Free Image Format Converter (WebP / AVIF / PNG / JPEG)

Yes, it is completely free with no usage limits, no watermark, no signup, and no paywall. Because everything runs locally in your browser using the open-source jSquash codecs, there are no server costs to pass on to you. You can convert as many PNG and JPEG files to WebP, AVIF, or PNG as you like without an account. jSquash itself is released under the Apache 2.0 license, and the underlying codecs (MozJPEG, libwebp, libavif, oxipng) are maintained by Mozilla, Google, and the WebM and AOMedia communities.

No. This converter runs 100 percent in your browser using jSquash, the WebAssembly image codecs derived from Google Squoosh. When you select a file, it is read into memory and decoded and re-encoded entirely on your own device. Nothing is uploaded, nothing is stored, and nothing is logged. You can confirm this by opening your browser DevTools, switching to the Network tab, and watching that no upload request is made while you convert. This makes the tool safe for private photos, confidential screenshots, and unreleased design work.

No installation, extension, or desktop app is required. The converter is a web page that loads the jSquash WebAssembly codecs into your browser on demand. The first time you convert to a given format, the matching WASM module (for example libavif for AVIF or libwebp for WebP) is downloaded once and then cached. After that, conversions happen instantly and locally, with no native software, no command-line tools, and no sign-in.

The first time you convert to a particular format, your browser downloads the corresponding jSquash WebAssembly codec, which is a one-time cost of a few hundred kilobytes. Once that module is fetched and cached, subsequent conversions to the same format are fast and run entirely offline. AVIF is an exception: even after the codec loads, AVIF encoding stays computationally heavy because it uses the AV1 codec to analyze the image thoroughly, so large images can take a few seconds regardless of caching.

Yes. After the first load fetches the jSquash WASM codecs, conversion runs with no network connection, because all encoding and decoding happens on-device. It also works on mobile browsers, though large images may be slower and use more memory there since the WebAssembly encoder runs single-threaded inside the browser tab. For very large photos on a phone, WebP is a good choice because it encodes much faster than AVIF while still beating JPEG and PNG on file size.

WebP, encoded here with libwebp, is a widely supported modern format that typically produces files 25 to 35 percent smaller than JPEG at similar quality, and it is supported by every current browser. AVIF, encoded with libavif, is newer and usually compresses even better, often 20 to 50 percent smaller than WebP, but it is slower to encode and slightly less universal on older devices. As a rule of thumb: choose WebP for the best balance of compatibility and size, and choose AVIF when you want the smallest possible file and your audience uses modern browsers. For maximum coverage, many sites serve AVIF with a WebP or JPEG fallback.

For lossy targets (WebP and AVIF), the quality slider maps directly to the encoder quality parameter from 1 to 100. Higher values preserve more detail but produce larger files; lower values compress harder at the cost of visible artifacts. A good starting point for photos is around 75 to 80, which usually looks visually identical to the original while saving a large amount of space. PNG output is lossless, so the slider is hidden and no visual quality is lost, although re-encoding a JPEG to PNG cannot recover detail JPEG already discarded. Use the before-and-after preview and the live size comparison to find the sweet spot for each image.