JXL Convert — Free JPEG XL Converter & Viewer

Live: https://jpegxlconvert.com

A free, 100% client-side JPEG XL converter and viewer. Convert images to and from .jxl — and open .jxl files — entirely in your browser. Your files never leave your device: no upload, no server, no sign-up, no limits, no watermark.

Features

• Convert to JXL: JPG, PNG, WebP, GIF → JPEG XL (libjxl via WebAssembly).
• Convert from JXL: .jxl → PNG / JPG.
• HEIC support: open iPhone HEIC photos and convert them to JPG / PNG / JXL.
• Viewer: open and preview a .jxl file instantly, then save it as JPG/PNG.
• Private by design: everything runs locally in the browser. Nothing is uploaded.
• Multilingual: English, Español, Deutsch, Français, Русский — SEO-first with hreflang, canonical, structured data and Open Graph.

How it works

• JPG/PNG/WebP/GIF → JXL: decoded natively by the browser, encoded with a custom single-thread cjxl WASM build (libjxl) fed with raw PPM/PAM pixels — handles large camera photos (22 MP+) that the jSquash encoder WASM cannot (heap abort above ~12-16 MP). @jsquash/jxl remains as encode fallback.
• Lossless JPG → JXL: true bitstream transcoding via the same cjxl build (bit-identical, ~10-20% smaller).
• .jxl → PNG/JPG: decoded with @jsquash/jxl, re-encoded natively via <canvas>.
• HEIC: decoded in-browser, then converted.

Everything is static and serverless — deployable to any static host (this site runs on Cloudflare Pages).

Structure

/                 root: language auto-detect + redirect
/en /es /de /fr /ru   localized tool pages (full content + FAQ)
/assets/css       styles.css (shared)
/assets/js        app.js (converter engine), viewer.js
/assets/vendor    self-hosted JXL WASM codec
/sitemap.xml      multilingual sitemap with hreflang alternates

License

Free to use. The JPEG XL codec is provided by libjxl / @jsquash/jxl under their respective licenses.