JNG Converter
FileFlip converts JNG files into 61 other formats entirely inside your browser, using ImageMagick, MuPDF and Pandoc compiled to WebAssembly. The JNG file is never uploaded to a server: it is read off your disk, converted on your own machine, and saved back by the browser. There is no file-size limit and no account to create.
How do I convert a JNG file?#
- Drop your JNG file onto the converter at the top of this page, or click it to pick one from your computer.
- Choose the format you want out of it. FileFlip downloads the engine that conversion needs, once, and your browser caches it.
- Conversion starts the moment you pick the format, and the result is yours to download. The work happens in this tab, so nothing is uploaded and nothing is queued.
Is it safe to convert JNG files online?#
Yes, because nothing is uploaded. FileFlip converts JNG files inside the browser tab you already have open, using WebAssembly builds of the same engines a desktop converter would install. Your file is read from your own disk into the page's memory, and no request carrying it is ever made.
You do not have to take that on trust. Open your browser's network panel, run a conversion, and you will see the engine come down and your file go nowhere. There is no upload, no server-side copy, no retention window, and no account tied to what you converted.
How FileFlip works lists every engine, its version and its download size, and shows how to check for yourself that nothing leaves your machine.
What happens to a JNG file#
FileFlip converts JNG into 61 formats with ImageMagick, MuPDF and Pandoc, all of it inside the browser tab. Each conversion below names the engine it uses, what it downloads, and exactly what that conversion keeps or drops.
| Category | Image Files |
|---|---|
| File extension | .jng |
| FileFlip support | Read and written |
| Conversions available | 61 |
| Engines | ImageMagick, MuPDF and Pandoc |
| Downloaded to your browser | 14.1 MB on the first conversion, then cached |
What is a JNG file?#
A JNG file holds a single still image whose colour data is compressed as baseline or progressive JPEG inside the same chunk-based container PNG uses, with an optional PNG- or JPEG-encoded alpha channel for transparency.
There's little reason to create a new JNG file today; the format only makes sense inside an existing MNG animation that already mixes JPEG and PNG frames.
Convert JNG to JPG or PNG for anything meant to display in a browser, since none of the major browsers render JNG natively.
The JNG file format reference covers the specification, the programs that open one, and what each conversion keeps or drops.
JNG questions people ask#
What opens a JNG file?
JNG files open in GIMP, Gwenview and ImageMagick-based tools, but no mainstream web browser renders them. That gap is the main reason JNG never spread beyond the small set of software built around the MNG format.
Is JNG the same thing as PNG?
No. A JNG file reuses PNG's chunk-based container but compresses its colour data as JPEG instead of PNG's lossless method, so it behaves more like a JPEG with an optional transparency layer than a true PNG. JNG exists specifically as the lossy, photographic sibling inside the MNG animation format.
Why did JNG never catch on?
JNG's fate was tied to MNG, the animated format it was built to complement, and MNG never got the browser support GIF and later APNG had. Combined with newer formats like WebP and JPEG XL covering the same lossy-plus-transparency need, JNG stayed a niche format used mainly by MNG-aware software.