UlvixorImage Compressor
Upload an image and shrink it by adjusting the compression quality, with a live preview and file-size comparison. Compression happens with canvas directly in your browser — the image is never uploaded to a server.
How it works
- Select an image from your device using the file picker.
- Choose the output format (JPEG or WebP) and adjust the quality level with the slider.
- The image is drawn onto a hidden <canvas> and re-encoded with canvas.toBlob() at the chosen format and quality.
- The original size, compressed size, and reduction percentage are shown, along with a preview of the result.
- Download the compressed image with a single click.
Use cases
- Reduce photo file sizes before uploading them to a website or posting on social media.
- Optimize images to improve a website's load times.
- Compress screenshots or large images before sending them by email or chat.
- Visually compare the results of different quality levels before exporting.
Use cases
- Reduce photo file sizes before uploading them to a website or posting on social media.
- Optimize images to improve a website's load times.
- Compress screenshots or large images before sending them by email or chat.
- Visually compare the results of different quality levels before exporting.
Common mistakes
- Trying to compress a PNG image expecting a noticeable size reduction.PNG uses lossless compression and has no adjustable quality control like JPEG or WebP. If you need a significant size reduction, first convert to JPEG or WebP with this same tool.
- Compressing an image with transparency to JPEG and being surprised the background turns white.JPEG doesn't support an alpha channel. The tool automatically fills transparent areas with white before compressing; if you need to keep transparency, choose WebP as the output format.
- Thinking lowering the quality also reduces the image's dimensions (width and height).The quality control only adjusts how much visual information gets discarded when re-encoding, not the pixel dimensions. If you need to change dimensions, use the Image Size Calculator or an image editor.
Frequently asked questions
No. All compression happens in your browser using the canvas API (drawImage and toBlob). The image never leaves your device.
PNG uses lossless compression and doesn't have an adjustable 'quality' parameter like JPEG or WebP, so it doesn't offer a meaningful file-size reduction through this method. If you need to convert to PNG, use the Image Converter.
JPEG doesn't support transparency (alpha channel). When compressing to JPEG, the tool automatically fills transparent areas with a white background to keep them from turning black.
It depends on the original image and the quality level you choose. In general, lowering quality to 70-80% usually achieves a noticeable size reduction with minimal visible quality loss.
Alternatives
Services like TinyPNG or Photoshop's 'Save for Web' export do similar compression. This tool is convenient because it doesn't upload your image to any external server: compression happens with canvas directly in your browser, which matters if the image is private or sensitive.