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

RUST 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

CURRENT

WHY BLAZEDIFF

DETERMINISTIC

Pure-JS core ~1.5x faster than pixelmatch. Rust binary 3 to 4x faster than odiff, up to 8x on 4K. Reproducible on any machine.

LOCAL

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

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 PIXELMATCH4K · IO EXCLUDED · 50 RUNS

pixelmatch302ms

@blazediff/core212ms

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.

REGION-TILE HANDOFF

OTHER TOOLS HAND A REVIEWER THE FULL PAGE. BLAZEDIFF HANDS YOUR AGENT THE CROP THAT CHANGED. 10X TO 100X FEWER BYTES. 10X TO 100X FEWER TOKENS.

full-page baseline.png

Full-page baseline screenshot with all diff regions overlaid

1328×1228 px10 diff regions~ 2.4 MB · ~ 1.6M pixels

diff/00.png · region tile

Region tile cropped to the changed bounding box

199×89 px1 region~ 18 KB · ~ 17K pixels

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.

USED BY

READ DOCS TRY THE AGENT →BROWSE EXAMPLES GITHUB

DETERMINISTICPIXEL DIFF.AGENT-IN-THE-LOOPVERDICTS.