One person rewrote the WhatsApp desktop app: ZapFast hit 3000 stars in two months
What it is A WhatsApp desktop client written in Rust with no bundled browser engine, running on Windows, Mac and Linux. Free and open source.
Why it took off Meta switched the Windows WhatsApp app to a web wrapper that eats 1–2GB of RAM, and people had been complaining for ages. The author used the "150MB vs 1.13GB" comparison, launched through his own X followers and his sister project Spotifast, and in early November Windows Latest named it, with multilingual outlets and repost accounts picking it up.
BHow you could follow Stop building another WhatsApp. Pick a different big-company desktop client that people call bloated and that has an open-source protocol library you can use, rewrite it natively, post the memory comparison and a 40-second video on X on day one, and proactively send it to Windows media and European tech sites.
- Data (updated daily) · Repo created 2026-08-29 · 3,346 stars · 7 days +1,019
GitHub · stars Data 2026-09-25 → 2026-11-08 (45 days, 32 observations). Points before 10-28 come from deeply / archive backfill, not every day has one
Meta replaced the Windows WhatsApp app with a web shell that eats 2GB of RAM. Italian developer Carmine Paolino wrote a native version in Rust that uses one-fifth of the memory. It's called ZapFast, the repo is 69 days old, it has 3,092 stars, and it gained 799 in the last week. Below: how it earned those stars, and which parts you can copy if you want a project that gets the same traction.
A 40-second video and two numbers
In the afternoon of Sep 15, 2026, Paolino posted on X: "I built ZapFast⚡ A native WhatsApp client in Rust for Linux, macOS & Windows". The post came down to two numbers: on his Linux machine, ZapFast used 150MB of RAM, while WhatsApp Web plus Chromium needed 1.13GB; the chat UI appeared in 0.7 seconds, versus about 4 seconds for the web version. He added an install command yay -S zapfast-bin and a 40-second demo video.
The post got 45.3k views and 843 likes (X page, 11-06). The top reply was "Bro is going to rebuild every electron app now in rust xd", and someone said "I just installed the native Spotify client (Spotifast) on my computer and now there's a native WhatsApp too?!". The same day he posted again: "I rewrote the two Electron apps I use most in native Rust: Spotify ➡️ spotifast.rocks, WhatsApp ➡️ zapfast.rocks. We can fix everything."
What it is
A WhatsApp desktop client with no bundled browser engine, running on Windows, Mac and Linux. MIT-licensed, free. It logs into your WhatsApp account as a companion device, the same way scanning a QR code for WhatsApp Web does, and messages are stored only on your own computer, never passing through any third-party server.
It ships fast. Built in Aug 29, it pushed a dozen-plus versions the next day; by early November it was at v0.21, with voice messages, stickers, polls, multiple accounts, encrypted local storage, and app lock. The Oct 23 0.20 release added voice and video calls, one-on-one and in groups, which Linux users never had before.
The protocol layer isn't the author's work; it uses the open-source whatsapp-rust library (1,006 stars). What he did was package it into a product that ordinary people can install and use every day.
Why now
The pain point was created by Meta itself. In November 2025, Meta replaced the native Windows WhatsApp app with a WebView2 wrapper, and memory use jumped from around a hundred-odd MB to 1–2GB. Daring Fireball criticized it at the time, and Windows Latest wrote several pieces about it over the year. A post on Reddit's r/pcmasterrace had the title "WhatsApp is one of the worst apps on Windows 11, eating 2GB of RAM". The Mac version has always been native from Meta, while Linux has no official client at all.
So ZapFast didn't have to explain why it exists. "WhatsApp uses too much RAM" was already a common complaint. Download numbers show it: GitHub Releases total about 79k downloads, of which the Windows installer is about 40k, Linux about 28k, and Mac about 11k (GitHub, 11-06). The biggest chunk of users are not Linux enthusiasts but ordinary Windows users whose computers the new WhatsApp slowed down. On Mac the official app already works well, so it has the fewest downloads.
