About FileMerlin
What this is
FileMerlin is a file converter that does its work inside your browser. When you convert an image here, the file is read from your disk by the page, decoded by the browser image engine, redrawn onto a canvas and encoded again into the format you asked for. All of that happens on your own machine. At no point is the file transmitted anywhere.
That design is unusual. Most online converters upload your file to a server, place it in a queue, convert it there and give you a link to the result. The approach works, but it means handing a stranger a copy of your file and trusting a promise about what happens to it afterwards.
Why it exists
The immediate reason is the WebP problem: the web now serves images in a format that a great deal of desktop software still refuses to open. Solving that should not require uploading a screenshot to an unknown server.
The broader reason is that browsers have quietly become capable of this. Image decoding, canvas rendering and format encoding are standard features now. For a large class of everyday conversions, a server adds latency, cost and risk without adding capability.
How to verify the privacy claim
Do not take our word for it. Open your browser developer tools, switch to the Network tab and convert a file. You will see the page and its assets load, and then nothing further. You can also disconnect from the internet once the page has loaded and convert anyway, which no upload-based converter can do.
Limits, stated honestly
Because your browser does the work, its limits are the limits. Very large images can exhaust available memory, not every browser can encode every format, and animated images convert as a single still frame. Where a limit applies, the tool says so plainly instead of failing silently.
Contact
Questions, bug reports and format requests are welcome at hello@filemerlin.com. Reports that mention the browser you used and what you expected to happen get answered fastest.