First screen, captured 5 days ago. Open the video.

ZapFast: A fast, native WhatsApp client in Rust and egui

What HN thinks

A slick Rust WhatsApp client, admired briefly before everyone remembered Meta's ban hammer and egui's appetite for redrawing the whole window every frame.

Unofficial clients risk account bans
Many commenters say they won't use it because WhatsApp may suspend accounts on unofficial clients, and they criticise Meta for locking down its APIs.
Immediate-mode egui is wasteful
Some argue that redrawing the whole UI every frame wastes power and runs badly without a GPU, for example in VMs. Others reply that egui apps run fine on modest hardware.
200 MB idle RAM is too much
Commenters contrast it with old multi-protocol IM clients that used a few MB, and say Qt apps manage under 100 MB.

Consensus: Most agree that the ban risk makes unofficial WhatsApp clients hard to recommend, however well they perform. Several also say these clients lack enough features that users end up back in the browser.

Recommended in the comments

Slint (library): Cited as a GUI toolkit with excellent performance and low resource use, even without a GPU.
FLTK (library): Cited as performing well with very little resource use, even without a GPU.
iced (library): Listed as a non-immediate-mode alternative to egui.
Qt (library): One commenter says simple Qt apps on KDE stay well below 100 MB of RAM.

Summarised by Claude from the comment thread 5 days ago.

Points: 87
Comments: 59
Best rank: #3
Posted: 2026-11-08 by handfuloflight
Category: Open source

rust egui whatsapp desktop-app messaging cross-platform

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