Compress images without visible quality loss
Shrink JPG, PNG and WebP files while keeping them looking sharp.
- 1Add files
- 2Configure
- 3Download
Drop your images to compress
or click to browse · up to 10 MB each · max 50 files
What this tool does
Reduce image file size for sharing or publishing. Choose whether to keep every pixel or allow a smaller encoded result.
How to use it
- Add one or more supported images.
- Choose Smallest file or Lossless, then select an output format. When relevant, adjust quality and the background used for JPG.
- Compare the output sizes and download the files you want.
Understand the controls
- Lossless
- PNG is repacked without changing its decoded pixels. For JPG and WebP, lossless mode retains the original file rather than re-encoding it.
- Format and quality
- JPG suits photographs, PNG preserves transparency and sharp edges, and WebP often balances size and quality. Quality affects lossy output.
Example
For a screenshot with small text, try PNG first. For a large photo with no transparency, compare JPG and WebP at a moderate quality setting.
Files and limits
Up to 50 files in one batch. An already efficient file may not shrink further; compare the actual byte sizes before replacing an original.
Private by design
Files are processed in your browser and never uploaded.
Batch-friendly
Process up to 50 files in one go with identical settings.
Free, no sign-up
No account, no watermark, no limits on how often you use it.
Frequently asked questions
Are my images uploaded to a server?
No. btools compresses images entirely inside your browser using the Canvas API. Your files never leave your device.
Which format should I choose?
JPG gives the smallest size for photos. PNG keeps sharp edges and transparency, and is best for graphics, screenshots and logos. WebP is usually the smallest overall and is supported by all modern browsers.
How is a PNG made smaller?
PNG has no quality to trade away, so btools rebuilds it more efficiently: it picks the best of the five PNG filters for every scanline and re-compresses the result at maximum deflate. When the image already uses 256 colours or fewer it is also stored as a palette, which is a large saving. All of this is lossless — the pixels come out identical.
What does Lossless mode guarantee?
That not a single pixel changes. For PNG, btools re-packs the file without touching the image data. For JPG and WebP there is no way to re-compress losslessly in a browser, so btools keeps your original file exactly as it is rather than pretending to shrink it.
Can compressing make my file bigger?
No. If re-encoding cannot beat your original, btools returns the original file untouched — in every mode.