Where the stars came from
In chronological order:
| Timeline | What happened | star |
|---|---|---|
| 09-15 | The author's X launch, and the German tech site stadt-bremerhaven wrote about it the same day | — |
| 09-25 | Small European outlets and developers on LinkedIn picked it up and reshared it one after another | 836 |
| From ¥10-01 | Omarchy (DHH's Arch desktop) crowd picks up ZapFast: works with Omarchy themes | — |
| 10-23 | 0.20 can make calls, another round on X and Show HN | 2,094 |
| 11-01 | Windows Latest rips the official app for eating 2GB of RAM, names ZapFast at the end | 2,327 |
| 11-03 to 11-05 | Czech, Russian and Chinese tech sites repost in bulk, repost accounts follow | 2,412 → 2,785 |
| 11-06 | Single day +307 | 3,092 |
(stars from GitHub daily snapshots; the 09-25 figure comes from web archives)
A few forces at work:
The author's own reputation. Paolino wrote RubyLLM, a Ruby library. His account has 15 repos totaling nearly 20k stars. Sister project Spotifast was created two days before ZapFast and now has 9,755 stars. Both READMEs and websites link to each other, and both sit on the same fastframe framework, so anyone who installs one is likely to install the other.
Numbers you can use as headlines. "150MB vs 1.13GB" and "0.7 seconds vs 4 seconds" were copied almost verbatim in nearly every repost. Media and repost accounts could use them directly without testing anything themselves.
The Windows Latest piece. Nov 1, the headline read "I uninstalled the worst Windows 11 app, the WhatsApp that eats 2GB of RAM." Halfway through it cut to a ZapFast segment with video, and the last line was "If one developer can build a native WhatsApp client, what excuse does Meta have left?" Growth picked up noticeably in the two days after it ran.
Repost accounts. On 11-04, X repost account @rammcodes posted "What a time to be alive 😂🔥 Someone really built…", getting about 11k views and 242 likes. The same copy also appeared on a public Facebook page and on Reddit's r/BestGitHubRepos.
A round with every update. 0.16 and 0.20 each got video posts on X and Show HN. Hacker News barely responded: the three Show HN posts scored 2, 4 and 5 points. HN was not its channel.
Distribution was broad too: Homebrew, AUR, Nix, Flatpak, AppImage, deb, rpm, msi, and the Mac build is notarized. Windows users who don't touch the command line can install it with one click, which is why Windows accounts for about half of downloads. No sign of paid promotion turned up.
It is also upfront about the risk: the site says "using unofficial clients may violate WhatsApp's terms of service and could get your account banned." In a Nov 3 HN thread the author said there had been 65k downloads in two months and no reports of bans.
Who's competing for this spot
| Project | star | How it differs |
|---|---|---|
| WhatsApp official Windows app | Hundreds of millions of users | WebView2 wrapper, 1–2GB of RAM |
| WhatsApp official Mac app | Big | Already native, so ZapFast's edge on Mac is small |
| Ferdium | 4.8k | Multiple chat apps stuffed into one Electron shell, heavier |
| nchat | 2.0k | Terminal UI, only for hardcore users |
| ZapZap | 1.7k | PyQt web wrapper for Linux |
| WasIstLos | 1.2k | WebKitGTK web wrapper, unmaintained since 2024 |
| Altus | 715 | Electron wrapper, supports multiple accounts |
| oxidezap/client | 39 | Nearly identical stack, can also make calls, but nobody promotes it |
| Aggregator IM like Beeper | Big | Messages go through its bridge server |
(stars on GitHub, 11-06)
Existing GUI clients are almost all browser wrappers. ZapFast is the first native one you'd actually use every day. The one to watch is oxidezap/client: its builder is the author of the whatsapp-rust protocol library, and on launch day Paolino replied with the link, saying he'd "been building something similar for a while." The tech is nearly identical, one has 3000 stars, the other has 39. What separates them is distribution and polish, not technical barriers.
Others are already following
- yapfast (created 10-16, 187 stars): "A Discord client without the web browser. Native, written in Rust." The name and copy were lifted directly.
- zaptide (09-22,43 stars): "a fast, native WhatsApp client in Rust, GTK4 and Libadwaita", nearly word for word the same description.
- Same approach: native Discord client Serein (1,016 stars), plus YouTube Music clients ytm-rs and refryt.
The author shows no sign of stopping. On LinkedIn he wrote "Building 5 Rust native apps (Spotifast, ZapFast, +3)."
