At a glance
| Input | Any image the browser can open |
|---|---|
| Output | PNG, JPG or WebP |
| Quality | 40 to 100, default 90 (JPG and WebP) |
| Where it runs | Entirely in your browser — no file is uploaded to a server |
| Price | Free, with no account and no sign-up |
| Offline | Works with no connection after the first visit |
Which format for what
JPG for photographs. It throws away detail the eye is bad at noticing and gets small, but it has no transparency and it degrades a little every time it is saved.
PNG for anything with hard edges, flat colour or transparency — logos, screenshots, diagrams. It is lossless, which is why a photograph saved as PNG is often five times the size of the same picture as JPG.
WebP does both: lossy like JPG, transparent like PNG, and typically 25–35% smaller than a JPG of the same visual quality. Every current browser supports it. The reason not to use it is anything that has to open in older desktop software.
Transparency, and why it turns black
JPG has no alpha channel. Converting a transparent PNG to JPG means the see-through areas have to become something, and depending on the software that something is black, white, or whatever was underneath. That is the single most common surprise in image conversion.
If you need transparency, the target has to be PNG or WebP. If you need JPG, decide what colour the background should be before you convert, not after.
Converting does not undo compression
Turning a heavily compressed JPG into a PNG makes a large, lossless copy of a damaged picture. The blockiness is baked into the pixels; PNG preserves it perfectly and multiplies the file size doing it.
Convert from the best original you have. If all you have is the compressed version, converting will not rescue it.
Frequently asked questions
Why did my transparent background turn black?
Because you converted to JPG, which cannot store transparency. Convert to PNG or WebP instead, or flatten onto a chosen background colour first so the result is the one you wanted.
Is WebP safe to use now?
Yes for the web — every current browser reads it. Some older desktop applications and photo frames still do not, so send a JPG if the file is going somewhere you do not control.
Will converting JPG to PNG improve the quality?
No. PNG stores exactly what it is given, including the compression artefacts already in the JPG. You get a bigger file containing the same picture.
What quality setting should I use?
Around 80 is the usual sweet spot for JPG and WebP — visually hard to tell from the original at a fraction of the size. Below about 60 the flat areas start to band.
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