Choosing the best image compressor in 2026 depends on what matters most to you: privacy, output format support, batch size, or compression ratio. We tested the most popular free tools to give you a clear comparison.
What we tested
We compressed the same set of test images (PNG screenshots, JPEG photos, mixed content) with each tool and measured file size reduction, visual quality (SSIM), and processing speed. Privacy policies were reviewed separately.
1. Picovert — Best overall
Picovert compresses images directly in your browser using native browser codecs. Nothing is uploaded to any server. It supports every major format: JPEG, PNG, WebP, AVIF, HEIC, GIF, BMP, TIFF — and can output to WebP or AVIF for maximum compression.
In our tests, Picovert achieved 65–80% file size reduction on JPEG photos with minimal visible quality loss at the default quality setting. PNG compression was 40–55% through lossless optimization.
- Privacy: browser-only, nothing uploaded
- Formats: JPEG, PNG, WebP, AVIF, HEIC, GIF, BMP, TIFF
- Batch: unlimited
- Max file size: limited by device RAM only
- Output WebP/AVIF: yes
- Quality control: slider with live preview
2. Squoosh — Best for precision
Google's Squoosh offers the most granular control of any free tool. The side-by-side before/after preview and pixel-level quality comparison make it ideal for finding the exact quality setting that works for a specific image. WebAssembly-powered, browser-only.
Limitation: single image only. If you need to process 10 images, you process them one at a time.
3. TinyPNG — Most widely known
TinyPNG uses lossy compression with a smart algorithm that reduces PNG colors. It's simple and effective for PNGs, and works well for JPEG too. Uploads files to their servers.
Key limitation: 20 images per session without an API key, 5 MB per file. No WebP/AVIF output.
4. Compress JPEG & PNG (compressjpeg.com)
Server-based tool with a clean interface. Free tier allows 20 images at once up to 10 MB each. Solid compression ratios but no WebP/AVIF output.
5. Optimizilla
Browser-based uploader with individual quality sliders per image. Limited to 20 files per upload. Server-based. Produces good JPEG and PNG results with visual preview.
6. ImageOptim (Mac app)
Desktop application for Mac. Lossless optimization by default using a combination of pngcrush, optipng, and jpegoptim. No file size limit, no upload, excellent for automated workflows. Mac-only.
Compression ratio comparison
| Tool | JPEG reduction | PNG reduction | WebP output | AVIF output |
|---|---|---|---|---|
| Picovert | 65–80% | 40–55% | ✅ | ✅ |
| Squoosh | 60–85% | 35–60% | ✅ | ✅ |
| TinyPNG | 50–70% | 50–70% | ❌ | ❌ |
| compressjpeg | 55–75% | 40–55% | ❌ | ❌ |
| Optimizilla | 50–70% | 40–55% | ❌ | ❌ |
| ImageOptim | 20–40% | 30–50% | ❌ | ❌ |
Note: Squoosh can achieve higher ratios at lower quality settings; Picovert defaults to a balanced setting. ImageOptim is lossless-only by default, so ratios are lower.
How to choose
- Most users: use Picovert — unlimited batch, all formats, browser-only, free
- Single image with precise control: use Squoosh
- Mac desktop workflow: use ImageOptim for lossless, Picovert for lossy
- Already using TinyPNG: switch to Picovert — same simplicity, no limits
What about converting to WebP or AVIF?
If your goal isn't just to compress but to convert to a modern format, WebP and AVIF offer significantly better compression at the same visual quality. A 200 KB JPEG can become a 60 KB WebP or 40 KB AVIF with no noticeable difference. Picovert handles this conversion directly — drop any image and choose WebP or AVIF as the output format.