Show HN: Firefox in WebAssembly

ccoolelectronics about 3 hours ago 48 commentsRead Article on developer.puter.com

DE version is available. Content is displayed in original English for accuracy.

This is the entire Firefox browser rendering to a <canvas> element. Gecko, all UI components, and the Spidermonkey JS engine are all compiled and running in WebAssembly.

Here are a few things you might find interesting:

- This is fully end to end encrypted! We use the WISP protocol for TCP-over-websockets.

- There is a novel WASM->JS JIT for experimental site speedup

- This port cost over 25k in opus/fable tokens for debugging and JIT research

This was just a fun experiment to push the boundaries of WebAssembly. For a more usable "browser in browser" experience, we also built https://github.com/HeyPuter/browser.js that eats a bit less RAM.

⚡ Community Insights

Discussion Sentiment

81% Positive

Analyzed from 1384 words in the discussion.

Discussion (48 Comments)Read Original on HackerNews

elmer2•4 minutes ago

I would be careful with this demo. When you go to whatismyip.com, it's showing: 104.28.233.73. Someone could use this to cloak their IP address and do some damage.

koolala•4 minutes ago

What makes it require that WASM extension you need the flag for in Firefox? Was there really no way to work around it or polyfill it for it to work? It is performance critical?

rlmineing_dead•2 minutes ago

JSPI is used for wasmfs's OPFS backend iirc but also yes it's very annoying to work around and the alternative is asyncifify which bloats the binary like 200% and has 50% slower runtime speeds

yjftsjthsd-h•about 1 hour ago

>This port cost over 25k in opus/fable tokens for debugging and JIT research

> This was just a fun experiment to push the boundaries of WebAssembly

I'm a huge fan of the project, but I have to ask. If spending $25k is a "fun experiment", where exactly is your threshold for serious work?

tiagod•about 1 hour ago

Was it really $25k, or was it done though subscriptions with a reported cost of $25k?

I'm on the openai $100 sub and frequently my codexbar will show $250 usage in a day. I think it probably doesn't have access to the cached token share too, which probably inflates that a lot.

smalltorch•about 1 hour ago

I imagine it is 25k tokens not dollars

yjftsjthsd-h•33 minutes ago

https://news.ycombinator.com/item?id=48927724 seems to say dollars? Although yes the phrasing could be clearer in the post

dangoodmanUT•29 minutes ago

25k tokens is a few turns

rustyhancock•about 1 hour ago

That's standard token usage for /init

degamad•about 2 hours ago

I'm so glad this exists, I've been considering doing something like this for a few months.

I recently got a TV based on VIDAA os, a locked-down linux-based OS where everything is rendered from Web pages. It has a built-in browser that doesn't support ad-blocking (I suspect VIDAA is profiting from showing ads on the TV), and you can't install new apps unless they're Web pages.

This would hopefully allow one to run Firefox within the existing browser, then install uBlock Origin within Firefox... I know what this weekend's project is going to be...

coolelectronics•about 2 hours ago

We also plan on adding extension support to https://github.com/HeyPuter/browser.js soon, which should hopefully cover use cases like that as well without the full overhead

shevy-java•about 1 hour ago

Firefox should really bundle ublock origin as-is. I install it afterwards anyway but I don't understand Mozilla here. They seem to want to stay behind Google.

quantummagic•about 1 hour ago

In 2024, "search royalties" brought in approximately $585 million for Mozilla, largely from Google. It's not hard to see why they tread very lightly around ad blocking. It's actually impressive that ublock remains easy and painless to install as an extension.

coolelectronics•about 2 hours ago

Oh and for anyone asking, you can run firefox-wasm inside firefox-wasm inside firefox! I only got this to load once though since it gets pretty unstable at that level.

brewmarche•about 1 hour ago

Can’t get it running on Firefox 152.0.6 (aarch64), no extensions.

