Compress PNG (Lossless Re-Encode)
Lossless browser PNG re-encoder that strips ancillary chunks and retains truecolor transparency while guaranteeing the original is kept if not smaller.
Best solution
Local processing: Compress PNG (Lossless Re-Encode); Lossless truecolor preservation with ancillary metadata removal.
Choose a file to start. Nothing is uploaded.
Single still image. JPEG uses white behind transparency. Decoder notices
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Methodology & calculation rule
Deflate Re-Encode with Optimized Filter Heuristics → Compare Byte Payload
Browser canvas PNG export is strictly lossless. If the source PNG is already optimally compressed, the original file is preserved.
All image processing executes client-side within your browser sandbox via HTML5 Canvas and WebAssembly. No photographs, bitmaps, or metadata are ever uploaded to remote servers.
Output files are generated in-memory as local object URLs. Files must be smaller than 20 MB and under 24 megapixels.
Real-World Context & Technical Standards
Browser PNG Re-Encoding Characteristics
PNG encoding relies on 2D prediction filters followed by lossless Deflate (zlib) compression. The browser re-encodes pixel arrays cleanly, shedding redundant metadata structures without altering raw RGB values.
Truthful UI Contract
Unlike JPEG, standard browser canvas PNG export does not support lossy quality sliders. The tool truthfully reports whether fresh re-encoding reduced byte weight or whether the original file was already optimal.
Truecolor Alpha Preservation
The tool preserves full 32-bit RGBA Truecolor depth rather than forcing 8-bit palette quantization (which can cause severe color banding on smooth photographic gradients).
Related image tools
| Tool | Type | Format |
|---|---|---|
| HEIC to JPG | Diagnostic | JPEG |
| HEIC to PNG | Diagnostic | PNG |
| WebP to PNG | Diagnostic | PNG |
| PNG to JPG | Diagnostic | JPEG |
| JPG to PNG | Diagnostic | PNG |
Frequently Asked Questions
Why is there no quality slider for PNG?
PNG uses lossless compression. Standard browser canvas engines do not expose lossy quantization parameters for PNG.