Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by jedbrooke on Saturday November 07, 2026 @11:24PM
(#50410398)
It’s really a shame that all of these unofficial clients are like this. APIs are APIs, if they’re on the public internet why can’t anybody call them? If there’s potential for abuse then that should be secured server side anyway, since needing a unofficial client isn’t going to stop hackers
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by dvdyzag on Sunday November 08, 2026 @01:51AM
(#50411008)
Eventually the unofficial client gets "fingerprinted" and its over. Its easy to remove the suspension, though. I vaguely remember it was through email.
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by qingcharles on Sunday November 08, 2026 @02:02AM
(#50411055)
Eh, there's no humans any longer IIRC. It's all down to whether their support AI blesses you or not.
I got banned for trying to move my chats from Android to iOS using the app rather than the special tool I didn't know you were supposed to use. I was lucky I eventually got unlocked.
I want a decent WhatsApp client that doesn't crash constantly and where you can search properly, but it's not worth the risk of getting banned again.
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by cowlevel on Sunday November 08, 2026 @01:36AM
(#50410954)
I actually wish they'd delete the warning so then anyone who gets banned from WhatsApp for using an unofficial client would have a more legit cause of action against WhatsApp. Meta wouldn't be able to defend themselves with "well you were warned" if you weren't warned.
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by darccio on Sunday November 08, 2026 @03:01AM
(#50411287)
I think this doesn't apply to European users, as WhatsApp announced around one year ago that under Digital Markets Act they were required to allow interoperability with third party providers [0].
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by LoganDark on Sunday November 08, 2026 @07:16AM
(#50412608)
Someone would probably unironically say "you should've made your friends over XMPP then". I tend to get that when commenting about Nvidia support - "you should've bought your hardware for Linux then".
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by codedokode on Saturday November 07, 2026 @11:50PM
(#50410495)
Egui is pretty bad idea. It uses "immediate mode" rendering which means whole window is redrawn on every mouse move. I ran PhotoCraft (built in Rust + egui) in a VM wihout a GPU and the UI felt like it was running on 3 fps.
Egui is definitely not what you want to use on a 4K screen. It is only good for tiny screens of embedded devices.
Why there is no reactive UI that tracks all dependencies and redraws only what needs to be redrawn? (not React, it also re-calculates (but not redraws) everything on every change).
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by codedokode on Sunday November 08, 2026 @12:05AM
(#50410548)
To use memoization you must use immutable structures (otherwise React is unable to detect changes) which are a pain to use and are slow if not designed properly. Do not believe me, try designing for example an algorithm that accepts a huge immutable sorted list with keys, a large sorted list of bulk deletes/inserts and produces a new sorted list with minimum operations. I made 2 or 3 prototypes and they still are not good and not even working properly.
In my book, a good UI framework simply attaches to a mutable model made of arbitrary objects, detect changes and displays it with minimum number of operations. Doesn't require to use any proxies or immutable data or store data in components. Shouldn't be difficult. Why nobody made it, I do not understand.
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by rtpg on Sunday November 08, 2026 @02:40AM
(#50411190)
React isn't immediate mode by my understanding.
In my head it's retained mode + the diffing layer, which sounds the same but if you try to write an "immediate-mode" API (say, using hooks) in React you'll find yourself churning a lot.
At least unless you use the magic React compiler that memo-izes everything correctly.
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by LoganDark on Sunday November 08, 2026 @12:31AM
(#50410677)
> Why there is no reactive UI that tracks all dependencies and redraws only what needs to be redrawn?
Nowadays the focus seems to be on video game-style interfaces that redraw every frame. The justification for this is typically that computers are so fast they can now come up with the entire interface every frame, so why not take advantage of that and forget all this retained-mode complexity?
They don't realize that this is a classic case of the developer's machine fallacy, where the developer has a machine so vastly more powerful than any of their users' that they produce a terrible experience for said users. This is also why games these days typically require upscaling even on 5090, because developers usually have that or something even more powerful and they think the bleeding edge is pushing even THAT machine to its knees.
Developers should be testing their software on the most entry-level, bottom of the barrel Chromebooks from 2015, running the heaviest and most bloated operating system they can think of. If people still optimized their software for that, then maybe computers would still feel almost as fast as the Apple II from 1977.