If it were you
B: worth a try. The play of "pick a big-company client that people call bloated, rewrite it natively, and market a memory comparison" works, and many apps still have no native rewrite. The weak spot: the WhatsApp slot is taken, copycats are getting only a few dozen to a hundred or two stars, and you don't have the author's reputation or a sister project to funnel traffic.
Who it suits: developers who can write native UI in Rust, Swift or C++ and ship releases frequently for months; ideally someone with an already-known project or some X following.
Who it doesn't suit: anyone building another native WhatsApp, Spotify or Discord. All three already have fast-moving versions. Also anyone who only wants a working demo and doesn't plan to maintain it, since stars here come from people using it every day.
How to do it: first pick a target that meets three conditions: a large base of desktop users; an official app built on Electron or a web wrapper that people are complaining about now; and an open-source protocol or library already available (like whatsapp-rust, since reverse-engineering from scratch is nearly impossible). Apply those filters to chat, music and note-taking apps beyond Teams, Slack and Telegram (which one is best is unverified; start by checking who Reddit and Windows media are bashing right now). Then follow its sequence: measure memory and startup time in the first version and turn it into a headline sentence; make a 40-second demo video; ship a Windows installer, Homebrew and AUR on day one; state the ban or terms-of-service risk up front in the README; and do another round with video for every major feature. If you plan a second or third app, use one brand and one underlying framework so they feed each other.
How to get users: launch on X with video and comparison numbers. Then send the comparison data directly to outlets like Windows Latest and Neowin that specialize in "this Windows app is terrible" pieces, along with German, Czech and Russian tech sites. That is where ZapFast's biggest wave came from. Hacker News is worth posting to, but don't expect much.
Timing: the approach works right now because "Electron is bloated" plus "in the AI era one person can rewrite big-company software" is exactly what developers are excited to share. Once native rewrites become common enough to feel stale, repost accounts and media will stop covering them. That's probably half a year to a year away (inference). For a specific app, the window closes when the official team returns to native, or when it starts banning third-party clients.
Signs you're reading it wrong: (1) WhatsApp begins mass-banning accounts that use third-party clients and ZapFast's stars stall. That would mean rewriting someone else's client is too risky, and later entrants should pick platforms with official APIs. (2) Copycats like yapfast and zaptide stay under a few hundred stars while Paolino's next three apps each hit thousands right away. That would mean the approach depends on the author's reputation and doesn't work for people without one. (3) Conversely, if someone without a reputation rewrites a different app with the same playbook and passes 1,000 stars in a month, the approach works for anyone.
Research notes: competitor table, acquisition evidence, full research report
- Competitors
Name Where Launched Scale How it differs from this one WhatsApp official Windows app Big-company features 2025-11 changed to WebView2 Hundreds of millions of users Browser wrapper, 1–2GB of RAM; ZapFast about 200MB WhatsApp official Mac app Big-company features Already available (native via Catalyst) Big The official Mac app is already native, so ZapFast's edge there is small and it gets the fewest downloads WhatsApp Web Web 2015 Big Opens a browser; the author measured about 1.13GB ZapZap Open source 2022 1,693 star PyQt6 + WebEngine wrapper WasIstLos(whatsapp-for-linux) Open source 2020 1,163 stars, unmaintained since 2024 WebKitGTK wrapper, no longer maintained Altus Open source 2018 715 star Electron wrapper Ferdium / Rambox Open source From ¥2017 Ferdium 4.8k star Electron shell aggregating multiple services, heavier nchat Open source 2019 2,021 star Terminal UI, only for hardcore users oxidezap/client Open source 2026-08 39 star Nearly identical stack (Rust + whatsapp-rust + GPUI, and can make calls), but no distribution push Aggregator IM like Beeper Other Already around Big Routes through a bridge server; ZapFast connects directly and locally, with no third-party server - Where users come from
- Verified Author's own X launch + demo video: 09-15 @paolino launched it with 45.3k views and 843 likes, and posted a Spotifast + ZapFast series the same day
- Verified Sister project Spotifast cross-linking: Spotifast has 9,755 stars; the READMEs and websites link to each other and share the fastframe framework. Traffic from the link is unverified.