  [chrome-demo] chrome assets ready
  [gecko] warning: unsupported syscall: __syscall_madvise
  [gecko] embed-xul: main() on the app pthread (PROXY_TO_PTHREAD)
  [gecko] embed-xul: GECKO_GL_PASSTHROUGH=1
  [gecko] embed-xul: GECKO_COARSE_CLOCK=1
  [gecko] embed-xul: GECKO_GPU=1 (GPU/WebRender->canvas rendering)
  [gecko] xul_init: GRE dir = /gre
  [gecko] Pthread 0x11051000 sent an error! blob:https://developer.puter.com/edc1bd0a-b844-4a18-a69a-63dd49dc304a:8906: SecurityError: Security error when calling GetDirectory

rlmineing_dead•about 1 hour ago

Running firefox on aarch64 here right now (Ubuntu 26.04 ARM on snapdragon X1E)

did you enable the about:config option? it may be required

brewmarche•about 1 hour ago

Yes, you don’t get that far without it.

rlmineing_dead•less than a minute ago

What's your GPU driver? There's a good chance this is a bug with the GPU passthrough. You can fall back to software rendering in the advanced options while it's starting if you want to try

MajesticHobo2•about 2 hours ago

Browser sandboxing is now fully solved.

yjftsjthsd-h•about 1 hour ago

In mean... It kinda feels like this is legitimately true? An attacker trying to do anything on a user's machine through this would have to find a Firefox vulnerability and a vulnerability in the wasm runtime, which is such a high bar that I would actually feel remarkably safe running this thing. The only question is how performance works and whether there are any pain points using as a daily driver, but those feel likely to be a pretty minor point. Oh, and the usual caveat that an attacker can still compromise things inside the sandbox which does leave a certain amount of exposure (but if you run different things in different instances they're isolated).

rlmineing_dead•42 minutes ago

This is true but also this is probably also only half true. Sandboxing is not a fully solved issue since this 100% degrades firefox sandboxing since fission cant run and its running in singleprocess mode. Just wanted to be honest about this

azakai•about 2 hours ago

Prior art: WebKit.js, the WebKit rendering engine ported to JS

https://github.com/trevorlinton/webkit.js/

SpyCoder77•14 minutes ago

No mobile support

zerof1l•about 1 hour ago

All the network traffic from that browser is routed through a server. My IP inside that browser was in India and on CloudFlare network. I don’t particularly trust Puter. Why not route traffic through my actual browser?

koolala•8 minutes ago

>Why not route traffic through my actual browser?

Because you can't. Not even an Extension is able to. Browsers don't want you to bypass their content enforcement. I wish we had at least one hacker friendly browser.

kevincox•about 1 hour ago

Because the web browser can't make arbitrary network connections. Even if it was implemented intercepting at the HTTP layer (which would probably be much more difficult than just intercepting the low level socket operations) you wouldn't be able to properly manage CORS headers, cookies and various other things.

rlmineing_dead•about 1 hour ago

The TCP proxy exit node we're using is running on Cloudflare, you can check that your traffic is still TLS encrypted by OpenSSL (also compiled to webassembly). The browser does not have a native API to send raw TCP so the proxying is done by the http://github.com/MercuryWorkshop/wisp-protocol protocol. You can check your packets in dev tools, look for a socket connection with "puter.cafe" as the host for our TCP proxy. This application is meant to be a demo for it actually (why it says at the bottom that its powered by puter networking). That is the only server side component of this.

Retr0id•about 1 hour ago

I was reading your landing page at https://developer.puter.com/networking/ and was very confused by how you were achieving the "with no server or proxy" part, until much further down the page:

> "the connection is tunneled over a single WebSocket to a Puter relay"

Come on, it's both a server and a proxy, and it doesn't stop being those things just because you're calling it a relay.

ent101•about 1 hour ago

I wrote that and I think you're right. We were trying to convey that you don't need to set up anything, but the wording could definitely be better. I'll change it.

rlmineing_dead•about 1 hour ago

apologies yes there is a wording error here, the correct wording is no CORS proxy, the reason why this is important is because cors proxies are inherently insecure (this is different because the TLS is done in your browser with a webassembly library).

no servers is referring to you not needing to host servers in the same as the term "serverless". Such is the ways of modern tech terms I fear

ent101•about 1 hour ago

Puter's networking is open-source and e2e encrypted. Also, a regular browser doesn't give access to raw TCP sockets used for this, so it wouldn't be possible to route through your browser.

