No upload, 100% local, no account

Convert images between JPG, PNG and WebP

Switch formats locally: no upload, no privacy concerns. Transparency is preserved for PNG and WebP; converting to JPEG flattens it onto white.

How Convert images works

Image Converter switches a JPEG, PNG or WebP file to one of the other two formats using the same image codecs your browser already ships for every picture on the web. There is no WebAssembly module to fetch first: drop a file, pick the output format, and the converted file is ready to download in a fraction of a second. The conversion runs on an OffscreenCanvas inside a Web Worker, so nothing is ever sent to a server and the page stays responsive while a batch of files is processed.

The tool also reads AVIF, GIF, BMP and TIFF files as input, even though it only writes JPEG, PNG or WebP: those three are the formats every browser, photo editor and content management system can open without a plugin. JPEG has no transparency channel, so converting a PNG or WebP with transparent pixels to JPEG fills the transparent areas with white before saving, and the tool shows that warning before you download anything. Converting to PNG or WebP keeps the alpha channel exactly as it was.

Written by Bastien Sulyan

How to use Convert images, step by step

  1. Drop one or more JPEG, PNG or WebP files onto the upload area, or click to browse.
  2. Choose the target format: JPEG, PNG or WebP.
  3. For JPEG or WebP output, set the quality with the slider. PNG is always lossless and has no quality setting.
  4. If you are converting to JPEG and the source image has transparency, read the warning: transparent areas will be filled with white.
  5. Click Convert. Each file is decoded and re-encoded locally in a Web Worker.
  6. Click Download to save each converted file to your device.

Common use cases

  • A blog author needs a WebP version of a PNG screenshot to cut page weight before publishing, without touching the dimensions.
  • A print shop received a WebP product photo from a supplier and needs a JPEG their layout software can actually open.
  • A developer converts a batch of PNG icons to WebP to compare the resulting file sizes before deciding what to ship.
  • Someone saved a WebP image from a page that only offers that format and needs a plain JPEG copy for a document or a print form.

Frequently asked questions

Does converting my image upload it anywhere?

No. The file is read from your disk, decoded, and re-encoded entirely inside a Web Worker in this browser tab. Open your browser's Network panel while converting and you will see no request carrying image data.

Why can I only convert to JPEG, PNG or WebP, and not AVIF?

The tool can read AVIF files as input because browsers decode them natively, but canvas-based AVIF encoding is not consistently supported across browsers today. Rather than offer an output that silently fails or produces a broken file in some browsers, AVIF is left out of the output list. If you specifically need an AVIF output, the Resize tool's jsquash WebAssembly encoder supports it.

What happens to transparency when I convert to JPEG?

JPEG has no transparency channel. Any transparent or partially transparent pixel is filled with white before the file is saved, and the tool displays a warning whenever JPEG is the selected output so you know before you download. Converting to PNG or WebP instead keeps the original alpha channel untouched.

Is this the same engine as the Resize or Compress tools?

No, and that is deliberate. Resize and Compress lazy-load the jsquash WebAssembly codecs (mozjpeg, oxipng, webp) for a higher-quality re-encode, at the cost of a one-time download. This converter uses your browser's built-in image codecs instead: nothing to download, an instant conversion, with slightly different compression characteristics on JPEG and WebP output than the WASM encoders.

Can I convert several files at once?

Yes. Drop or select multiple files and each one is converted in turn, with its own progress shown, then offered as a separate download.

Does it work without an internet connection?

Yes, fully. Unlike the WASM-based image tools, there is no codec to download the first time you use it: once this page itself has loaded, the conversion runs from code already in your browser and keeps working with no network connection at all.