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Show HN: Lightpanda, an open-source headless browser in Zig

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Show HN: Lightpanda, an open-source headless browser in Zig

#1

Post by fbouvier »

We’re Francis and Pierre, and we're excited to share Lightpanda (https://lightpanda.io), an open-source headless browser we’ve been building for the past 2 years from scratch in Zig (not dependent on Chromium or Firefox). It’s a faster and lighter alternative for headless operations without any graphical rendering.

Why start over? We’ve worked a lot with Chrome headless at our previous company, scraping millions of web pages per day. While it’s powerful, it’s also heavy on CPU and memory usage. For scraping at scale, building AI agents, or automating websites, the overheads are high. So we asked ourselves: what if we built a browser that only did what’s absolutely necessary for headless automation?

Our browser is made of the following main components:

- an HTTP loader

- an HTML parser and DOM tree (based on Netsurf libs)

- a Javascript runtime (v8)

- partial web APIs support (currently DOM and XHR/Fetch)

- and a CDP (Chrome Debug Protocol) server to allow plug & play connection with existing scripts (Puppeteer, Playwright, etc).

The main idea is to avoid any graphical rendering and just work with data manipulation, which in our experience covers a wide range of headless use cases (excluding some, like screenshot generation).

In our current test case Lightpanda is roughly 10x faster than Chrome headless while using 10x less memory.

It's a work in progress, there are hundreds of Web APIs, and for now we just support some of them. It's a beta version, so expect most websites to fail or crash. The plan is to increase coverage over time.

We chose Zig for its seamless integration with C libs and its comptime feature that allow us to generate bi-directional Native to JS APIs (see our zig-js-runtime lib https://github.com/lightpanda-io/zig-js-runtime). And of course for its performance :)

As a company, our business model is based on a Managed Cloud, browser as a service. Currently, this is primarily powered by Chrome, but as we integrate more web APIs it will gradually transition to Lightpanda.

We would love to hear your thoughts and feedback. Where should we focus our efforts next to support your use cases?

Show HN: Lightpanda, an open-source headless browser in Zig
github.com

Re: Show HN: Lightpanda, an open-source headless browser in Zig

#2

Post by fbouvier »

Author here. The browser is made from scratch (not based on Chromium/Webkit), in Zig, using v8 as a JS engine.

Our idea is to build a lightweight browser optimized for AI use cases like LLM training and agent workflows. And more generally any type of web automation.

It's a work in progress, there are hundreds of Web APIs, and for now we just support some of them (DOM, XHR, Fetch). So expect most websites to fail or crash. The plan is to increase coverage over time.

Happy to answer any questions.

Re: Show HN: Lightpanda, an open-source headless browser in Zig

#5

Post by toobulkeh »

fbouvier wrote: post #2

Author here. The browser is made from scratch (not based on Chromium/Webkit), in Zig, using v8 as a JS engine. Our idea is to build a lightweight browser optimized for AI use cases like LLM training and agent workflows. And more generally any type of web automation. It's a work in progress, there are hundreds of Web APIs, and for now we just support some of them (DOM, XHR, Fetch). So expect most websites to fail or c…

I’d love to see better optimized web socket support and “save” features that cache LLM queries to optimize fallback

Re: Show HN: Lightpanda, an open-source headless browser in Zig

#6

Post by katiehallett »

m3kw9 wrote: post #4

How does this work because the browser needs to render a page and the vision model needs to know where a button is, so it still needs to see an image. How does headless make it easier?

Headless mode skips the visual rendering meant for humans, but the DOM structure and layout still exist, allowing the model to parse elements programmatically (e.g. button locations). Instead of 'seeing' an image, the model interacts with the page's underlying structure, which is faster and more efficient. Our browser removes the rendering engine as well, so it won't handle 100% of automation use cases, but it's also what allows us to be faster and lighter than Chrome in headless mode.

Re: Show HN: Lightpanda, an open-source headless browser in Zig

#7

Post by JoelEinbinder »

fbouvier wrote: post #2

Author here. The browser is made from scratch (not based on Chromium/Webkit), in Zig, using v8 as a JS engine. Our idea is to build a lightweight browser optimized for AI use cases like LLM training and agent workflows. And more generally any type of web automation. It's a work in progress, there are hundreds of Web APIs, and for now we just support some of them (DOM, XHR, Fetch). So expect most websites to fail or c…

When I've talked to people running this kind of ai scraping/agent workflow, the costs of the AI parts dwarf that of the web browser parts. This causes computational cost of the browser to become irrelevant. I'm curious what situation you got yourself in where optimizing the browser results in meaningful savings. I'd also like to be in that place!

I think your ram usage benchmark is deceptive. I'd expect a minimal browser to have much lower peak memory usage than chrome on a minimal website. But it should even out or get worse as the websites get richer. The nature of web scraping is that the worst sites take up the vast majority of your cpu cycles. I don't think lowering the ram usage of the browser process will have much real world impact.

Re: Show HN: Lightpanda, an open-source headless browser in Zig

#8

Post by dtj1123 »

fbouvier wrote: post #2

Author here. The browser is made from scratch (not based on Chromium/Webkit), in Zig, using v8 as a JS engine. Our idea is to build a lightweight browser optimized for AI use cases like LLM training and agent workflows. And more generally any type of web automation. It's a work in progress, there are hundreds of Web APIs, and for now we just support some of them (DOM, XHR, Fetch). So expect most websites to fail or c…

Very nice. Does this / will this support the puppeteer-extra stealth plugin?

Re: Show HN: Lightpanda, an open-source headless browser in Zig

#9

Post by sesm »

fbouvier wrote: post #2

Author here. The browser is made from scratch (not based on Chromium/Webkit), in Zig, using v8 as a JS engine. Our idea is to build a lightweight browser optimized for AI use cases like LLM training and agent workflows. And more generally any type of web automation. It's a work in progress, there are hundreds of Web APIs, and for now we just support some of them (DOM, XHR, Fetch). So expect most websites to fail or c…

Great job! And good luck on your journey!

One question: which JS engines did you consider and why you chose V8 in the end?

Re: Show HN: Lightpanda, an open-source headless browser in Zig

#10

Post by weinzierl »

If I don't need JavaScript or any interactivity, just modern HTML + modern CSS, is there any modern lightweight renderer to png or svg?

Something in the spirit of wkhtmltoimage or WeasyPrint that does not require a full blown browser but more modern with support of recent HTML and CSS?

In a sense this is Lightpanda's complement to a "full panda". Just the fully rendered DOM to pixels.

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