Lossless Image Optimizer

What this optimizer changes

For PNG, the tool may recompress the existing filtered scanlines with the browser’s DEFLATE implementation. It verifies that the decompressed data is identical before using the smaller stream. It can also combine consecutive IDAT chunks and remove text, compressed-text, international-text and modification-time chunks. Image dimensions, palette, transparency and colour-management chunks are preserved.

For JPEG, the compressed image scan is copied exactly. The tool removes optional COM comment segments and bytes after the end-of-image marker. It preserves EXIF, orientation, ICC colour data and the encoded DCT coefficients. This avoids the generation loss caused by opening a JPEG in a canvas and saving it again.

Exact limits

• Static PNG and JPEG only; WebP, GIF, AVIF and animated PNG are not accepted.
• Up to 10 files per batch.
• Up to 20 MiB and 24 megapixels per file.
• A file that cannot be reduced safely is returned unchanged, so a 0% result is normal.
• Downloads keep the original format and add -optimized to the filename.

Privacy and funnel storage

All parsing, compression and downloads happen in your browser. The files are not sent to our servers, placed in the URL or uploaded to a server. In the optional multi-step funnel, source files are kept in this browser’s IndexedDB for up to 30 minutes so they can survive page navigation. Starting over or expiry removes that temporary draft.

When to use lossy compression instead

Lossless optimization usually saves less than resizing or lossy compression because it must preserve every decoded pixel. Use it for interface assets, archival handoffs and images that must not gain new JPEG artifacts. If a much smaller web image matters more than exact pixels, use an image compressor or resize the image first.