🧬 File Type Detector
Find the real type of any file by reading its magic bytes — even when the extension is wrong or missing.
🔐 Files are read locally with the File API and only the first bytes are inspected. Nothing is uploaded to 0Appz or any third party.
How to use this tool
Overview
File Type Detector - Identify File Format by Content reveals what a file really is by reading its magic bytes — the first few bytes that every format uses as a signature. Drop one or many files and get the detected type, real MIME type, suggested extension, file size and a hex preview of the header, plus a match badge that tells you when the extension and the content disagree. That mismatch check is the most useful part: a file named photo.jpg that is actually a PNG, or an .exe disguised as a .pdf, is caught instantly. Everything is read locally through the File API — only the first 32 bytes are inspected, nothing is uploaded, and the tool keeps working offline after loading.Frequently asked questions
How does file type detection work? +
The File Type Detector - Identify File Format by Content reads the first bytes of the file — the magic number or file signature — and compares them against a table of known formats. This is the same method used by the file command and by browsers, and unlike extensions it cannot lie.
Why does my .jpg show as a PNG? +
That means the file content is a real PNG image but someone renamed it with a .jpg extension. This is common after downloads, exports and manual renaming. The tool flags it as a mismatch so you can rename the file correctly.
Why is my Office document shown as ZIP? +
Modern Office files (docx, xlsx, pptx) are actually ZIP containers with XML inside. The signature is identical to a ZIP archive, so the tool reports ZIP or Office file — open it with a ZIP tool to see the internals.
Are my files uploaded anywhere? +
No. Only the first 32 bytes are read locally via the File API. The content never leaves your browser.