TinyPNG, Squoosh, ShortPixel, and ImageOptim each solve a slightly different slice of the same problem. Komprs is the one that drops the 20-file session cap without giving up the split-slider viewer. That combination explains most of the design choices below. The rest of this page covers how the category is normally built, what each alternative does better, and where Komprs forces trade-offs worth knowing before you paste in a 400-image catalog.
How browser-based image compressors are normally built
There are two reference shapes. The first is a server-side pipeline (TinyPNG, ShortPixel, Compressor.io): the browser uploads each file over HTTPS, a backend runs pngquant, mozjpeg, or libwebp, and the compressed result streams back. The second is a client-side pipeline (Squoosh, Optimizilla, Komprs): the image is decoded into a <canvas> element, re-encoded with canvas.toBlob(type, quality), and never leaves the tab. Squoosh ships WASM builds of mozjpeg, OxiPNG, and libwebp so the encoder on your device matches the server-side tools byte for byte.
Most "browser-based" compressors you find through Google are actually the first shape. The marketing copy says "compress in your browser" because the UI is in your browser. The encoding itself happens on someone else's GPU.
The four design choices that split the category
The category sorts cleanly along four axes.
Where the encoder runs. Server-side encoders (TinyPNG, ShortPixel) get faster CPUs and tuned codec builds. Client-side encoders (Squoosh, Komprs) get privacy and offline use. There's no middle ground. Bytes either cross your network boundary or they don't.
Batch support. Squoosh handles one image at a time, by design. TinyPNG caps the free web UI at 20 images per session and 5 MB per file. ImageCompressor.com caps at 20 images. Optimizilla also caps at 20. Komprs has no cap because there is no server to throttle.
Visual diff. Squoosh and Optimizilla both ship a side-by-side or split-slider viewer. TinyPNG does not. You get a percentage saved and a download link, and you trust that the encoder didn't over-compress your gradient. ImageOptim (the macOS app) shows file size deltas only.
Output format flexibility. Squoosh exposes JPEG, PNG, WebP, AVIF, and JPEG XL with separate quality dials. TinyPNG and ShortPixel output the same format you put in. Komprs offers JPEG, PNG, and WebP through the canvas path, no AVIF, no JPEG XL.
| Tool | Where it runs | Batch | Visual diff | WebP out | Session cap |
|---|---|---|---|---|---|
| Squoosh | Client (WASM) | 1 at a time | Split slider | Yes | None |
| TinyPNG | Server | Up to 20 | No | Pro tier only | 20 / 5 MB |
| Compressor.io | Server | Up to 10 | Before/after | Yes | 10 MB free |
| ImageCompressor.com | Server | Up to 20 | Thumbnails | No | 50 MB total |
| Optimizilla | Server | Up to 20 | Split slider | No | 20 files |
| Komprs | Client (Canvas API) | Unbounded | Split slider | Yes | None |
What Squoosh, TinyPNG, and Optimizilla each do better
Squoosh wins on encoder fidelity. Because it ships WASM builds of mozjpeg 4.x and libwebp 1.3, a Squoosh JPEG at quality 80 is a few percent smaller than a Komprs JPEG at quality 80 for the same input. The browser's built-in canvas.toBlob('image/jpeg', 0.8) uses whatever the platform supplies, which on Chromium is libjpeg-turbo without mozjpeg's trellis quantization. If you're squeezing the last 4 KB out of a hero image for a Lighthouse score, open Squoosh.
TinyPNG wins on PNG quantization. TinyPNG's server runs pngquant with a perceptual model that converts true-color PNGs into 8-bit indexed PNGs with a custom palette. That can cut a 1.2 MB UI screenshot to 280 KB with no visible degradation. The Canvas API has no equivalent. A PNG re-encoded through canvas stays 24-bit and gets nowhere near that ratio. Komprs strips metadata and lets Deflate find repeats. That's the ceiling.
Why doesn't Komprs just use pngquant in WASM the way Squoosh does?
We picked the native Canvas path over a WASM bundle because the bundle adds about 2.1 MB to initial page weight before a single image is touched. For a tool you open, run once, and close, that tax is hard to justify.
Optimizilla wins on the slider UX. It shows the original and compressed bitmap stacked, with a numeric quality field per image. You can over-compress one image in a batch of 30 without affecting the others. Komprs applies one quality setting to the whole queue. Per-image override is on the roadmap but not in v1.
The trade-offs you inherit with Komprs
Picking Komprs means accepting the Canvas API as your encoder. Canvas doesn't expose progressive JPEG encoding, chroma subsampling controls, or the kind of two-pass quantization mozjpeg does. You get what Chromium, Firefox, or Safari ships in their native image-write path.
That's a real ceiling, worth stating plainly. A 2.4 MB DSLR JPEG run through Komprs at quality 80 lands around 1.1 MB. The same file through Squoosh's mozjpeg at quality 80 lands around 980 KB. Through TinyPNG it comes back at roughly 850 KB. The order is consistent across formats: client-native is the largest, WASM-native is in the middle, server-tuned is the smallest.
In exchange you get the rest of the matrix. No upload step, so a 600 MB folder of camera raw exports stays a local operation. No session cap, so the batch is bounded only by available RAM. No account, so you don't get a one-week trial that locks you out on the eighth day.
The other concrete trade-off is HEIC. iPhone photos saved as .heic can't be decoded by canvas in Chrome on Windows or Linux. Safari can decode them. Chrome on macOS can decode them through the platform image I/O. The behavior is uneven enough that we treat HEIC as out of scope. Convert to JPEG first with Preview, Shortcuts, or sips on macOS.
What about AVIF output?
The Canvas API supports image/avif encoding in Chromium 102 and later, but not in Firefox or Safari yet (as of May 2026). Until the encoder is universal, shipping AVIF as a Komprs output would mean some users get a working button and others get an error toast. So we waited.
When to use a server-side compressor instead
Reach for TinyPNG when the input is a small batch of PNG screenshots and the size delta is the only thing you care about. ShortPixel is the right call if you have an established WordPress workflow and want a media-library plugin. Squoosh fits when you're tuning a single hero asset and want format-by-format comparison. For a quick one-off under 10 MB, Compressor.io is fine.
Use Komprs when one of three things is true: the files can't leave your machine, the batch is larger than 20, or the input mix is JPEG, PNG, and WebP together and you want one tool that handles all three with the same slider.