ODiff

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Introduction

ODiff describes itself as ‘the fastest (one-thread) pixel-by-pixel image difference tool in the world’ (vendor claim). It compares two images in milliseconds and is designed for significantly similar images such as screenshots, photos and AI-generated images.

Originally written in OCaml, it is now written in Zig with SIMD optimisations for SSE2, AVX2, AVX512 and NEON. Features include cross-format comparison (for example JPG against PNG), support for PNG, JPEG, WebP and TIFF, comparison of images with different layouts, anti-aliasing detection and ignore regions. A Node.js API (odiff-bin) makes it easy to use from JavaScript test tools, and Visual Regression Tracker offers it as a comparison engine.

Release 4.5.0 shipped in July 2026.

In the quality loop it speeds up screenshot comparisons in large visual suites.

The source code is at dmtrKovalenko/odiff on GitHub under the MIT licence, with about 3,300 stars; the most recent commit was on 13 October 2026.

Features

1. Native speed: SIMD-optimised Zig.
2. Cross-format: Compare different image formats.
3. Different layouts: Handles size differences.
4. Anti-aliasing detection: Fewer false positives.
5. Node.js API: odiff-bin package.

Pros

1. Very fast: Good for large suites.
2. Free to use: Open source under the MIT licence, so the core tool costs nothing to use.
3. Actively maintained: The repository had commits as recent as 13 October 2026.
4. Community: About 3,300 GitHub stars.

Cons

1. Comparison only: No baseline workflow.
2. Native binary: Platform builds required.

Usage and Links (Example)

npx odiff-bin base.png current.png diff.png --threshold 0.1

Resources:

• ODiff website

Pricing

ODiff is free and open source under the MIT licence.

Recommended for?

1. Teams with large screenshot suites needing fast diffs.
2. Not a fit if you need a review UI.

Conclusion

ODiff is a fast, maintained image diff engine for visual testing pipelines.

On CheckOps, ODiff is filed under the End-to-end & functional stage. Related tools listed here include pixelmatch, jest-image-snapshot, Visual Regression Tracker, reg-suit, BackstopJS and Argos. Before choosing, compare them on licence, supported languages and platforms, hosting model, and how well each fits your existing CI pipeline. Facts on this page were checked against the official website, documentation and repository on 11 November 2026; statements the vendor makes about its own product are marked as vendor claims.