Image Format Converter — PNG, JPEG, WebP, AVIF Local
Convert images between PNG, JPEG, WebP, and AVIF in your browser. Steps: choose a file, pick the target format, set quality (and a JPEG background if needed), then download. Example: turn a transparent PNG screenshot into WebP for a faster page — files stay on your device.
How it works
Pick an image and a target format. The page decodes pixels in this tab, draws them on a canvas, then calls the browser encoder (toBlob). For JPEG it can fill a solid background first so transparency does not become an unpredictable color. Output MIME is checked so a silent fallback is not treated as success.
Rules you should expect
Formats are not just MIME labels — transparency, lossy quality, and encode support differ. Use this table of expectations before you pick a target.
- Pipeline: decode → optional JPEG background fill → canvas draw → toBlob(mime, quality). PNG ignores quality (always lossless). WebP at quality 1.0 may switch to lossless mode.
- Transparency: PNG, WebP, and AVIF can keep alpha. JPEG has no alpha — choose white, black, or a custom fill before encode.
- Encode support: decode support ≠ encode support. AVIF encode is mainly Chromium today; some browsers may quietly fall back to another type — we verify blob.type and warn.
- Privacy: your image bytes are not uploaded. Everything runs with built-in browser APIs in this tab.
Example
Input: a 240×160 PNG icon with a transparent background. Target JPEG + white fill → output image/jpeg with no alpha and a white matte. Same icon to WebP at quality 0.85 → often a smaller file at the same pixel size. Use “Load sample” to try both paths.
Good fits
- Web delivery: convert PNG screenshots or photos to WebP/AVIF before uploading to a CMS or CDN.
- Design handoff: flatten a transparent UI icon to JPEG with a chosen background for tools that reject alpha.
- Compatibility: turn an AVIF or WebP download into JPEG for older office or print software.
Frequently asked questions
Does my image leave the browser?
No. Decoding and encoding run locally. You can confirm in DevTools Network that the image file is not POSTed to a server.
Why is AVIF sometimes unavailable?
Many browsers can display AVIF, but only some can encode it (often Chromium). If encode is missing, the option is disabled or conversion fails with a clear message — we do not pretend success.
What happens to transparent pixels in JPEG?
JPEG has no alpha channel. Pick a white, black, or custom background so the result is predictable instead of browser-dependent black or white fill.
Does the quality slider affect PNG?
No. PNG output is lossless and the quality control is ignored. For JPEG, WebP, and AVIF, quality maps to the encoder’s lossy setting (WebP at 1.0 may be lossless).
How do I know the file really became WebP or AVIF?
After convert, check the output stats line for the MIME type, and download the file. If the browser silently fell back, we show an error instead of a fake success.
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Questions or feedback
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