If you’ve ever had to change a file from one format to another, you probably know the drill: type “convert [file type] to [file type]” into Google, click the first sketchy-looking site, and hope it doesn’t spam you with pop-ups. Sometimes it works; sometimes it doesn’t. And then there are the annoying roadblocks, such as your file being too big, or the site wants your email before it’ll even touch the file. To make matters worse, the FBI recently dropped a pretty stark warning about these free conversion sites, pointing out that some of them can sneak in malware or quietly siphon off your data.
That’s just how it’s been for years, and it was never a great experience. Then I came across VERT.sh, and it feels like I finally found the converter I’ve been wishing for. It’s open source, fast, private, and works right in your browser without any sketchy middlemen.
Meet VERT.sh
A lightweight file converter in your browser
The vert.sh interface is clean and straightforward. To the right is a large drop zone where you can drag in a file from your desktop or click to browse your folders. Once you upload a file — whether it’s an image, audio clip, document, or video — you simply choose the output format from a drop-down menu and hit the convert button. Smaller files process almost instantly, while larger ones take a bit longer.
Videos work slightly differently. Although the upload experience is the same, the conversion itself happens on a hosted service rather than in your browser. That means your video leaves your device temporarily, and the processing time depends on your upload speed and the server workload. According to the site’s About page, videos are automatically deleted either after you download them or within an hour of upload, whichever comes first.
Handling multiple files is just as seamless. You can drop in several at once, convert them together, and then download everything in one go as a ZIP archive. The only limitation is that bulk format settings apply best when the files are all of the same type — for example, all images or all audio. If you’re mixing file types, you’ll still be able to process them, but you’ll need to choose output formats separately for each group.
How VERT pulls it off without the cloud
WebAssembly (WASM) is the sauce
Typically, converting a file from one format to another means either installing heavy desktop software or uploading it to an external server. VERT takes a different approach by using WebAssembly (WASM), which allows powerful conversion tools to run directly in your browser.
Digging into its GitHub documentation, I found that VERT relies on well-established libraries like FFmpeg for media, libvips for images, and Pandoc for documents. Since many of these are available in WASM, conversions for images, audio, and documents can be handled locally on your device without requiring an external server.
Again, the main exception is video. On VERT’s public site, video conversions are offloaded to a server because the process is still resource-intensive. However, if you’d rather keep everything local, you have the option to self-host the backend and manage video processing yourself (which I’ll explain shortly).
You can self-host VERT to handle video conversion locally
You don’t have to rely on external servers
VERT also comes with a companion tool called vertd, a daemon that runs on your own computer or server. With it, your browser connects directly to vertd, and all video processing takes place on your own hardware rather than a third-party server.
Getting started usually means downloading the daemon, running it (often through Docker), and pointing the VERT web interface to its location. It’s a bit more technical than simply dragging and dropping files on the public site, but once it’s set up, you essentially have your own private conversion service. If you need the details, the VERT team provides a step-by-step guide on GitHub.
VERT is probably the best way to convert files without the internet
VERT isn’t the only way to handle file conversions, but it’s definitely the most refreshing I’ve tried in a while. You could stick with old-school desktop apps like HandBrake, Calibre, or even Adobe’s ecosystem if you’re deep in it. They’re good for the task, no doubt, but they can feel heavy and bloated for quick jobs. On the flip side, there are plenty of online converters that are dead simple to use, but they come with the baggage of slow uploads, privacy worries, and the occasional sketchy ad trap.
VERT hits a sweet spot I didn’t know I was missing. It gives me the convenience of a web tool without the feeling that my files are being siphoned off to some random server, and it does it all with a clean interface that actually makes the task enjoyable. For me, that balance of ease, privacy, and speed is what finally makes file conversion feel, well, easy.
