right-click a chat or message to open its menu. Double-click beside a message, or on its edge, to reply to it (a double-click on its text still selects the word). Open Settings from the gear or with Ctrl+,. The pencil opens New chat, with Message yourself and + Add contact at the top, followed by searchable contacts. Add contact also lets you message a new number without saving it. You can also open a group member's contact card. Saved names sync through WhatsApp to your phone and linked devices.

Locked chats

Lock chat in a chat's right-click menu moves the chat into a locked folder: it disappears from the chat list, search, and the unread badge, and its messages never raise a desktop notification. The lock state syncs with your phone and other linked devices.

Choose Locked beside the other chat filters, type your local code, and press Enter or choose Open locked chats. The tab appears when locked chats exist, without a count or names before opening. If no local code exists, it offers to set one up. The local code is separate from your phone's code and is a visibility control, not an extra encryption layer. Search inside the open tab filters its chats. Leaving it, changing or clearing the code in Settings, or closing the window hides the locked chats and closes any open locked conversation. Typing the code into ordinary search remains an alternative way in. Revealed locked chats are currently read-only: sending messages and forwarding into them remain disabled.

After linking or upgrading, chats wait up to ten seconds for WhatsApp's lock state before appearing. Chats already known to be locked stay hidden. If the lock state cannot be confirmed in time, the chats appear with a notice that chats locked on the phone may show until they sync, and recovery keeps retrying in the background. The recovered state is saved in the encrypted archive for offline use.

Protocol logs omit private payloads and raw error details, including verbose logging. Panic logs record the source location without the panic payload. Pairing signature failures and rate limits retain a diagnostic category.

Offline previews for these states use --demo --demo-page channel, --demo --demo-page locked, --demo --demo-page locked-open, and --demo --demo-page keyring. The open locked-folder preview uses demo-code. Use --demo-page locked-prompt, locked-setup, new-chat, unnamed-group, or react-picker for the new dialogs, shared group summaries, and reactions.

The protocol dependency includes the upstream WhatsApp Business pairing fix. Device-store migration waits until an updated window is acknowledged, preserving startup rollback; an unused legacy column is retained for 0.14 compatibility.

Interactive messages

Business messages keep their image, formatted text, timestamp, and options together in one bubble. Reply buttons immediately send the selected response, quoting the original message so the business can recognize your choice. Simple list buttons open a centered dialog with sections, descriptions, and a full-row selection target; choosing an item sends that response. Hover highlights the full action row, following the card edges. Link buttons open your browser, and copy-code buttons copy the offered code locally.

Carousels retain separate cards and images in a horizontally scrollable strip. Each card can open web links or copy codes; reply, calling, and shopping actions that require an unsupported carousel envelope stay unavailable.

Reply buttons require a connection and a writable conversation. They pause while sending, and become available again if the send fails. Actions with a phone icon are unavailable in ZapFast; use WhatsApp Web or your phone. Hovering explains which restriction applies. Replies from other devices retain their quotes too.

Text and reply options	Image and website link

Carousel cards	Poll participant details

These screenshots use synthetic offline chats. See the usage guide for download behavior and the remaining limitations.

Finding a setting

The search field at the top of Settings narrows the page to the settings whose name or description contains what you type, ignoring case and accents, and hides sections with nothing left. A match on a section's name keeps the whole section. Translated settings are found in the interface language and in English. Ctrl+F on the Settings page focuses the field, and Esc clears it.

Interface language

Settings > Appearance > Language chooses the interface language. Auto follows the operating system's language and falls back to English when ZapFast has no translation for it. Brazilian Portuguese, German, Spanish, Italian, French, and Russian cover the chat list, search, composer, shortcut hints, Settings section titles, and dates. Translations are compiled from gettext PO files at build time, with no runtime parsing or network access. Message contents, contact names, logs, and protocol errors are never translated, and copied messages keep WhatsApp's [time, date] Name: format.

Proxy

Settings > Network > Proxy sends the WhatsApp connection, media, profile pictures, GIF search, Signal sticker imports, and update checks through a proxy. It accepts socks5h://host:port (the proxy resolves names, as Tor expects), socks5://host:port, and http://host:port, each with an optional user:password@. A bare host:port is an HTTP proxy. Changing it reconnects at once. When the field is empty, ZapFast uses ALL_PROXY or HTTPS_PROXY from the environment and honors NO_PROXY.

