TinyPNG Alternative — Compress to an Exact KB Size, Free, No 500/Month Cap
TinyPNG is good at one thing — smart PNG/JPG compression — and its palette-quantization quality deserves the respect it gets. But its free API stops at 500 compressions a month, its web tool handles about 20 images per session with a 5 MB per-file cap, everything is uploaded to their servers, and it has no answer at all for the most common real-world request: “make this photo under 200 KB”. OnyxPDF’s Compress Image does all of that, locally.
| OnyxPDF | TinyPNG (free) | |
|---|---|---|
| Monthly / session cap | None | 500 compressions/month (API); ~20 images per web session |
| Per-file size cap | None (device memory is the limit) | 5 MB |
| Compress to an exact KB target | Yes — binary search to your target (200 / 100 / 50 KB…) | No target-size mode |
| PNG palette compression | Yes — median-cut palette encoder | Yes — its signature strength |
| Resize | Built in, with social presets | Paid API only |
| Upload required | No — runs in your browser | Yes — files processed on their servers |
| Developer API | No | Yes — that is their product |
| Price | Free | Free tier; Pro $39/year, Ultra $149/year |
The exact-KB gap
The most common compression job on earth is not “make it smaller” — it is “this form refuses anything over 200 KB”. Portals for visas, exams, jobs and IDs all work this way. TinyPNG gives you one output size and no dial to aim with; hitting a KB target there means resizing by trial and error. Here you type the target and the tool binary-searches quality — then dimensions, if needed — until the output fits, and shows you the verified final byte count.
Same trick, no meter
TinyPNG’s quality comes from palette quantization — reducing a PNG to its 256 most important colours. OnyxPDF implements the same idea with a median-cut palette encoder written for the browser: a 1.5 MB photo PNG came out at 335 KB in our own testing, dimensions untouched. The difference is the meter: no 500-a-month counter, no account, and the photo never leaves your device to be counted.
Where TinyPNG still wins
If you are a developer who needs compression inside a build pipeline or a backend, TinyPNG’s API is the product — OnyxPDF has no API and is not trying to be one. For humans compressing photos in a browser, the caps and the missing KB mode are the story.
Questions
How do I compress an image to 200 KB without TinyPNG?
Open Compress Image, choose “Compress to exact KB”, type 200, and compress. The tool iterates until the output is at or under 200 KB and shows you the exact size.
Is the PNG quality as good as TinyPNG’s?
Both use palette quantization, so results are comparable: large savings on photos and screenshots, with possible banding in fine gradients at very low colour counts. The colour-count slider here lets you choose your own trade-off.