Don't upload your files to the cloud. Convert them on your own computer, in a flash.

And it has a cat.

Shrinking a picture or turning JSON into YAML shouldn't mean uploading your file to a site you don't know. Catail Convert converts images, documents, data files and archives on your own computer, with every processor core. It doesn't even need an internet connection.

Download for WindowsLatest release What does it convert?

Catail Convert

PNGholiday.png4.2 MB JSONdata.json18 KB MDnotes.md6 KB

JPGWEBPPDF Nothing goes to a server

WEBPholiday.webp4.2 MB → 680 KB −84% YAMLdata.yaml15 KB PDFnotes.pdf48 KB

Formats

Drag, drop, pick.

It looks at what each file is and offers only the targets that make sense. Drop a mix and it sorts them into groups.

Images

PNG · JPG · WEBP · AVIF · SVG · ICO · BMP · TIFF

A quality slider, resizing that keeps the aspect ratio, multi-size ICO, and EXIF/GPS removal. Before and after sizes side by side.

Documents

MD · TXT · HTML · PDF

Combine images into one PDF, merge PDFs or split them by page range. Markdown to HTML, and to PDF with proper accented letters.

Data files

JSON · CSV · YAML · TOML · XML

Each into any other, and into a Markdown table. Minify or pretty-print JSON, pick the CSV delimiter. Output is always UTF-8.

Audio and video

MP4 · MKV · MOV · WEBM · MP3 · WAV · FLAC · OGG

With FFmpeg: pull the audio out of a video, lower the resolution, make a palette-optimized GIF. FFmpeg isn't bundled; it asks first.

Optional

In bulk, and fast

Hundreds of files at once, on every core. A broken file only fails its own row; the rest carry on.

How to use

Three ways in.

The cat box

Opens in a corner of the screen from the tray or with Alt+C. Drop files on the cat, pick a format from the bubbles, done.

The studio window

For many files: a target and a size comparison on every row (4.2 MB → 680 KB), quality, the output folder and a progress bar.

From the clipboard

A picture or some JSON on the clipboard? Ctrl+V in the app adds it without picking a file. Copy the result back with one click.

Together with Catail-SS

Two cats, one team.

With Catail-SS installed too, the two find each other and offer extra options. Either one still works on its own.

Convert a screenshot

Select an area in Catail-SS and its toolbar shows Convert: the picture drops straight into the cat box; pick a format, done.

Add results to the queue

Converted files join Catail-SS's queue with one click; Ctrl+V in the target app pastes them all in order. Or let it happen on its own.

Convert the queue

When Catail-SS's queue holds something, Convert tells you and takes it all in with one click. Catail-SS's queue panel can send it over too.

They wear the same cat and speak the same language: change the cat in Catail-SS and Convert follows. All on your computer; nothing between them goes online. Needs Catail-SS 0.9.8 or later.

Privacy

Your files never leave your computer.

Online converters upload your file to their servers first. Catail Convert does everything on your own processor; no telemetry, no account.

Converting is fully offline
No telemetry, no ads, no account
It goes online in one case only: if you agree to download FFmpeg for audio and video
FFmpeg is the official static build (about 110 MB), checked against its SHA-256

The full privacy notice

What it can't do yet

PDF pages to images: that needs a full PDF renderer (pdfium or MuPDF, C/C++). It can't be done offline in pure Rust, so it isn't included.
HTML to PDF carries the text only; layout and CSS don't come along.
Windows 10 and 11 only, for now.

Open source

The code is out in the open.

All of Catail Convert's code is on GitHub. Built with Tauri 2: the converters are Rust (image, lopdf, rayon), the interface React and TypeScript. Catail's cats and themes come along.

License: MIT. Free to use, change and share.

Catail-Studio/catail-convert

# Needs Node.js 20+, Rust and Windows 10/11
git clone https://github.com/Catail-Studio/catail-convert
cd catail-convert
npm install
npm run tauri dev