Free Online Image Compressor: Reduce Size in KB / MB
Whether you need to compress images for web performance, email attachments, or strict upload limits, this free image compressor handles it entirely inside your browser. Shrink JPG, PNG, WEBP, and GIF files instantly — no file ever leaves your device. Use the quality slider for quick size reduction, or set an exact target file size (e.g., compress to 50KB or 2MB) and let the tool calculate the optimal output automatically.
How Image Compression Works
Image compression reduces file size by discarding redundant pixel data your eye cannot easily detect. JPG and WEBP use lossy compression — they analyze similar color regions and replace them with averages, achieving 60–80% file size reduction at quality settings of 70–85% with no visible difference. PNG uses lossless compression, which reorganizes pixel data without discarding any, resulting in smaller savings but zero quality loss. Our tool applies the correct algorithm per format automatically.
- JPG / WEBP: lossy, 60–80% reduction at quality 70–85%
- PNG: lossless index optimization, smaller savings, zero quality loss
- GIF: frame-level palette optimization, animation preserved
Target Size vs Quality Slider — Which to Use
Use the quality slider when you want fast results and visual quality control. Use target size mode when you have a hard limit imposed by a form, portal, or email system — for example, government ID upload portals often require files under 100KB or 200KB. The tool runs a binary search across quality levels to find the smallest file that still meets your size requirement.
Why Process Images Locally?
Unlike cloud-based compressors that upload your files to remote servers, this tool processes everything in your browser using the Canvas API and WebAssembly. Your images are loaded into browser memory, compressed, and made available for download — never transmitted over the internet. This makes it safe for sensitive files like ID scans, medical images, and confidential documents.