- Verified Tech media coverage: Windows Latest 2026-11-01 article names ZapFast; also stadt-bremerhaven (09-15), zive.cz, devtrends.ru (11-04), earlysignal (11-03), zidrave (10-06)
- Verified X / Facebook / Reddit repost accounts: @rammcodes 11-04 post got about 11k views and 242 likes; the same copy appeared on a public Facebook page; r/BestGitHubRepos has a repost
- Verified Omarchy / Arch Linux crowd: supports following Omarchy themes, listed by omarchyarchive 10-01; the launch command is yay -S zapfast-bin
- Verified Hacker News: 3 Show HN posts scored 2, 4 and 5 points; the impact was small
- Guess Paid ads: no evidence found
Why ZapFast (crmne/zapfast) took off
In short: a native WhatsApp desktop client written in Rust with egui, with no bundled browser engine (Linux / macOS / Windows), MIT-licensed and free. Author: Carmine Paolino (RubyLLM author, X @paolino).
Verdict
It took off because three things hit at once. First, Meta swapped Windows' native WhatsApp for a WebView2 wrapper in 2025-11, and memory went from about 100MB to 1–2GB, while Linux never got an official client. The "WhatsApp eats memory" grievance had been argued over on Windows Latest, Daring Fireball and Reddit for a full year. Second, the author had distribution ready made: the sister project Spotifast (9.8k stars) and the X followers from RubyLLM, with the launch tweet at 45k views, and the README and website funneling into each other. Third, the product came with a number you could put in a headline: "200MB vs 1.13GB." The acceleration from 11-03 to 11-06 came from a Windows Latest piece 11-01 (naming ZapFast directly), followed by a wave of reposts from multilingual tech outlets and aggregator accounts starting 11-04. The differentiation (native, no browser shell, calling on Linux, multiple accounts) is why it ran, but it's easy to copy, and people already are.
Data
- stars: 2026-09-25 836 (wayback) → 10-09 1,716 → 11-02 2,347 → 11-04 2,462 → 11-05 2,785 (+323) → 11-06 3,092 (+307). The GitHub API queried live shows 11-06 3,220. Source: our github library repo_day; data card gain_7d 799, prev_7d 199.
- Downloads (sum of download_count across GitHub Releases versions, queried live 11-06): Windows installers about 40.4k, Linux about 27.6k, macOS about 10.6k, roughly 79k in total. This doesn't count AUR, Homebrew, or Nix. checksums.txt was downloaded about 23.6k times, likely because in-app updates check it, so it can be read roughly as a signal of active installs (unverified). The author said on HN 11-03 "2 months, 65k+ downloads, no ban reports so far".
- Windows is the biggest download platform, which suggests the real users aren't Linux enthusiasts but Windows users burned by the WebView2 version of WhatsApp.
- Iteration was fast: 08-29 the repo was created, and 08-30 saw a dozen-plus releases in one day. By 11-03 it had reached v0.21.1; 0.20 (10-23) added 1:1 along with group voice and video calls.
- Money: free, MIT license. The author opened GitHub Sponsors and has 10 sponsors (this is the count across the author's whole account, not just this project). There is no paid tier.
Competitors
| Name | Where | Launched | Scale | How it differs from ZapFast |
|---|---|---|---|---|
| WhatsApp official Windows app | Big-company features | 2025-11 switched to a 2 WebView | Hundreds of millions of users | Browser wrapper, 1–2GB of RAM (Windows Latest measured over 2026-11-01 2GB); ZapFast about 200MB |
| WhatsApp official Mac app | Big-company features | Native Catalyst | Big | The official Mac app was already native, so ZapFast gets the fewest downloads there (about 10.6k) |
| WhatsApp Web | Web | 2015 | Big | Needs a browser tab; the author measured 1.13GB |
| ZapZap(rafatosta/zapzap) | Open-source Linux | 2022 | 1,693 star | PyQt6 + WebEngine wrapper |
| WasIstLos / whatsapp-for-linux | Open-source Linux | 2020 | 1,163 stars, unmaintained since 2024 | WebKitGTK wrapper |
| Altus | Open source | 2018 | 715 star | Electron wrapper, supports multiple accounts and themes |
| Ferdium / Rambox / Franz | Open source / commercial | From ¥2017 | Ferdium 4.8k star | Electron shell aggregating multiple services, heavier |
| nchat | Open-source TUI | 2019 | 2,021 star | Terminal UI, built on whatsmeow, aimed at power users |
| Karere | Open-source Linux | 2023 | 221 star | GTK4 + WebView |
| oxidezap/client | Open source | 2026-08 | 39 star | Also Rust, built on the same protocol library (made by the whatsapp-rust author team), with a GPUI interface and calling support, but no distribution, so almost nobody knows about it |
| Aggregator IM like Beeper | Commercial | Already around | Big | Goes through a bridge server; ZapFast connects directly from the local machine, "Nothing goes to a server of ours" |
The underlying protocol library is oxidezap/whatsapp-rust (1,006 stars, created 2025-07), modeled after whatsmeow (Go, 7.8k) and Baileys (TS, 11.5k). ZapFast didn't write the protocol. It did the productizing and distribution.
