Image Converter & Compressor — WebP, AVIF, JPEG, Local Only

The one tool category where local processing really matters

Every mainstream online image compressor works the same way: you upload the file, a server re-encodes it, you download the result. For a screenshot of a bug, that is fine. For a photograph of a person, a scan of a document, or a product shot under embargo, you have just handed a copy to a company whose retention policy you have not read.

None of that happens here. The browser decodes the image onto a canvas and re-encodes it with its own built-in encoders. The file never leaves your machine, which you can verify by disconnecting from the network and converting anyway.

Which format

WebP — the safe default. Typically 25–35% smaller than a comparable JPEG, supported everywhere that matters, and fast to encode.
AVIF — the smallest files, often dramatically so, with excellent quality at low bitrates. Encoding is slow, and browser support for encoding is narrower than for decoding, so it may be unavailable here even though your browser can display AVIF.
JPEG — universal, no transparency, still reasonable for photographs when compatibility is the priority.
PNG — lossless, keeps alpha. Correct for screenshots of text, logos and anything with sharp edges. Wrong for photographs, where it produces enormous files.

Quality is not a percentage of anything

The quality slider is an encoder parameter, not a proportion of the original. At 80 most photographs are visually indistinguishable from the source at a fraction of the size; below about 60 artefacts become visible in flat areas and around text. PNG ignores the setting entirely, because lossless has no quality dial.

Metadata is removed, deliberately

Re-encoding through a canvas discards EXIF data, which includes the GPS coordinates a phone camera writes into every photo. That is almost always what you want before publishing an image, and it is worth knowing it happens. The trade-off: orientation is baked into the pixels rather than left as a tag, so a correctly rotated image stays correctly rotated.

Large files

Everything is held in memory, so very large images — beyond roughly 8,000 pixels on a side — can exhaust a mobile browser. Setting a max width is the fix, and it is usually the right thing anyway: serving a 6,000px photo to a 390px phone screen wastes most of the bytes you just spent time optimising.

Questions people actually ask

Are my images uploaded anywhere?

No, and this is the one tool category where that difference is enormous. Images are decoded onto a canvas and re-encoded by the browser. Every mainstream online image compressor uploads your file to a server; if the photo contains people, documents or anything private, that is a meaningful difference.

Which format should I choose?

AVIF gives the smallest files and is now widely supported, but encoding is slow. WebP is the safe default — clearly smaller than JPEG with universal modern support. Keep PNG only when you need lossless or an alpha channel that must not be touched.

Is any metadata removed?

Yes, as a side effect of re-encoding. EXIF data — including GPS coordinates from a phone camera — does not survive the canvas round trip. That is usually what you want before publishing an image, but it also means orientation is baked in rather than left as a tag.