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by LoganDark on Sunday November 08, 2026 @02:09AM
(#50411085)
That's actually a very good point, I haven't seen any care for power consumption from software developers in many many years. The only people who seem to still care about it are hardware developers like Valve and Apple.
I figure that doing less work generally requires less power, but some developers are crazy and act like they own the whole CPU, generate tons of heat, stress out the cooling system etc. with multithreaded bullshit when they did NOT need to be multithreaded.
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by LoganDark on Sunday November 08, 2026 @04:43AM
(#50411762)
It does indeed depend.
Some multithreaded workloads will use the full logical processor count to pin every core and that can really suck on low-end systems. I think aside from balancing multithreading overhead, this is one of the reasons why some more advanced software (such as 7-Zip) lets you select the number of threads to use for a workload, even if you already know and accept that it'll be expensive until it's completed.
Lots of multithreading things I come across as a developer have a default of something like 4 threads, or only use a certain fraction of logical cores up to a certain maximum, etc. because it's generally more polite not to always pin every core.
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by v1ne on Sunday November 08, 2026 @07:36AM
(#50412729)
Redrawing the whole thing consumes resources. That's power and resources not available to other tasks. There is value in being clever with what you draw.
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by saghm on Sunday November 08, 2026 @09:47AM
(#50413802)
This is an app that connects to your phone and sends messages via the app. I don't think it's that crazy to decide that running on a VM or remote desktop is out of scope.
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by d3Xt3r on Sunday November 08, 2026 @01:58AM
(#50411042)
> Why there is no reactive UI that tracks all dependencies and redraws only what needs to be redrawn?
There's plenty of them. Slint, Floem, iced, Vizia, fltk etc. Slint and fltk in particular also exhibit excellent performance and very little resource usage even without a GPU.
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by loremdifr on Saturday November 07, 2026 @11:59PM
(#50410527)
dont get me wrong, I like the extra performance, but every single alternative whatsapp client has the same issue where it's missing enough core features that you end up needing to go to the browser version often enough to be a nuisance and I end up just using the browser instead (which I hate, I really really would prefer a performant client instead!)
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by mikojan on Sunday November 08, 2026 @07:19AM
(#50412638)
I use this:
$ cat $(which whatsapp)
#!/bin/dash
# A kiosk is full-screen by design. You need to go to about:config and toggle
# full-screen-api.ignore-widgets to true to prevent our window manager from
# creating an actual full-screen window.
# Additionally, you need to set the name to "kiosk" which will set the app id
# under sway to "kiosk" so that in sway you can disable full-screen on
# startup.
firefox --name kiosk -P whatsapp --kiosk https://web.whatsapp.com/
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by sudahtigabulan on Sunday November 08, 2026 @02:04AM
(#50411066)
Sounds reasonable, but IME apps that use relative timestamps switch to absolute time past certain threshold, and then I end up with two adjacent entries "14:38” and "15 minutes ago" and scratching my head.
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by pezezin on Sunday November 08, 2026 @03:18AM
(#50411362)
I hate relative timestamps, I find it much easier to remember specific week days, so I very much prefer this style so I don't have to compute in my head which day of the week I got the text.
Anyway, I tried this application and it seems to mix different styles depending on how long ago you got the text: "yesterday", "Friday", "18 Oct 2026".
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by viraptor on Sunday November 08, 2026 @02:02AM
(#50411053)
That's the annoying thing with WhatsApp, Slack, Discord, etc. Let's say I've got a personal client (that I'm definitely not using...) which works so much better than the official one. I cannot distribute it or use it according to their rules. It's forced enshitification, even though we have better options.
On the good side though - if you're replicating the official behaviour close enough... maybe nobody will know. But then you have to make sure everything, including key sort order, and JA4 of requests matches. And that's tough...
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by d3Xt3r on Sunday November 08, 2026 @02:07AM
(#50411077)
> In our Linux test it opens in under a second and uses about 200 MB of idle RAM
Is it just me or does anyone else feel that 200 MB is a lot for a native chat app written in Rust, that's essentially a remote interface for the WhatsApp on your phone?
I remember back in the day, apps like Miranda IM (and early versions of Trillian) used only digits of RAM, even when you had multiple plugins talking several protocols at the same time, whilst having a ton of advanced features not found in WhatsApp. Yes I get that times have changed and software has become bloated etc, but 200 MB still feels a bit too much.
