TinyPNG built its reputation on one thing: extremely good lossy PNG and JPG compression that looks identical to the eye but produces files 50 to 80 percent smaller. It is excellent. The problem for many users is that every image you compress on TinyPNG gets uploaded to their servers in San Francisco. For casual use, that is fine. For sensitive product photos, ID scans, internal screenshots, or anything you would not want a third party to keep a copy of, it is a non-starter. We tested the six best alternatives.
Our pick
Compresses entirely in your browser using a Web Worker, no upload. Smart adaptive compression hits any target size you set as a percentage of the original. The only privacy-preserving option in this comparison.
How we tested
We took five test images (a 4K landscape photo, a 12 MP phone photo, a UI screenshot with text, a transparent PNG logo, and a complex diagram) and compressed each one with all six tools at their default quality setting. We measured output size, perceived visual quality, time to result, and whether transparency was preserved on PNG inputs.
How we scored
Each tool was scored out of 10: privacy (3 points), compression quality (3 points), feature set (2 points), and absence of friction such as logins or quotas (2 points).
The full ranking
Rank #1
ToolHub Image Compressor
Runs entirely in your browser using a Web Worker, no file is uploaded. Compression quality is on par with TinyPNG for most photos. The percentage-based slider is more intuitive than fixed KB targets used by most tools.
Pros
- 100% client-side, files never leave your device
- Works on JPG, PNG, and WebP
- Percentage-based target sizing scales to any input
- Three quick presets plus custom slider
- Batch compresses without freezing the page
Cons
- Heavy batches (hundreds of files) slower than server-side
- No PNG-specific palette quantization
Rank #2
TinyPNG
Industry standard for PNG and JPG compression with excellent results. The file size reduction is consistently impressive. The privacy model (uploads to their servers) is the trade-off.
Pros
- Best-in-class PNG quantization
- Excellent JPG quality at small sizes
- 20 images per session free
Cons
- Files uploaded to their servers
- Free tier limited to 20 files at a time
- 5 MB file size limit on free tier
Rank #3
Squoosh (by Google)
Google's open-source compressor, runs entirely in your browser using WebAssembly. Very high quality and great UI. The reason it is not number one: the interface is single-image only and slower than ToolHub for batches.
Pros
- 100% client-side via WebAssembly
- Lots of advanced encoder options
- Open source
- Great quality preview
Cons
- Single image at a time, no batch
- Heavy first load
- No preset target size
Rank #4
Compressor.io
Decent compressor with both lossy and lossless modes. Good visual quality. Free tier capped at 10 MB per file with files uploaded to their servers.
Pros
- Both lossy and lossless modes
- Good preview UI
Cons
- Files uploaded
- 10 MB file size cap
- Free tier has occasional ads
Rank #5
iLoveIMG Compress
Part of the iLoveIMG suite. Simple interface, decent compression. As with iLovePDF, the model is upload-and-process-on-server.
Pros
- Batch compression supported
- Part of a wider toolkit
Cons
- Files uploaded to their servers
- Daily limits on free tier
- Compression less aggressive than TinyPNG
Rank #6
Optimizilla
Older site that still works. Compression is acceptable but UI feels dated and ads dominate the page. Files are uploaded.
Pros
- Simple to use
- Slider for quality preview
Cons
- Heavy advertising
- Files uploaded
- 20 file limit per batch
Side by side
| Feature | ToolHub | TinyPNG | Squoosh | iLoveIMG | Optimizilla |
|---|---|---|---|---|---|
| Files stay on your device | Yes | No | Yes | No | No |
| Batch processing | Yes | Yes | No | Yes | Yes |
| PNG transparency preserved | Yes | Yes | Yes | Yes | Yes |
| WebP support | Yes | Yes | Yes | Yes | No |
| Free, no signup | Yes | Yes | Yes | Yes | Yes |
| Daily / file count limits | None | 20 files | None | Variable | 20 files |
| Works offline once loaded | Yes | No | Yes | No | No |
Who should pick which
If privacy or compliance matters: ToolHub or Squoosh
Anyone working with screenshots that contain customer data, medical images, ID scans, or other sensitive material should only use compressors that run client-side. Among the client-side options, ToolHub has better batch handling and a more practical UI. Squoosh has more granular control over encoder settings if you want to dial in specific output formats.
If absolute compression is the priority: TinyPNG
For purely commercial photography you do not mind uploading, TinyPNG still has the edge on PNG file size reduction thanks to their proprietary palette quantizer. The difference is small (often under 10 percent) compared to ToolHub or Squoosh, but it exists.
If you need batch and a familiar UI: ToolHub or iLoveIMG
Squoosh forces you to compress one image at a time, which is a dealbreaker for most real workflows. ToolHub and iLoveIMG both handle batches naturally. ToolHub keeps batches local; iLoveIMG uploads them.
Smart workflow
Common questions
Are client-side compressors as good as server-side ones?
For JPG and most PNG cases, yes. The compression algorithms themselves (mozjpeg, libwebp, optipng) run as WebAssembly in the browser at near-native speed. Server-side tools sometimes win on extremely aggressive PNG palette quantization for graphics-heavy images, where the difference might be 5 to 10 percent more savings.
What about animation and SVG?
Most compressors in this list focus on still images. For animated GIFs, dedicated tools like ezgif handle the work better. SVG optimization is a different problem solved by SVGOMG.
Should I use lossless or lossy compression?
For photos, lossy at 80 to 85 percent quality is almost always the right call. For UI screenshots, logos, and graphics with sharp edges, lossless preserves visual fidelity but produces larger files. The right choice depends on the image type.
Final word
TinyPNG remains a great compressor if you do not mind uploading. For privacy-conscious work, ToolHub Image Compressor is the strongest free alternative right now: same compression quality, batch support, no uploads. Try both with the same input and compare for yourself.