Files

macOS and Windows use the standard platform directories selected by the directories crate. On first start, ZapFast moves settings, the linked session, message archive, favorite stickers, caches, and window state from fastsapp (or the earlier fastwhatsapp) paths. Existing ZapFast directories take precedence and are never overwritten. Quit FastsApp before starting ZapFast; if an older copy is still running, the new launch brings its window forward. Your phone may keep showing the old linked-device name until you link again.

On Linux and macOS, ZapFast restricts its configuration, state, and cache directories to the current user (0700), including existing installations. Startup stops if those directories cannot be created or secured, before opening logs or databases. Windows uses the permissions inherited from your user profile.

Local themes

Settings → Appearance → Theme uses the same picker as Spotifast, with Follow system, Light, Dark, and its Catppuccin, Catppuccin Latte, Nord, Ristretto, Tokyo Night, Rose Pine, Rose Pine Moon, and Rose Pine Dawn palettes. Choose Open themes folder below the picker to add JSON palettes beside settings.json. A local file with a bundled palette's name overrides it. For example:

{"base":"dark","colors":{"accent":"#89b4fa","bubble_out":"#293954"}}

Unspecified colors inherit the light or dark base. Spotifast palettes also work: chat backgrounds, bubbles, and links derive from their interface colors when not specified. Color names match Palette in src/theme.rs; use #RRGGBB or #RRGGBBAA. The last accepted palette is cached in settings, so a missing or damaged theme file does not reset your appearance. Linux watches the themes folder for changes without periodic repaints. On other platforms, use zapfast reload-themes after editing. The command also works while the window is closed and never launches a stopped app.

Settings → Appearance → Wallpaper offers WhatsApp's light and dark wallpaper colours, with a live preview of the selected colour and doodles. Add doodles controls only the SVG layer, so disabling it leaves the selected background colour in place. Light and dark selections are stored independently, and the embedded SVG is rendered at its native size and repeated across the conversation without stretching.

On Omarchy, Follow system and Omarchy read the active desktop palette and follow its changes in native, portable, and source builds, even without installed hooks. Other desktops keep their normal light/dark system preference. Native packages additionally register a missing per-user template and theme hook on first launch; existing user files are preserved. Flatpak uses the desktop's light/dark preference and does not read host theme files or install desktop hooks.

Updating ZapFast

ZapFast checks GitHub once a day when Check for updates is enabled. Click Update in the banner to download and verify a newer release, then Restart to update when convenient. Download updates automatically is optional and off by default; it downloads in the background and still waits for you to restart. Downloads contact GitHub's API and release-asset hosts and are checked against the release's SHA-256 checksums. Before downloading a package, the updater verifies the checksum manifest's Ed25519 publisher signature using its embedded public key. Missing or invalid signatures stop the update. The updater keeps a backup and restores it if the updated app cannot start. Release builds also carry GitHub provenance attestations, independently verifiable with gh attestation verify FILE -R crmne/zapfast. See update signing for key custody and recovery.

The in-app updater supports marked portable downloads, the Windows installer, and the macOS app in Applications. Keep zapfast-portable.txt beside a portable executable. AUR, DEB, RPM, Flatpak, Cargo and Homebrew installations use their package manager. Older portable downloads without the marker need one manual upgrade. No account or additional service is needed.

Developing

cargo run --features demo -- --demo            # sample chats, no connection
cargo run --features demo -- --demo-page login # or settings, pair, info, light, …
cargo run --features demo -- --demo-shot shot.png --demo-page chat,light
cargo run --features demo -- --demo-tour      # Space starts/replays a 41-second tour
cargo run --features demo -- --demo-hover 900,400 # holds a fake pointer there
cargo test --all-features                      # includes a headless layout of every screen
cargo clippy --all-targets --all-features -- -D warnings

To include a default GIPHY key for GIF search, set it at build time. A key in Settings overrides it:

ZAPFAST_GIPHY_KEY=your-key cargo build --release

The earlier FASTSAPP_GIPHY_KEY build variable remains supported as a fallback.

