About FormatYeti
FormatYeti is a small collection of free file converters with one rule: your files never leave your device. Every conversion runs inside your web browser, on your own computer or phone.
Why we built it
Converting a WebP to a PNG or a few photos to a PDF should not mean uploading private pictures and documents to an unknown server, waiting in a queue and hoping they are deleted afterwards. Modern browsers can decode images, run compiled code and build PDF files on their own, so for everyday conversions an upload is simply unnecessary.
How it works
When you open a converter, your browser downloads the page and the small program that does the conversion. When you choose a file, it is read directly from your device into the browser’s memory, converted there, and offered back to you as a download. At no point is the file sent over the internet. You can check this yourself: load a converter, switch off your Wi-Fi, and convert an image.
Because your own device does the work, speed depends on its power and memory. Images take a moment; very large PDFs on an older phone take longer.
What we use
- Your browser’s built-in image decoders and the HTML canvas for reading and writing WebP, PNG, JPG, AVIF and SVG.
- Google’s libwebp (BSD License) through jSquash(Apache License 2.0) for saving WebP in browsers that cannot do it themselves.
- pdf.js by Mozilla (Apache License 2.0) for reading PDF files.
- libheif (LGPL 3.0) throughlibheif-js for reading HEIC photos in browsers without built-in support. Its unmodified licence text is at/vendor/libheif/LICENSE.
- UTIF.js by Photopea (MIT License) for reading TIFF files.
- pdf-lib (MIT License) for creating PDF files.
- fflate (MIT License) for ZIP downloads.
What is next
FormatYeti currently offers 27 converters for images and PDFs. Audio and video converters, such as MP4 to MP3, are coming next, followed by more image and PDF tools. If you need a converter we do not have yet, pleaselet us know.