Almost every browser we use daily relies on one of three rendering engines: Google's Blink, Apple's WebKit or Mozilla's Gecko. OpenHeronBrowser (OHB) takes a different route: it is a browser for macOS, Windows and Linux built on an engine of its own, written from scratch in Rust and compact enough for a single developer to study in full. Version 1.0.0 is a downloadable demo, and the project presents itself as an attempt to build an open browser independent from the large companies of the sector.
The engine and the browser around it amount to about 85,000 lines of Rust, plus about 23,000 lines of JavaScript that implement the DOM and web APIs. The JavaScript layer runs on Boa, an interpreter also written in Rust, with patches for speed and correctness included in the project. For WebAssembly, the format that lets compiled code run in the browser, OHB uses wasmi. The project page also declares an Apache 2.0 license, a detail not yet verified by other sources.
The standard test results are the most concrete point. Sul versante opposto, NeoBrowser pilota il vero Chrome con le sessioni autentiche dell'utente, con un binario Rust da 4 MB, nel tentativo di superare i bot check. On Acid3, the historic test of web standards compliance, OHB scores 97 out of 100, the same as current Chromium. The three subtests it fails check behaviour that the DOM specification changed in 2011, and every other browser fails them too. It does pass Acid2, the smiley-face test. On html5test.com the project reaches 483 out of 555, with every HTML parsing rule passing: Firefox scores 509 and Chrome 523. On the web-platform-tests, the official suite, the DOM, events, selectors and forms sections pass 66,596 of 69,049 subtests, roughly 96%.
In practice most sites open correctly. Logins to Microsoft, GitHub and Hugging Face work, and reCAPTCHA challenges pass. Discord opens and signs in, VS Code for the Web responds, and the v86 emulator boots Windows 1.01 with Notepad. Games such as lichess and Super Mario Bros. run, while YouTube lets you browse but not yet play videos. The weak point remains speed: script-heavy sites are slower than in Chrome, because the interpreter runs code rather than compiling it.
The project arrives as AI changes how software is written, and its code was developed with the help of Claude. Anyone who has worked on rendering engines knows how hard it is to keep up with standards, and an independent browser is a technical bet more than a commercial one. For now OHB is a preview: some sites do not work, pages are not sandboxed as in mature browsers, and the project advises against entering passwords or sensitive data. The developers say the demo will evolve into the main engine of the project.
Image: Heronetic — https://github.com/Heronetic/OpenHeronBrowser
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