How does file type detection work?

The tool reads the first few bytes of the file (the header) and compares them against a database of known magic number signatures. Each file format has a unique signature at the beginning of the file. This method is far more reliable than checking the file extension, which can be easily changed.

Can the tool detect all file types?

The tool supports hundreds of common file formats including images, documents, archives, audio, video, and executable formats. Some less common or proprietary formats may not be in the signature database. In such cases, the tool will display the raw header bytes for manual analysis.

Is my file uploaded to a server for detection?

No, the tool only reads the first few bytes of your file locally in the browser using the File API. Your file is never uploaded to any server. This is especially important when analyzing potentially suspicious files, as you can safely check them without any risk of exposure.

What does it mean when the extension doesn't match the detected type?

A mismatch between the file extension and the detected format means the file has been renamed or its extension was changed. This can be intentional (e.g., changing a .txt to .csv for compatibility) or malicious (e.g., renaming .exe to .pdf). Always treat mismatched files with caution.

Can this tool detect malware?

The tool can detect when a file's extension doesn't match its actual format, which is a common malware technique. However, it cannot determine whether a file contains malicious code. For comprehensive malware detection, use a dedicated antivirus solution. The tool is a first-line check for extension verification.

What is a magic number or file signature?

A magic number is a sequence of bytes at the beginning of a file that uniquely identifies its format. For example, PDF files start with the bytes 25 50 44 46 (which spell %PDF), and PNG files begin with 89 50 4E 47 0D 0A 1A 0A. These signatures are defined by the file format specifications.

How much of the file does the tool read?

The tool typically reads only the first 4 to 16 bytes of the file, which is sufficient for most magic number detections. Some formats require reading slightly more bytes for accurate identification. The tool never reads the entire file content, ensuring fast detection and minimal data access.

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File Type Detector

A file type detector is an online tool that identifies the true format of any file by reading its magic number signature, not the extension. Upload a file and instantly see its real format, MIME type, and whether the extension matches the detected type.

100% FreeNo Signup RequiredBrowser-BasedPrivate & Secure

What is File Type Detector?

A file type detector is an online utility that identifies the true format of a file by reading its internal signature bytes (magic numbers), rather than relying on the file extension, which can be misleading or deliberately changed.

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These tools work great alongside File Type Detector:

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Start Using File Type Detector Today

Relying on file extensions alone is a security risk — our file type detector reveals the true format of any file by analyzing its binary signature. By reading only the essential header bytes, it identifies files accurately while keeping your data completely private. Verify your files today and ensure you always know what you're really dealing with.

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