T.A.B.

Coming soon

T.A.B. Tiny Ass Browser

A web browser engine built from scratch in Rust. Every layer ours.

Our own JavaScript engine, HTML and CSS parsing, layout, rasterizer, fonts, image decoders and WebAssembly — no borrowed engine underneath.

See the conformance board Watch on GitHub

Launching at gettab.dev

92.63% of 1,912,797 conformance test cases pass on the latest full run

Latest full conformance run

1,771,791 test cases passing.

Every number below is the full upstream catalog. Nothing filtered, nothing hand-picked.

  • Engine Kingmaker 0.1.2680
  • Run 20261026T181030Z-3c822369cbad
  • Finished
92.63% overall

1,771,791 of 1,912,797 test cases

Five suites, one run, one engine build.

  1. Test262

    97.85%

    ECMAScript language & built-ins

    95,931 / 98,040

  2. WPT testharness

    91.91%

    Web Platform Tests — scripted API tests

    1,457,276 / 1,585,538

  3. WPT rendering

    88.93%

    Web Platform Tests — reftests, pixel-compared

    27,470 / 30,888

  4. WPT remaining

    87.91%

    Web Platform Tests — remaining compatibility catalog

    52,493 / 59,710

  5. WebAssembly

    100.00%

    Official WebAssembly spec test suite

    138,621 / 138,621

Full upstream catalogs

Denominators are the complete Test262, Web Platform Tests and WebAssembly spec catalogs. No skip list, no curated subset.

Scored per test case

Subtests count individually — a WPT file with 40 subtests is 40 rows, and each Test262 file is scored in strict and sloppy mode where it applies.

Only a pass is a pass

Failures, timeouts, harness errors, skipped and not-run cases all stay in the denominator and count against the score.

What's inside

The whole stack, in Rust.

Written from scratch, layer by layer — from the bytes off the wire to the pixels on screen.

  • km-js

    JavaScript engine

    Parser, bytecode VM, garbage collector and the built-in library.

  • km-dom

    HTML & DOM

    Spec-shaped HTML parsing into an owned document tree.

  • km-css

    CSS

    Parsing, selector matching and the cascade.

  • km-layout

    Layout

    Block, inline, flex, grid and table geometry.

  • km-raster

    Rasterizer

    CPU painting and compositing, pixel by pixel.

  • km-font

    Fonts

    Font parsing, shaping inputs and glyph rasterization.

  • km-image · km-av1

    Images

    PNG, JPEG, GIF, WebP, SVG — and an AV1 decoder.

  • km-wasm

    WebAssembly

    Execution engine, checked against the full spec suite.

  • km-net

    Network & TLS

    Pure-Rust transport with no OpenSSL and no C underneath.