How browser-based compression works
The tool decodes each image, redraws it on a canvas at its original pixel dimensions and re-encodes it in the format you choose. JPEG and WebP use the quality setting; PNG is lossless and ignores quality. The original file is never modified or uploaded.
For each image you see the original size, the compressed size and the percentage saved. If a re-encode becomes larger than the source, the result says so instead of pretending the file shrank — a common outcome when a PNG screenshot is converted to another PNG.
Choosing an output format
| Format | Best for | Trade-off |
|---|---|---|
| WebP | Screenshots, store graphics, photographic backgrounds | Usually the smallest files; supported by modern browsers and stores. |
| JPEG | Photos and images without sharp UI text | Widely compatible; compression artefacts around text and edges. |
| PNG | UI with sharp text, flat colours, transparency | Lossless but often much larger; quality does not apply. |
Store upload limits differ. Google Play limits screenshots to 8 MB each; Apple's practical screenshot limit is around 10 MB. Always confirm current limits before uploading.
Quality settings in practice
- 90–100% — visually indistinguishable from the source for most screenshots, larger files.
- 75–90% — the usual sweet spot for store graphics and photos.
- 50–75% — useful when a hard file-size limit matters; check text for artefacts.
Compression cannot recover detail that is not in the source. Start from a high-quality export and compress once, rather than compressing an already compressed file repeatedly.
Batch workflow
- Drop up to ten images at once.
- Pick WebP, JPEG or PNG and adjust quality.
- Compare original and compressed sizes for every file.
- Download files individually or as one ZIP.
Images above roughly 20 megapixels are scaled down to stay within browser memory limits; the per-file result shows the output dimensions. All processing remains local.
Frequently asked questions
Are my images uploaded when compressing?
No. Compression uses the browser's canvas encoder. Files are read locally, held in memory only while the page is open and never sent to a server, analytics service or third party.
Does compression reduce image dimensions?
Normally no — the output keeps the source dimensions. Very large images above the browser memory limit are scaled down, and the result row shows the output size.
Which format gives the smallest file?
WebP usually produces the smallest file at a comparable visual quality, followed by JPEG. PNG is lossless and typically largest for screenshots, but best for sharp text and transparency.
Why is my compressed file larger than the original?
The source may already be efficiently encoded. Re-encoding a PNG or an already optimised screenshot can add bytes. Try WebP or a lower JPEG quality, or keep the original.
Can I compress several images at once?
Yes, up to ten images per batch. Download each result separately or all successful results as a ZIP archive.