Northstar Web Browser

Northstar Web Browser is a minimalist web browser written from scratch in C. Its engine targets practical HTML5, modern CSS and JavaScript compatibility without embedding Gecko, WebKit, Blink or another browser engine. Linux is the primary platform; macOS and Windows are also supported.

Repository: https://github.com/nordstjernen-web/northstar-web-browser.
Windows store: https://apps.microsoft.com/detail/9p39zb79jv0t

See Nordstjernen Sol also, which is the most complete, fully featured web browser project we are making. Nordstjernen Sol has ready-made builds for Windows, macOS, Linux and Android.

Northstar Web Browser is licensed under the GNU General Public License, version 3 or later.

Multiple browser variants

• This repo, Northstar Web Browser, is a minimalist, simple and good web browser: one process, one page per window, GPL only. It is more about research into browser technology.
• Nordstjernen Sol is the Nordstjernen web browser, the most complete, fully featured web browser, with tabs in sandboxed renderer processes and builds for desktop and Android.
• Southstar is Nordstjernen Sol rewritten in Rust, with the Boa JavaScript engine.

We are doing web browser innovation, research and development, and part of this is making multiple web browser variants to test and compare.

Web standards: Behaviour is measured against the specification text, section by section, not against another browser. The engine runs web-platform-tests through headless mode; see docs/compliance.md for the current per-area scores and the known structural gaps.

Security: on Linux the browser runs behind a Landlock filesystem sandbox (plus PR_SET_NO_NEW_PRIVS) and a default-deny seccomp syscall filter, which also refuses executable memory, new namespaces and signals to other processes, in both GUI and headless/tooling modes. On macOS a sandbox profile confines writes, and on Windows the process runs with mitigation policies. There is no JIT. Frames, workers and extensions are held to their own origin and Content-Security-Policy. See SECURITY.md for the exact per-mode posture and the known gaps.

Minimalism: one page per window, one process. The GTK shell runs on the main thread and the page engine on one dedicated thread with its own main loop, so a slow page never freezes the window; the shell posts requests to that thread and gets rendered frames back, all inside the same process. The engine is a compact body of C — about 207,000 lines of original C, excluding the vendored web-text-lib, WAMR, Wuffs and audio decoders — small enough for one person to read and audit end-to-end. See docs/architecture.md for how it fits together.

What this edition is

This edition strips Nordstjernen down to a tab-less, single-process desktop browser, based on the Nordstjernen project. It deliberately omits tabs, per-tab renderer processes, WebGL, WebGPU, an embedded PDF viewer and AI-style web APIs. It does not send telemetry or update pings.

Audio and video still play in-process (MP3, MP2, AAC, Ogg Opus/Vorbis; MPEG-1, and AV1, VP9 and H.264 when their decoders are present). Images decode in-tree (PNG/APNG, GIF, BMP, JPEG and WebP via Wuffs, AVIF through libavif when available, and SVG in the engine).

No AI policy

From October 2026, Northstar Web Browser is developed without AI. Contributions — code, documentation, translations, issues and pull requests — must be written by people, not generated by AI coding assistants, large language models or similar tools. Pull requests that contain AI-generated content will not be accepted. The repository carries no AI-assistant configuration (such as CLAUDE.md, AGENTS.md, .claude/ or .agents/), and none should be added.

Browser features

• HTML parsed to a DOM by lexbor; CSS by the engine's own cascade — flex, grid and subgrid, transforms, gradients, @keyframes, scroll snap, container queries, cascade layers, :has(), nesting, @property, and typed calc() math over lengths, angles, times and resolutions.
• JavaScript on the quickjs-ng interpreter (or Fabrice Bellard's original QuickJS) — DOM, Shadow DOM, Mutation/Intersection/Resize/ Performance observers, Intl, Canvas 2D (Path2D, ImageBitmap, DOMMatrix, OffscreenCanvas), WebCrypto (crypto.subtle over OpenSSL).
• Custom elements — autonomous and customized built-in elements.
• Workers — dedicated workers with structured-clone messaging, message channels and broadcast channels.
• Storage — IndexedDB over SQLite, localStorage/sessionStorage and the Cache API (caches, request/response pairs per the Service Workers specification, kept in IndexedDB), each partitioned by origin.
• Live connections — WebSockets (with libcurl 8.11 or newer, or one built with WebSocket support) and server-sent events.
• Navigation API — window.navigation for single-page routing.
• Service workers — origin-scoped registration, persistence, controlled-page fetch interception and offline pages served from the Cache API.
• WebExtensions — installed local extensions with manifest content scripts, storage.local kept apart per extension, i18n, declarativeNetRequest rule sets, and packaged resources that pages can load only when the extension lists them in web_accessible_resources.
• Networking over HTTP/2 with libcurl — HTTP/3 through Alt-Svc when the linked libcurl provides it — HTTPS-first navigation, HSTS, optional DNS-over-HTTPS, CSP, subresource-integrity (SRI) checks for scripts, and cookies partitioned by site — one libcurl cookie store per site, shared by document.cookie and that site's network requests.
• Safe browsing — before a top-level navigation is fetched, its host is checked against a local SHA-256 blocklist. The check runs entirely on-device. The bundled list carries only test entries; a real list goes in ~/.config/northstar/safebrowsing.list or is named by NS_SAFEBROWSING_LIST.
• Media — images (PNG/APNG, GIF, BMP, JPEG, WebP, optional AVIF, SVG); audio () decodes and plays in the browser process, alongside a Web Audio graph. plays MPEG-1 () decoded in-tree by the same pl_mpeg that already handles MP2 audio, a program stream's MP2 track included, with no extra dependency or licence. Streaming sites play through Media Source Extensions: and demux fragmented MP4 and WebM, a decoder thread per video decodes AV1 (libdav1d), VP9 (libvpx) or H.264 (OpenH264) a few frames ahead, and the sound decodes AAC-LC (in-tree) or Opus (libopus). A plain MP4 or WebM file in is fetched progressively with HTTP range requests and plays through the same path. Decoded pictures are kept only a few frames ahead of the playhead, and draws a play/pause button, seek bar, time and mute button.