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by rtpg on Sunday November 08, 2026 @02:36AM
(#50411177)
> Is it just me or does anyone else feel that 200 MB is a lot for a native chat app written in Rust, that's essentially a remote interface for the WhatsApp on your phone?
> I remember back in the day, apps like Miranda IM (and early versions of Trillian) used only digits of RAM, even when you had multiple plugins talking several protocols at the same time
I think what's happening in the second one is that because you're using the native OS toolkits a bunch of stuff is shared, whereas with these "self-contained" "native"-y apps you end up having to load up the whole world and aren't sharing things with everything else
I'd love to be proven wrong but I feel like if you use e.g. Qt you're gonna have to hold onto a bunch of stuff that you wouldn't if you were "just" using OS-native stuff (though maybe that gets shared if you're using the exact same version? Is there something that can be done in this space?)
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by saghm on Sunday November 08, 2026 @09:41AM
(#50413759)
As an additional data point, I recently vibed an egui wrapper around a library I wrote for mod management for a game, and testing it out now, it idles at 92 MB. This implies to me that at least half of the overhead is probably not from the gui framework, but I also don't know how much effort they spent trying to optimize it; I didn't try to optimize my vibed GUI app at all, but I did hand-write the library that it uses for file management, state tracking, etc., and I tend to go out of my way to try to avoid unnecessary allocation in my Rust code. I don't know how much of the memory usage is essentially required overhead or from other dependencies for non-GUI parts of the app, but my instinct is that there's probably a bit of optimization that can be done. I don't think it's crazy for them not to have spent the effort on trying to do that yet though (or potentially even at all, if it's efficient enough for their own personal use).
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by v1ne on Sunday November 08, 2026 @07:33AM
(#50412712)
I just checked with the native WhatsApp client on Windows 11:
650 MB of RAM as it is running, across all its processes. Thus, taking ≈⅓ of RAM is nothing to brag about for a reimplementation that focuses on being lean and fast.
Also, "opens in under a second" – back in the days when SSDs where new, programs opened instantaneously (<60 ms)!
Lastly, I still have to be convinced that Rust is a good choice for GUI programs, considering their messy mutable state and ownership.
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by arjie on Sunday November 08, 2026 @07:30AM
(#50412697)
What purpose would that serve? You have the source code. In the old days we’d just share tarballs. No provenance. It’s fine. You have the unit of legible modifiability.
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by saghm on Sunday November 08, 2026 @09:46AM
(#50413792)
There have definitely been times when I've cloned repos that were vibed, pointed my own agent at it, and then hacked up whatever changes I've wanted. I don't think there's been a single time that a lack of prompts has caused any issues, but there have been at least a few times where stuff like AGENTS.md checked into the repo has caused hiccups from them encoding stuff that conflicts with how I want things done.
Re:ZapFast: A fast, native WhatsApp client in Rust and egui
by Muromec on Sunday November 08, 2026 @07:16AM
(#50412607)
Matrix bridges for sup, signal and the rest are good enough to never use the web client anyway. You can also skip the part where you need to have it installed on the phone by running waydroid (if you can figure out how to scan qr codes with it).
Same for all of these unofficial clients.
I got banned for trying to move my chats from Android to iOS using the app rather than the special tool I didn't know you were supposed to use. I was lucky I eventually got unlocked.
I want a decent WhatsApp client that doesn't crash constantly and where you can search properly, but it's not worth the risk of getting banned again.
0: https://www.whatsapp.com/legal/dma-notice-non-users
but you shouldn't trust these unofficial clients, easy way to get your whatsapp account banned
Egui is definitely not what you want to use on a 4K screen. It is only good for tiny screens of embedded devices.
Why there is no reactive UI that tracks all dependencies and redraws only what needs to be redrawn? (not React, it also re-calculates (but not redraws) everything on every change).
In my book, a good UI framework simply attaches to a mutable model made of arbitrary objects, detect changes and displays it with minimum number of operations. Doesn't require to use any proxies or immutable data or store data in components. Shouldn't be difficult. Why nobody made it, I do not understand.
Use context liberally instead of plumbing things through prop’s needlessly and you’re halfway there.
In my head it's retained mode + the diffing layer, which sounds the same but if you try to write an "immediate-mode" API (say, using hooks) in React you'll find yourself churning a lot.
