Image Compressor

How to compress images without uploading – complete guide

DocUpLift’s image compressor uses the HTML5 Canvas API to re‑encode your image at a lower quality setting and strips out all non‑visible metadata (EXIF, GPS, thumbnails). This typically reduces file size by 40‑80% while maintaining excellent visual fidelity. Because everything happens on your device, you can compress sensitive photos without worry.

Unlike many online tools that secretly upload your files to a server, DocUpLift never transmits any data. The compression is done locally, using your computer’s CPU. This means it’s not only private but also extremely fast – even with large 50MB images. The result is a clean, optimized image ready for email, web, or storage.

You can adjust the quality slider to find the perfect balance between file size and appearance. For JPEGs, a quality of 70‑80% often yields huge savings with no visible difference. For PNGs, we automatically convert to JPEG when you lower the quality below 90% because PNG is a lossless format and doesn’t support variable quality. This gives you the smallest possible file size.

Our image compressor supports JPG, PNG, WebP, and even BMP/GIF. After compression, you can download the new file instantly. There’s no limit on the number of compressions – use the tool as many times as you like, completely free.

We also preserve the image dimensions. Unlike other compressors that might downsample your photo, we keep the exact pixel width and height. Only the encoding is optimized. This is perfect for photographers, web designers, and anyone who needs high‑res images without the large file size.

Privacy is at the core of DocUpLift. We don’t ask for your email, we don’t show ads, and we don’t track you. Every compression is 100% private. Try it now – select an image and see the difference.

Technical details: how it works

When you select an image, the browser reads it as a data URL. We then draw it onto a <canvas> element. The canvas allows us to export the image as a new file with a specific quality setting using the toBlob() method. For JPEG export, the quality parameter (0‑1) directly controls compression. For PNG, we can reduce file size by reducing the number of colors? No – PNG is lossless, so we switch to JPEG when the quality is below 90. This is a smart fallback that most users appreciate.

We also strip metadata. EXIF data, camera info, location, thumbnails – all are removed during the re‑encode. This alone can save hundreds of kilobytes. The result is a clean, web‑optimized image.

DocUpLift’s compressor is also safe: we never store or log anything. No cookies, no sessions. You can verify this by opening your browser’s developer tools – you’ll see zero network requests after the page loads.

We hope you enjoy using our tool. If you have feedback, please reach out on GitHub. We’re committed to keeping DocUpLift free and private forever.

If you need to adjust image dimensions instead of compressing, try our Resize Image tool. You can also remove unwanted areas before compressing using the Crop Image tool. For format conversion, use our WebP Converter.