Where users come from (by time)
- The author's own X launch (confirmed): 2026-09-15 @paolino posted "I built ZapFast⚡ … 150MB RAM vs 1.13GB … ~0.7s vs ~4s" with a demo video, 45.3k views and 843 likes. The same day he posted "I rewrote the two most-used Electron apps as native Rust apps: Spotify ➡️ spotifast.rocks, WhatsApp ➡️ zapfast.rocks. We can fix everything." Sources: x.com/paolino/status/2099867212232142937, 2099873542363849092.
- Cross-promotion from the sister project Spotifast (confirmed cross-links exist; referral traffic not verified): Spotifast's repo was created two days before ZapFast's. By 11-06 it had 9,755 stars and 10-07 made the HN front page (41 points). The two projects' READMEs and websites link to each other, and both are built on the fastframe framework.
- European tech outlets picked it up (confirmed): 09-15 stadt-bremerhaven.de (German), netguide.io; 10-06 zidrave.net (Spanish); 10-17 the Kubuntu forum; listed on alternativeto.net; developers in Turkey and Azerbaijan reshared it on LinkedIn (09-19).
- The Omarchy community (confirmed): the app can follow Omarchy desktop themes, and omarchyarchive.com 10-01 archived "ZapFast Follows Omarchy Themes". The author is part of the Ruby community, which overlaps heavily with DHH's Omarchy users, and the launch command was Arch's
yay -S zapfast-bin. - Feature milestones used as promo material (confirmed): 0.16 (09-24) and 0.20 calling support (10-23) each got a post on X and a Show HN. HN itself responded weakly: the 3 submissions scored 2, 4, and 5 points, so HN isn't a real channel here.
- The trigger for the 11-03–11-06 acceleration (confirmed, timing matches):
- Windows Latest 2026-11-01 published "I uninstalled Windows 11's worst app, the 2GB RAM-eating WhatsApp". The article name-checks ZapFast at the end and embeds a video ("if one developer can build a native WhatsApp client, what's stopping Meta?").
- 11-03 earlysignal.news; 11-04 zive.cz (Czech), devtrends.ru (Russian), autoxb.com (Chinese), and a review at mrkeyoor.com; 11-05 ai.lzw.me (Chinese).
- 11-04 aggregator account @rammcodes posted "What a time to be alive 😂🔥 Someone really built…", about 11k views and 242 likes. The same copy also appeared on a public Facebook page, and Reddit's r/BestGitHubRepos has a repost ("2.6k stars").
- Background mood: r/pcmasterrace on Reddit has a thread titled "WhatsApp is one of Windows 11's worst apps, eating 2GB of RAM".
- No paid ads, TikTok, or Product Hunt campaigns turned up (searching zapfast in the local X corpus x-radar returns 0 results, so coverage is incomplete).
Why it's working
- Timing, i.e. the platform event: Meta 2025-11 dropped the native Windows app in favor of a WebView2, and over the course of a year memory use rose from about 600MB to over 2GB. Windows Latest wrote article after article about it (2025-11, 2026-06, 2026-11). So ZapFast didn't have to educate users. "WhatsApp uses too much RAM" was already a known pain point. Windows accounting for about half of downloads is the evidence.
- Comparison numbers that work as headlines: "200MB vs 1.13GB" and "0.7 seconds vs 4 seconds". Nearly every repost copied this pair of numbers verbatim, and media and aggregators could use them as-is.
- Built-in distribution from the author: X followers from RubyLLM and Spotifast, plus the series narrative of "rewriting Electron apps as native one by one" ("We can fix everything"). It matches the mood against Electron bloat and the idea that one person in the AI era can rewrite big-company software.