At least unless you use the magic React compiler that memo-izes everything correctly.
Nowadays the focus seems to be on video game-style interfaces that redraw every frame. The justification for this is typically that computers are so fast they can now come up with the entire interface every frame, so why not take advantage of that and forget all this retained-mode complexity?
They don't realize that this is a classic case of the developer's machine fallacy, where the developer has a machine so vastly more powerful than any of their users' that they produce a terrible experience for said users. This is also why games these days typically require upscaling even on 5090, because developers usually have that or something even more powerful and they think the bleeding edge is pushing even THAT machine to its knees.
Developers should be testing their software on the most entry-level, bottom of the barrel Chromebooks from 2015, running the heaviest and most bloated operating system they can think of. If people still optimized their software for that, then maybe computers would still feel almost as fast as the Apple II from 1977.
https://danluu.com/input-lag/
I figure that doing less work generally requires less power, but some developers are crazy and act like they own the whole CPU, generate tons of heat, stress out the cooling system etc. with multithreaded bullshit when they did NOT need to be multithreaded.
Some multithreaded workloads will use the full logical processor count to pin every core and that can really suck on low-end systems. I think aside from balancing multithreading overhead, this is one of the reasons why some more advanced software (such as 7-Zip) lets you select the number of threads to use for a workload, even if you already know and accept that it'll be expensive until it's completed.
Lots of multithreading things I come across as a developer have a default of something like 4 threads, or only use a certain fraction of logical cores up to a certain maximum, etc. because it's generally more polite not to always pin every core.
Basically every device has a GPU.
Why is it bad on 4K?
Did you measure anything in a real setup?
it's an incredible waste of resources, especially at high resolutions, to redraw a Gui application like you would a videogame
Many VMs and remote desktops don't. (Or can't really make use of)
There's plenty of them. Slint, Floem, iced, Vizia, fltk etc. Slint and fltk in particular also exhibit excellent performance and very little resource usage even without a GPU.
Signal does that and I hate it when it happens.
- Screenshots don't age well: you need to know the screenshot time and do math
- They need to be maintained, which means the screen keeps updating even if nothing else is happening
It is silly to mix the two. I usually display the relative time and offer a timestamp on hover or if there's space, show both.
Anyway, I tried this application and it seems to mix different styles depending on how long ago you got the text: "yesterday", "Friday", "18 Oct 2026".
On the good side though - if you're replicating the official behaviour close enough... maybe nobody will know. But then you have to make sure everything, including key sort order, and JA4 of requests matches. And that's tough...
Is it just me or does anyone else feel that 200 MB is a lot for a native chat app written in Rust, that's essentially a remote interface for the WhatsApp on your phone?
I remember back in the day, apps like Miranda IM (and early versions of Trillian) used only digits of RAM, even when you had multiple plugins talking several protocols at the same time, whilst having a ton of advanced features not found in WhatsApp. Yes I get that times have changed and software has become bloated etc, but 200 MB still feels a bit too much.
> I remember back in the day, apps like Miranda IM (and early versions of Trillian) used only digits of RAM, even when you had multiple plugins talking several protocols at the same time
I think what's happening in the second one is that because you're using the native OS toolkits a bunch of stuff is shared, whereas with these "self-contained" "native"-y apps you end up having to load up the whole world and aren't sharing things with everything else
I'd love to be proven wrong but I feel like if you use e.g. Qt you're gonna have to hold onto a bunch of stuff that you wouldn't if you were "just" using OS-native stuff (though maybe that gets shared if you're using the exact same version? Is there something that can be done in this space?)
That was my first thought. But considering it as a significant improvement from > 1 GB, I guess it is what it is.
> I remember back in the day, apps like Miranda IM (and early versions of Trillian) used only digits of RAM ...
Sadly this was true for many apps.
Turns out all those zero cost abstractions add up to a lot!
Is there actually a way to see a breakdown of memory usage for a program? If you want to see where all the memory is going?
Flame graphs are a pretty common tool for this (maybe slightly less common than using them for seeing the breakdown of the time spent when running).
Lastly, I still have to be convinced that Rust is a good choice for GUI programs, considering their messy mutable state and ownership.
In the early days of AI coding someone did publish the prompts and it was utterly useless to me https://github.com/i365dev/LetterDrop
The source code itself is a sufficient prompt.