Stackbench Image Format Converter
Re-encode your images between PNG, JPG, WebP and AVIF at their original dimensions, flattening transparency when a JPG needs it, entirely on your device — nothing is uploaded.
JPG has no alpha channel, so transparent areas are flattened onto the surface colour below — that colour comes from the active theme.
Flatten onto
PNG is lossless, so quality is ignored. A photo saved as PNG normally grows.
No images loaded yet. Files stay on this device while they are converted.
How to use
- Drop images on the drop zone, or press Choose images to add several files at once.
- Open Target format and pick PNG, JPG, WebP or AVIF; formats this browser cannot encode are disabled and named in the status line.
- Set Quality for a lossy target, then press Convert images — the dimensions stay exactly as they were.
- Press Download on a row or Download all for the set, and compare source size → converted size to see whether the swap actually paid off.
Frequently asked questions
Are my images uploaded to be converted?
No. Each conversion runs through a canvas inside your browser, so the file bytes never leave the page — which is what makes it safe for ID scans, screenshots and unreleased artwork.
Does converting lose quality?
Converting to PNG is lossless. Any lossy target (JPG, WebP, AVIF) re-compresses from the already-decoded pixels, so a little detail is lost per generation: keep quality around 85–90 and avoid hopping between lossy formats repeatedly. At the same visible quality WebP and AVIF usually come out clearly smaller.
Which formats can I convert to, and what happens to transparency?
PNG and JPG are available in every browser; WebP depends on your engine, and AVIF only appears when the browser really returns an AVIF blob (it stays hidden in the disabled state otherwise). JPG has no alpha channel, so transparent areas are first flattened onto the surface colour of the active theme, shown next to the format list.
Related tools
Image Compressor & Resizer
Shrink JPG, PNG and WebP files by adjusting quality and maximum width. Processing stays on your computer, so private images never leave it.
Image Resizer
Resize one or more images to exact pixels or a percentage, with the aspect ratio locked and no surprise re-compression. Runs on your device, no upload.
Photo Metadata Viewer & EXIF Checker
Read the EXIF inside a photo: camera, lens, exposure, date and GPS coordinates. Strip that metadata and download a clean copy. Runs offline, no upload.