File Type Detector
Look inside an unknown or misleadingly named file and compare structural evidence with its current extension.
Add a file
Inspect the file signature, container structure, and text content locally.
Any file type · one file at a time
Only the small portions needed for detection are read locally. Your file is never uploaded, renamed, or modified.
How to use File Type Detector
- 1
Choose or drop one file of any type. Detection starts automatically and normally reads only the small portions required for identification.
- 2
Review Detected file type, MIME, Confidence and the File signature / magic bytes that support the result.
- 3
Compare Current extension with Expected/common extension and read the explicit match, mismatch, missing or unverifiable status.
- 4
Use Replace file to inspect another item. The detector reports evidence only and does not rename, convert or repair the source.
Frequently asked questions
About File Type Detector
A filename is a label, not proof of format. File Type Detector examines evidence stored inside a local file and reports whether its current extension agrees. Recognized signatures cover common images, documents, archives, compressed streams, media containers, executables, databases and web fonts, with the supporting bytes kept visible for inspection.
Some formats require more than their opening signature. Office Open XML, EPUB, OpenDocument, APK and JAR are all ZIP-based, so their central-directory names or package mimetype must be inspected before a specific result is justified. ISO Base Media and EBML markers similarly help distinguish common media containers without overstating codec knowledge.
If binary checks do not resolve the file, strict UTF-8 decoding and cautious structural rules can identify JSON, XML, HTML, CSV, Markdown, YAML or general text. Ambiguous content remains Unknown rather than receiving a confident-looking guess. Detection uses bounded local reads and never renames, repairs, converts or uploads the selection.