How we judged
Five things matter in a free compressor: privacy (does your image leave your device?), real limits (file counts, sizes, watermarks), target-size control (can you hit exactly 100 KB?), format support, and batch handling. Here is how the well-known options stack up.
1. CrunchyPic — best for privacy and exact sizes
Yes, this is ours — and it exists because the tools above all annoyed us in some way. CrunchyPic compresses entirely in your browser: your images never upload to any server, there is no signup, no file-count caps, and no watermarks. Its standout feature is target-size compression — tell it "make this exactly 100 KB" and it binary-searches the quality for you (try it). It also handles JPG, PNG, WebP, AVIF, SVG, BMP, TIFF and HEIC, with a bulk compressor for batches. If privacy and precision matter to you, start here.
2. TinyPNG — best one-click simplicity
The classic. Drop in PNGs or JPGs and TinyPNG's smart lossy compression shrinks them impressively with minimal visible loss — it remains one of the best quality-per-byte engines available. The free tier caps how many images you can process at once and the maximum file size, and files are uploaded to their servers for processing. Great for a quick handful of images.
3. Squoosh — best for control freaks
Google's open-source web app runs entirely locally (good for privacy) and exposes every codec knob imaginable: multiple formats, quality sliders, resizing, and a live before/after comparison. The trade-off is complexity — it is one image at a time and the interface assumes you know what a quantizer table is. Excellent for learning and for tricky single images.
4. Compressor.io — best minimalist
Upload a JPG, PNG, GIF or SVG and get a smaller file back, with a choice of lossy or lossless modes. The interface could not be simpler, which is the whole appeal. Free-tier limits apply to file sizes and formats, and processing happens on their servers.
5. Optimizilla — best simple batch
Upload up to 20 images at once and adjust each with a quality slider while watching a live preview — a genuinely useful workflow the others lack. Compression quality is solid rather than spectacular. Files upload to their servers, and the site shows ads.
6. iLoveIMG — best all-in-one suite
Beyond compression, iLoveIMG bundles resizing, cropping, converting, and watermarking in one polished interface. Handy when your task spans several operations. The free tier limits batch sizes and file sizes, processing is server-side, and heavy users are nudged toward a paid plan.
7. Caesium — best desktop app
Prefer software over websites? Caesium is a free desktop compressor (Windows and macOS) with batch processing, folder monitoring, and quality previews. Nothing uploads anywhere since it runs locally. The interface looks dated and there is no target-size mode, but for offline batch work it is dependable.
Quick comparison
| Tool | Runs locally? | Target exact size? | Batch | Signup needed? |
|---|---|---|---|---|
| CrunchyPic | Yes | Yes | Yes | No |
| TinyPNG | No | No | Limited free tier | No |
| Squoosh | Yes | No | No | No |
| Compressor.io | No | No | Limited | No |
| Optimizilla | No | No | Up to 20 | No |
| iLoveIMG | No | No | Limited free tier | No |
| Caesium | Yes (desktop) | No | Yes | No |
What about phone apps?
App stores are full of "photo compressor" apps, and most follow the same playbook: free for three images, then a subscription popup — plus full access to your photo library. A browser-based tool like CrunchyPic does the same job with zero installs and zero permissions: open the page, compress, done. Unless you compress photos daily and want home-screen convenience, skip the apps.
Our honest take
For most people, most of the time: use CrunchyPic when you want privacy and an exact target size, TinyPNG when you want the simplest possible drop-and-done for a few files, and Squoosh when you want to fine-tune a single important image. Everything else on this list is a reasonable backup — none of them will steal your files, but check each one's current free-tier limits before a big job.