gnabgib•about 1 hour ago

So it's just the three accounts you have now? (Show by @coolelectronics now and 7 months ago [1], show from you/@ent101 2d ago [0], 2025[2,3,4], 2024[5,6,7,8,9,A,B,C,D], 2023[E], @george0812 2022[F])

[0]: https://news.ycombinator.com/item?id=48895945

[1]: https://news.ycombinator.com/user?id=coolelectronics

[2]: https://news.ycombinator.com/item?id=45522061

[3]: https://news.ycombinator.com/item?id=44193514

[4]: https://news.ycombinator.com/item?id=42675696

[5]: https://news.ycombinator.com/item?id=41849494

[6]: https://news.ycombinator.com/item?id=41682779

[7]: https://news.ycombinator.com/item?id=41360683

[8]: https://news.ycombinator.com/item?id=41040761

[9]: https://news.ycombinator.com/item?id=40802253

[A]: https://news.ycombinator.com/item?id=39829463

[B]: https://news.ycombinator.com/item?id=39672886

[C]: https://news.ycombinator.com/item?id=39597030

[D]: https://news.ycombinator.com/item?id=39036897

[E]: https://news.ycombinator.com/item?id=38202220

[F]: https://news.ycombinator.com/item?id=31611016

ent101•20 minutes ago

what do you mean? we're a team of 10 and have 390 contributors. We post regularly, including me.

simonw•about 1 hour ago

This is amazing. I loaded up https://developer.puter.com/labs/firefox-wasm/ in Chrome and I've visited a bunch of sites, it works really well.

Then I opened up https://developer.puter.com/labs/firefox-wasm/ in Firefox-in-WebAssembly-in-Chrome

... and sadly it didn't load. I got this in the startup log:

  [log] [chrome-demo] chrome assets ready
  [warn] [gecko] warning: unsupported syscall: __syscall_madvise

sangeeth96•about 2 hours ago

edit: I misunderstood, that's $25k not 25k tokens :/ time to log off.

this is so rad! 25k tokens is a lot less than i thought this'd take -- what were the difficult bits in the porting process? also, was firefox preferred because parts of it are already in rust?

coolelectronics•about 2 hours ago

$25k of tokens, closer to 30 billion I believe. It only took a few days to actually get the engine up, the hard parts where most of the effort was spent was squeezing out performance and increasing stability, as well as attempting the JIT.

Firefox was chosen because its single-process support was in a better place than chromium/blink. WebKit is also possible, it was done by a friend of mine earlier https://github.com/theogbob/WebkitWasm

sangeeth96•about 2 hours ago

ah, i misunderstood. that seemed way too low in terms of actual tokens lol. i'll log off now. interesting details and didn't know about WebkitWasm. hope to read more soon.

eqrion•about 2 hours ago

> There is a novel WASM->JS JIT for experimental site speedup

I would love to see the details for this. SpiderMonkey had an attempted wasm32 JIT backend, but it was never finished.

edit: Apparently it also has some sort of WebAssembly interpreter backend too, which SpiderMonkey doesn't have.

throwaway2027•about 2 hours ago

Obligatory https://www.destroyallsoftware.com/talks/the-birth-and-death...

rlmineing_dead•about 2 hours ago

I had this in mind when I first saw this project too LOL

Every year I need to rewatch this talk

mdlxxv•about 2 hours ago

"Yo dawg. I herd you like web browsers, so I put a browser in your browser, so you can browse the Web while you browse the Web".

ent101•about 2 hours ago

should've used this in the splash screen :(

som•about 2 hours ago

... doesn't support Firefox mobile apparently :D

rlmineing_dead•about 2 hours ago

Does firefox mobile (Android, since firefox mobile iOS is a WebKit wrapper) support about:config settings? if so you can enable wasm_js_promise_integration in about:config and have it working likely. I will test this on my Pixel 10 pro

rlmineing_dead•about 2 hours ago

hi reporting back, yes stock firefox mobile wont work but the BETA version will because it just added the WASM feature needed (firefox 153 adds it but regular mobile firefox lacks about:config support it seems)

and by "will work" I mean will render the first frame and then freeze

YMMV

jedisct1•about 1 hour ago

"This browser doesn't support WebAssembly JSPI, which Firefox WASM needs to run."

rlmineing_dead•40 minutes ago

safari? I think its going to be added in 27