Free online file converters can be tracking machines (a Reddit audit + safer options)

What got my attention

A post on r/YouShouldKnow went viral after claiming that a popular “free” file converter session triggered hundreds of cookies across hundreds of third-party domains.

Whether or not the exact numbers change over time, the broader point is worth understanding: on many free converter sites, the conversion tool is the feature you came for, but the tracking stack is part of the business model.

Source: Reddit thread

What the comments revealed

The top comment pointed out something important: you don’t need to accept this tradeoff.

There are open-source and local-first converters that run entirely on your device.

That’s the real takeaway. If a tool can run locally, it can be just as convenient without turning your conversion session into an ad-tech party.

The bigger risk is still the upload

Many converters process files server-side.

That means your resume, bank statement, contract, or ID scan leaves your device and lands on infrastructure you don’t control.

Think of it like handing paperwork to a copy shop.

You might get the job done, but you’ve also created a new place where your document exists.

A safer default: convert locally

If the file is sensitive, the safest default is local conversion.

You have three realistic options:

• Use a local browser converter (WebAssembly/WASM) so the conversion runs in your tab.
• Use a desktop app that converts locally on your computer.
• Use command-line tools like FFmpeg/ImageMagick/LibreOffice if you’re comfortable.

The simple option (no command line)

How to Convert has two ways to convert locally:

Free browser converter: runs common multimedia conversions locally in your browser using WASM. No upload.

Paid desktop app: supports many more formats and conversions, using the same kinds of local engines that online sites run on their servers, but privately on your computer.

Both are drag and drop.