Image Compressor: Client-Side Image Compression, Now in Bulk
Image Compressor is a browser-based tool that reduces image file sizes without uploading anything to a server. Drop in one image or a whole batch, adjust quality, pick an output format, and download the results — all on your own device.
Update (August 24, 2026): the tool now handles bulk compression. Drop in dozens of images at once and it compresses every one with the same quality and format settings, shows a live before/after size for each, and lets you download them individually or grab everything together as a single zip.
The Privacy Case for Client-Side Compression
Most online image compressors work by sending your file to their server, processing it, and sending it back. That means your image — whatever it contains — is transmitted over the internet and touches someone else's infrastructure. For personal photos, confidential documents, or product images containing unreleased designs, that's a real concern. Client-side processing avoids the problem entirely: the file is read locally by your browser, processed in memory using the Canvas API, and exported back to your filesystem. Nothing leaves the tab.
How the Compression Works
When you load an image, the tool draws it onto an invisible HTML Canvas element at its original resolution. It then exports the canvas to a data URL using canvas.toDataURL(format, quality), where quality is a value between 0 and 1. The browser's built-in codec handles the actual compression — the same codec used when your browser displays images. The compressed result is shown side-by-side with the original so you can compare visually before downloading.
Output Formats
You can output as WebP, JPEG, or PNG. WebP almost always produces the smallest files at equivalent visual quality — if you're compressing images for a website, it's the best default choice. JPEG is the right pick for maximum compatibility with legacy software. PNG is lossless, so quality settings have minimal effect; it's mainly useful for converting other formats to PNG.
Quality Slider
The quality slider runs from 1% to 100%. At 80%, most photos are indistinguishable from the original to the naked eye while saving 50–70% in file size. Going below 60% introduces visible artefacts. The tool shows you the exact savings in bytes and percentage after each adjustment so you can find the sweet spot.
Drag and Drop, One File or Many
You can click the drop zone to browse for files or drag them in directly from your desktop or another browser tab — select a single image or a whole folder's worth at once. The tool accepts JPG, PNG, WebP, GIF, and BMP input, and each dropped file is queued and compressed independently as soon as it lands.
Bulk Mode
Every image in the queue shares the same quality slider and output format, so you set them once and the whole batch recompresses. Each image gets its own card showing the original size, the compressed size, and the percentage saved, so you can spot outliers — like a PNG that got bigger after conversion — before downloading. You can remove any single image from the queue or clear it entirely without affecting the rest.
Downloading Results
Each card has its own download button for grabbing one file at a time. For the whole batch, "Download All (ZIP)" packages every compressed image into a single archive using JSZip, built entirely in memory in the browser, and hands it to you as one .zip download.
Limitations
Because the tool uses the browser's built-in codecs, compression quality varies slightly between browsers and operating systems. Chrome and Edge on Windows tend to produce slightly different results than Safari on macOS for the same settings.