DETERMINISTIC
PIXEL DIFF.
AGENT-IN-THE-LOOP
VERDICTS.

RUST, WASM, AND JS DIFF CORES. SSIM AND GMSD METRICS. JEST, VITEST, AND BUN MATCHERS. AN AGENT THAT HANDS AMBIGUOUS DIFFS TO CLAUDE CODE, CURSOR, OR CODEX. NO SAAS. NO API KEY. MIT.

INSTALL
npm install @blazediff/core
$ npx @blazediff/cli a.png b.png --interpret
BASELINE
baseline
CURRENT
current

WHY BLAZEDIFF

01

FAST, DETERMINISTIC PIXEL DIFF

Pure-JS core ~1.5x faster than pixelmatch. Rust binary 3 to 4x faster than odiff, up to 8x on 4K. Wasm build (~32 KB, v128 SIMD) ~5x faster than pixelmatch on 4K in the browser. Reproducible on any machine.

02

FULL CONTROL, ZERO VENDOR LOCK-IN

No SaaS, no API keys, no per-snapshot pricing. Screenshots never leave your machine. Self-hosted from your CI. MIT licensed.

03

AGENT-READY

When the heuristic can't decide, the agent hands a small region tile to Claude Code, Cursor, or Codex for judgment. Resume from a checkpoint.

BENCHMARKS

REPRODUCIBLE FROM THE REPO. SAME FIXTURES, SAME HARDWARE (M1 MAX), HYPERFINE-MEASURED.

JS CORE VS PIXELMATCH VS WASM CORE4K · IO EXCLUDED · 50 RUNS
pixelmatch302ms
@blazediff/core212ms
@blazediff/core-wasm51.75ms
NATIVE BINARY VS ODIFF4K · IO INCLUDED · 25 RUNS
odiff1.19s
@blazediff/core-native294ms

FULL TABLE IN BENCHMARKS.MD AT THE REPO ROOT. EVERY ROW HAS A FIXTURE AND A METHODOLOGY NOTE.

USED BY

VitestVitestShopifyShopifyAnt DesignAnt DesignAnt Vis GAnt Vis GAnt Design XAnt Design XGPT-VisGPT-VisVegaVegaApexChartsApexCharts

THE STACK

ONE MONOREPO. FOUR LAYERS. INSTALL ONE PACKAGE OR THE WHOLE STACK.

SURFACES
@blazediff/agentVisual regression that your coding agent runs. Onboards Claude Code, Cursor, Codex. No API key required.
@blazediff/cliCommand-line interface for image comparison.
@blazediff/uiUnstyled web components for displaying image differences.
@blazediff/reactReact components for image comparison.
TEST HARNESSES
@blazediff/jestJest matcher for visual regression testing.
@blazediff/vitestVitest matcher for visual regression testing.
@blazediff/bunBun test matcher for visual regression testing.
@blazediff/matcherCore matcher logic for visual regression testing.
METRICS
@blazediff/ssimSSIM (Structural Similarity Index) for CI visual testing. ~25% faster than ssim.js; Hitchhiker variant ~70% faster.
@blazediff/gmsdGMSD (Gradient Magnitude Similarity Deviation) metric for CI visual testing. Single-threaded, allocation-free hot path.
@blazediff/objectObject comparison with path tracking, cycle detection, and CREATE/REMOVE/CHANGE types. ~55% faster than microdiff.
FOUNDATION
@blazediff/corePure-JS pixel diff with two-pass block optimization. ~1.5x faster than pixelmatch with identical accuracy.
@blazediff/core-nativeSIMD-accelerated Rust binary. 3 to 4x faster than odiff, up to 8x faster than pixelmatch on 4K.
@blazediff/core-wasmSame Rust algorithm, wasm32 v128 SIMD. ~5x faster than pixelmatch on 4K. Browser, edge, any wasm host.
READ DOCSTRY THE AGENT →BROWSE EXAMPLESGITHUB