How does image compression work?

The tool re-encodes the image at a lower quality setting. You can control the quality with the slider to balance size and visual quality.

What formats can I compress?

PNG, JPG, and WebP images. JPG and WebP typically see the best compression ratios.

How much can I reduce the file size?

Typically 40-80% reduction depending on the original image and your quality setting.

Is my image uploaded to a server?

No. Compression happens entirely in your browser. Your images never leave your device.

Compress Images Online Free

Reduce image file size with adjustable quality

Select an image to compress

Frequently Asked Questions

What is the Online Image Compressor?

The Online Image Compressor is a free, privacy-first tool that reduces the file size of your images without noticeable quality loss. It works entirely inside your browser using the HTML5 Canvas API, so your photos are never uploaded to a remote server. Simply load a PNG, JPG, or WebP image, adjust the quality slider to find the ideal balance between size and clarity, and download the optimized result. There is no sign-up required, no watermark added, and no limit on the number of images you can compress. Whether you are optimizing assets for a website, shrinking attachments for email, or freeing up storage on your device, this tool makes it effortless.

When to Use the Image Compressor

Large image files slow down web pages, bloat email attachments, and eat into cloud storage quotas. Here are common situations where compression helps:

Optimizing hero images and photo galleries to improve website load times and Core Web Vitals scores.
Reducing the size of screenshots or photos before attaching them to emails or chat messages.
Preparing images for content management systems that enforce maximum file-size limits.
Shrinking high-resolution camera photos for faster sharing on social media.
Batch-compressing product images for an online store to save bandwidth and storage costs.

How It Works

After you select or drag an image onto the page, the browser's FileReader API loads it and draws it onto a hidden HTML5 Canvas element. The Canvas toBlob or toDataURL method then re-encodes the image at the quality level you choose. Lowering the quality slider tells the encoder to apply more aggressive lossy compression, significantly reducing file size while keeping visual fidelity surprisingly high. You can preview the compressed output and compare the before-and-after file sizes before downloading. Every step runs locally through the Canvas API — there is no server upload, no third-party processing, and no data collection. The result is fast, private image compression that works even when you are offline.