Install with npm

sudo npm install -g northstar-browser
northstar https://nordstjernen.org

On Linux, macOS and the BSDs, run the install with sudo, because npm's global directory belongs to root; on Windows, run it without sudo.

The package builds Northstar from the release source on Linux, macOS, the BSDs and Windows (with MSYS2), and first names any build dependency that is missing. See npm/README.md.

Build and run

On Debian or Ubuntu, install the required development packages:

sudo apt install build-essential git pkg-config meson ninja-build cmake \
    libgtk-4-dev libcurl4-openssl-dev libssl-dev libuchardet-dev \
    libharfbuzz-dev libfribidi-dev libcairo2-dev libfontconfig-dev \
    libfreetype-dev libpsl-dev libsqlite3-dev libseccomp-dev libsdl2-dev \
    zlib1g-dev
meson setup builddir
meson compile -C builddir
./builddir/src/gtk/northstar

For macOS (Homebrew or MacPorts), other Linux distributions and Windows, see docs/building.md. To build, run and debug from Visual Studio Code, see docs/vscode.md.

The development helper configures the default build directory when needed and runs the same compile command:

./scripts/dev.sh build
./scripts/dev.sh smoke

The smoke command renders deterministic local fixtures through the headless engine and compares them with the checked-in baselines. A single page can also be rendered directly:

./builddir/src/gtk/northstar --headless --dump=text about:start

Meson feature options include -Davif=disabled, -Daudio=disabled, -Dwasm=disabled, -Dav1=disabled, -Dvp9=disabled and -Dh264=disabled for smaller builds; only Cisco's prebuilt OpenH264 binaries carry Cisco's H.264 patent licence, so -Dh264=disabled drops it where that matters. -Djs_engine=quickjs builds on Fabrice Bellard's original QuickJS instead of the default quickjs-ng.

WAMR, Wuffs, pl_mpeg, minimp3 and web-text-lib are vendored in-tree. lexbor and quickjs-ng are pinned upstream subprojects (see subprojects/*.wrap) that meson setup fetches; see docs/building.md for how a pin is moved.

The open-internet-browser command

meson install puts open-internet-browser beside northstar in the binary directory, a symbolic link to it, so open-internet-browser https://nordstjernen.org starts Northstar Web Browser. Nordstjernen Sol and Southstar install commands of their own (open-browser-nordstjernen and internet-browser-southstar), so the three browsers install side by side. The .deb and .rpm packages register open-internet-browser with update-alternatives instead of shipping the link. On Windows the installer registers open-internet-browser as an App Paths alias (the Run dialog and start open-internet-browser find it) and the MSIX package declares it as an app execution alias.

Dependencies

Northstar Web Browser's engine is written from scratch — it contains no forked browser engine (no Gecko, WebKit, or Blink). It is the GPL edition of the Nordstjernen project.

Pinned upstream meson subprojects (subprojects/*.wrap), fetched by meson setup:

Component	Role
lexbor v3.0.1 (commit 7e278c0)	HTML5 → DOM parser and the WHATWG URL module
quickjs-ng 0.17.0+ (master 9b06171)	JavaScript engine — no JIT
QuickJS 2026-06-04	The original JavaScript engine, used instead of quickjs-ng with -Djs_engine=quickjs

lexbor (3.0 or newer) and quickjs-ng take a system copy instead when the build finds one.

Vendored in-tree (built from the main tree, no submodules):

Component	Role
WAMR 2.4.5 (subset)	WebAssembly fast interpreter
Wuffs v0.4	Memory-safe image decoding — PNG/APNG, GIF, BMP, JPEG, WebP
pl_mpeg (MIT)	In-process MPEG-1 video and MP2 audio decode
minimp3 (CC0)	In-process MP3 audio decode
web-text-lib (src/web-text-lib/, LGPL 2.1+)	Text itemization, shaping and line breaking — Nordstjernen's Pango fork with a cross-layout shaping cache, shared with Nordstjernen Sol

Required system libraries: GTK 4 (≥ 4.14; ≥ 4.22.1 on Windows), GLib (≥ 2.80), Cairo (≥ 1.18), HarfBuzz (≥ 8.3), FriBidi (≥ 1.0.6), fontconfig (≥ 2.15), FreeType, libcurl (≥ 8.5), OpenSSL (libcrypto), uchardet, libpsl, SQLite and zlib — Ubuntu 24.04, Debian 13 and Fedora 40 meet every floor; Ubuntu 22.04 and older cannot build it. The engine lays text out through web-text-lib rather than the system Pango; GTK still links the system Pango for its own widgets, and the two coexist because every symbol in the fork is renamed. Linux builds also require libseccomp. SDL2 provides audio output: it is picked up when present and required with -Daudio=enabled.

Optional (auto-detected): libdav1d, libvpx and OpenH264 (AV1, VP9 and H.264 video), libopus (Opus audio in WebM and MP4), libavif (AVIF images), opusfile / vorbisfile (in-process Ogg audio), Enchant (spell-checking) and libthai (Thai line breaking).

License

Northstar Web Browser is free software, licensed under the GNU General Public License, version 3 or later — see LICENSE.

Project home: https://nordstjernen.org/northstar-browser/ · Copyright 2026 Andreas Røsdal.

Builds