Compress PNG — Free, Private, No Upload
Shrink PNG files in your browser. Your file never leaves your device — no upload, no tracking, no analytics.
Drop PNG files here, or click to browse
Your file is processed entirely in your browser. We never see it.
No files yet. Drag a PNG above to compress it.
How it works
- Drop your PNG — Drag any PNG file into the box above. We support multiple files at once.
- Compress in your browser — The browser re-encodes each PNG using lossless Zlib optimisation. Nothing is uploaded — your file never leaves your device.
- Download the smaller file — Save the compressed PNG. The original is untouched.
Frequently asked questions
Frequently Asked Questions
How does PNG compression work in the browser?
We use the browser's native PNG encoder (canvas.toBlob) which already performs Zlib optimisation. For most PNGs this removes 5–20% of the file size with zero visual loss. Optional palette reduction (Lossy mode) can shrink further at a small fidelity cost.
Is my file uploaded?
No. Everything runs in your browser via JavaScript. The server never receives your image. We do not log, store, or share anything.
Does this work with transparent PNGs?
Yes. The compression preserves the alpha channel. We do not flatten or alter transparency.
Will the image quality change?
In Lossless mode (default), the image is pixel-identical. The encoder only re-orders the same data more efficiently. In Lossy mode, we reduce the color palette which can shift very subtle gradients.
Is there a file size limit?
25 MB per file. The compression runs in memory, so very large files may exhaust browser memory.
Can I compress multiple files at once?
Yes — drop multiple PNGs and they'll all compress in parallel. Use "Download all" to save them as a batch.