Image Compressor
Compress images in your browser — no uploads
What is Image Compressor?
This image compressor re-encodes pictures with the Canvas API directly in your browser, letting you output WebP, JPEG, or AVIF at an adjustable quality level while showing the before and after file sizes and how much you saved. The image stays on your machine from start to finish — there is no upload step at all.
How to use Image Compressor
- 1Pick an image from your device.
- 2Choose an output format — at comparable quality, WebP is typically 25% or more smaller than JPEG.
- 3Drag the quality slider and watch for the point where file size and visual quality balance out.
- 4Click "Download" to save the compressed result.
Common errors and how to fix them
| Symptom | Cause | Fix |
|---|---|---|
| The compressed file is larger than the original | The source is already a heavily compressed JPEG or WebP, and re-encoding it at a higher quality setting adds bytes back. | Lower the quality value, or switch to a more efficient format (JPEG to WebP, for example). |
| A transparent background turns black or white | JPEG has no alpha channel. | Choose WebP, AVIF, or PNG when you need to keep transparency. |
Frequently asked questions
What quality setting should I use for image compression?+
For WebP and JPEG, a quality between 0.75 and 0.85 usually hits the sweet spot between file size and fidelity, with differences that are all but invisible. Images with large gradients or a lot of text are more sensitive to compression artifacts, so step through a few values and compare before committing.
Why is there no lossless optimization like in desktop tools?+
The browser's Canvas encoders only expose quality-based re-encoding; they do not perform lossless PNG optimization, which requires a dedicated implementation such as oxipng. This tool is built to be instantly usable with no upload. If you need to squeeze out the last few kilobytes, wire a dedicated compressor into your build pipeline.
Are my images uploaded to a server when compressing?+
No. Images are read into a bitmap through the browser file APIs and compressed locally by Canvas — the page never issues an upload request. Open your browser network panel and you will see that nothing is sent while you work.
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