What this site is
FileKit is a catalogue of focused file utilities. Each one does a single job: convert a PNG to a JPG, compress a PDF, minify a stylesheet, turn a spreadsheet export into JSON, check a colour pair against the contrast thresholds. There is no dashboard to learn and no account to create. You land on the page that matches what you searched for, do the thing, and leave.
Why the tools run locally
Modern browsers can decode images, parse documents, hash data and encode media without any help from a server. Almost every online converter ignores that and uploads your file anyway, because a server pipeline is easier to build. The cost is paid by you in upload time, in queue time, in file size caps and in handing a copy of your file to an operator you know nothing about.
Building the other way takes more care but it produces a better tool. There is no upload step, so large files are practical. There is no per user compute cost, so nothing needs metering. And privacy stops being a promise in a policy document and becomes a property of the architecture: the file cannot leak to us because it never reaches us.
How it is paid for
Display advertising, and nothing else. There is no premium tier, no data sale and no newsletter harvesting your address. Because hosting a static site costs close to nothing and the conversions cost nothing at all, advertising alone is enough to keep the whole catalogue free.
Where to start
The explore page lists every tool grouped by category. If you already know what you need, the search box in the header opens with the keyboard shortcut command K and matches on tool name, file format or task.
Accuracy and corrections
Every tool page documents which formats it accepts, what it produces and where browser support is uneven. Where a browser cannot do something natively, the page says so rather than failing halfway through a conversion. If a tool produces a result you believe is wrong, the details on its page will tell you which specification it is following.