AGENTS.md describes the architecture and the rules for changes. CI checks the complete lockfile against RustSec advisories with cargo audit. Candidate-specific manual checks and results are tracked in the release PR.

Recording a demo

The demo feature uses offline sample chats in a fresh temporary directory. It does not open your linked account, read your message archive, connect to WhatsApp, or register a tray icon. You can run it alongside your regular app.

cargo build --locked --features demo
./target/debug/zapfast --demo-tour --demo-size 1280x800

The ZapFast Demo window waits for Space. The 41-second tour starts with search, switches chats with keyboard shortcuts, scrolls, right-clicks a message and selects Reply, types quickly, completes emoji and mentions, searches the GIF picker and sends a still sticker, opens group information and the shortcut list, and changes themes through Settings. It uses the normal mouse and keyboard handlers; a local responder handles outgoing messages with no WhatsApp connection. The GIF-search thumbnails and still stickers are rendered from the bundled Noto emoji font; demo GIF search uses these local fixtures. The tour makes no sound and holds its final frame. Space rebuilds the sample and replays. For an automatic start, add --demo-tour-delay 5000 (milliseconds). Use --demo instead of --demo-tour to explore the sample chats yourself. Use --demo-page rtl-self for a self-chat of mixed Hebrew, Arabic, and English lines. Use --demo-page composer-tools to preview the WhatsApp-style composer pill and its attachment and poll menu. typing, mention, and emoji-complete preview the multiline field and inline suggestions. Use --demo-page chat-menu to preview the compact chat context menu, and --demo-page chat,voice,voice-menu for a voice message's menu with its speeds. --demo-page video shows a video and round video messages, and video-playing or note-playing starts one of them, silently. For deterministic theme screenshots, --demo-page settings,omarchy and --demo-page settings,omarchy-light preview following dark and light Omarchy palettes without changing the desktop theme.

Use --demo-page interactive for text and button messages, or --demo-page interactive-media for messages with an image, and --demo-page interactive-list for a list message, --demo-page interactive-list-dialog for its grouped choice dialog, --demo-page carousel for a scrolling strip or --demo-page carousel-pair for two cards, and --demo-page poll-empty, poll-voted, or poll-results for voting states. Use --demo-page interactive-actions for reply, list, copy-code, and unavailable form actions. Add ,light to preview any of these in the light theme. Capture the app's own frame without desktop content:

./target/debug/zapfast --demo --demo-page interactive-media --demo-shot interactive.png
./target/debug/zapfast --demo --demo-page interactive-media,light --demo-shot interactive-light.png

On Omarchy, run omarchy screenrecord, select the demo window, then press Space in ZapFast. Recording has no audio unless you explicitly enable desktop or microphone audio. Stop with omarchy screenrecord --stop-recording after the tour finishes. The default capture records a fixed rectangle, so keep the demo window visible and stationary until recording stops.

To annotate the video with a visible pointer, click rings, and outlined shortcut labels, add --demo-tour-events tour.json when launching the tour. After recording, run:

python3 scripts/render-demo.py recording.mp4 tour.json launch.mp4 --start 0.8

Set --start to the recording time (in seconds) when you pressed Space. The export trims the setup footage, adds a caption band below the app, and produces a silent H.264 MP4. It requires ffmpeg with libass support and ffprobe. These annotations are added during video export, not drawn by the app. The trace contains only pointer coordinates and shortcut labels, not typed text.

Disclaimer

ZapFast is an unofficial client and is not affiliated with WhatsApp or Meta. Using an unofficial client may be against WhatsApp's terms of service and could get an account suspended. Use it at your own risk.

Packaging maintenance

Release packaging uses the native-packages gem. macOS release builds automatically sign and notarize when the Apple CI credentials are configured. native-packages.yaml declares packages and downstream repositories; native recipes and installation assets live in packaging/; see PACKAGING.md for local commands and CI behavior.

License

MIT. Inter and Noto Color Emoji are under the SIL Open Font License; the icons and the chat wallpaper doodles are from Lucide (ISC). The notification sounds are Pidgin's, under the GPL-2.0 (see assets/sounds/).