Choose a file to inspect its first 64 KB. Detection is a clue based on limited data, not proof of file validity, safety or complete format support.
Runs locally in your browserSignature detection is a clue, not an antivirus verdict.
MIME & File Signature Detector belongs to the reference tables on KivTools. The workbench above handles the whole job on one screen: files chosen from your device, then a text result you can copy.
The conversion runs inside the page with browser JavaScript. Nothing you enter is uploaded, the tool keeps working offline, and it is safe for data you are not allowed to send to a third party.
Measurement tools are about units and rounding rather than arithmetic: the number is easy, agreeing on what it means is not. These converters use fixed definitions, so the result can be reproduced and audited instead of depending on a rule of thumb.
Errors creep in through mixed systems: a value that is inches in one field and centimetres in another, a date counted in local time, or a conversion applied twice. Write the unit next to the number and convert once.
Browsers, desktop tools and command-line utilities should agree on the result; a mismatch usually means a different encoding, locale or version. Sanity-check the magnitude first — if the order of magnitude looks wrong, the unit mapping is wrong — and only then compare decimals.
Standards bodies, not the tools, define these ratios; where a domain uses a conventional approximation (such as 30-day months) the tool follows the convention and the difference is real. Keep a copy of the input while you experiment, so a wrong setting never destroys the source.
Accepts a local file via picker/drop and returns detected MIME type, extension/browser-MIME comparison, and leading hex bytes for PNG, JPEG, PDF, ZIP, WASM, WOFF, JSON, XML, CSV.
Use it to verify that a file's extension matches its real content before upload, inspect unknown binary signatures, or debug mismatched browser MIME types in web apps.
The selected local file is processed by browser JavaScript only; its bytes are not uploaded to KivTools.
Magic-byte detection is heuristic and cannot guarantee the file is safe, nor does it cover every possible format; treat results as investigative clues, not an antivirus verdict.
Yes. Every tool on KivTools is free, needs no account and has no usage quota. There is no paid tier hiding behind the workbench, and no email address is required to use the result.
Inside your browser. The page loads a script once and the conversion happens on your machine, which is also why the tool still works when the network drops.
Accepts a local file via picker/drop and returns detected MIME type, extension/browser-MIME comparison, and leading hex bytes for PNG, JPEG, PDF, ZIP, WASM, WOFF, JSON, XML, CSV. Large inputs are usually handled without trouble, but extremely large ones are better processed in a local command-line tool.
A reference is only useful if it matches your version: check dates and scope. Compare a small known-good sample first when the output feeds an automated pipeline.
The output is yours: no watermark, no licence tag, no attribution requirement. Check the underlying format or library licence when the result ships in a product.
The page works in any modern mobile browser, and the layout collapses to a single column on small screens. Local tools keep working offline once the page has loaded.