- The product works and iterates fast: over two months it shipped more than 20 versions, with voice messages, stickers, polls, multiple accounts, encrypted local archives, export, and app lock. Calling arrived 0.20 and filled the gap on Linux that the official client never covered and third-party clients couldn't fill either. Every feature added was another chance to get promoted.
- Distribution channels covered end to end: Homebrew cask, AUR, Nix, Flatpak, AppImage, deb, rpm, msi, and the macOS build is notarized (the author also open-sourced a packaging tool, native-packages). Ordinary Windows users can install it in one click.
- Risks stated openly: the README and website say up front that it "may violate WhatsApp's Terms of Service and may get accounts banned". The author said on HN that after two months and 65k downloads there were no ban reports. Users' concerns were addressed directly in the comments.
Differentiation
Every existing option wraps a browser (the official WebView2, the web version, Electron / PyQt / WebKit shells), or it's a TUI. ZapFast is the first graphical native WhatsApp client that's usable day to day (no browser engine, memory down to a fifth), and on Linux it supports calls and multiple accounts. That differentiation is why it ran, because the promo material was the "native vs browser" memory comparison. But the moat is shallow: the protocol library is open source whatsapp-rust, and whatsapp-rust's author is building a similar client themselves (oxidezap/client, 39 stars). That suggests distribution and polish will decide the outcome, not technical exclusivity.
How many people saw it, and who's copying it
- Visibility: it's spreading in small circles and is expanding outward. There's coverage from European, Russian, Czech, and Chinese tech outlets and Windows Latest, plus aggregator accounts, but no big account (100k+ followers) or major English-language outlet has covered it specifically. There's no public revenue, because it's free.
- Copycats: yapfast/yapfast (created 10-16, 187 stars, "A Discord client without the web browser. Native, written in Rust", with the name and copy following the same pattern); luminusOS/zaptide (09-22,43 stars, "ZapTide: a fast, native WhatsApp client in Rust, GTK4 and Libadwaita", with a description nearly copied word for word); other "Rust-native rewrites of Electron clients" include Serein (native Discord, 1,016 stars), ytm-rs, and refryt (YouTube Music). The author himself says he's building 5 such apps (LinkedIn: "Building 5 Rust native apps (Spotifast, ZapFast, +3)").
What others can borrow
- Find an app where a big company replaced the native client with a web wrapper and users are angry about it, rewrite it natively, and use a measurable comparison (memory / startup time) as the promo material.
- Build it as a series (one xxxfast.rocks brand + the shared fastframe framework): each new app promotes the others.
- Cover every packaging channel at once so non-developers can install it. The real volume is on Windows, not Linux.
- Treat every feature update as a new promotional moment (an X post with video + Show HN).
Unknowns
- Whether WhatsApp cracks down on third-party companion devices or changes its protocol (the biggest risk).
- It's impossible to separate how much of the +323 stars on day 11-05 came from Windows Latest, aggregator accounts, and Reddit respectively.
- Actual active users (release downloads and checksum requests are only rough proxy metrics).
- Whether the author plans to monetize (the author's company Plenty has other products; this may just be brand and capability showcasing).
Sources
- github.com/crmne/zapfast (README, Releases API, checked live as of 11-06)
- Our GitHub repo_day (crmne/zapfast, crmne/spotifast)
- x.com/paolino/status/2099867212232142937 ;x.com/paolino/status/2099873542363849092 ;x.com/paolino/status/2113688004720250919
- x.com/rammcodes/status/2117803625644994577
- www.windowslatest.com/2026/11/02/i-uninstalled-windows-11s-w…
- daringfireball.net/2025/11/meta_whatsapp_windows_shitty_web_…
- news.ycombinator.com/item?id=50357326, 50212897, 49843111; HN 49990730 (Spotifast)
- stadt-bremerhaven.de/zapfast-schlanker-open-source-client-fu… ;www.zive.cz/clanky/whatsapp-pro-pocitace-ktery-zabere-jen-zl… ;devtrends.ru/rust/crmne-zapfast ;earlysignal.news/s/crmne-zapfast ;omarchyarchive.com/posts/paolino-zapfast-omarchy-themes/
- www.reddit.com/r/BestGitHubRepos/comments/1xodpnz/ ;alternativeto.net/software/zapfast/about/
- Competitor stars: GitHub API, checked live as of 11-06