Convert JPG to PNG
Convert JPG to PNG online, free and 100% in your browser. No upload, no signup, no size limit — WebAssembly does the work on your device.
How to convert an image
- Drop or pick your JPG file — or paste it with Ctrl/⌘+V.
- PNG is already selected — output is lossless, optimized with oxipng.
- Convert, compare the before/after, and download — all on your device.
Why convert to this format?
JPEG is the universal lossy photo format — small and readable everywhere, but with no transparency. PNG is a lossless format with an alpha channel — pixel-perfect for logos, screenshots and line art.
OptImg runs the same Rust codecs desktop tools use, compiled to WebAssembly, so you get desktop-grade PNG output at a sensible default (lossless output) — adjustable at any time — without ever uploading your image.
Everything happens locally: your JPG is decoded, re-encoded to PNG and handed straight back as a download. No server sees a single byte, which is why there's no queue and no file-size cap.
Frequently asked questions
- Is my JPG uploaded to a server?
- No. The JPG-to-PNG conversion runs entirely in your browser with WebAssembly — your file never leaves your device, there is no queue, and no size limit beyond your device's memory.
- Will converting to PNG change the image?
- PNG output is lossless, so every pixel the decoder reads is preserved exactly — and the file is optimized with oxipng for the smallest lossless size. A “smaller file” toggle can quantize to a palette when you want extra savings.
- Is the JPG to PNG converter free?
- Yes — completely free, with no signup, no watermark and no cap on how many files you convert. There is nothing to install; it runs in your browser.