File Type Detector by Magic Bytes

Magic bytes (or file signatures) are short sequences of bytes at the beginning of a file that uniquely identify its format. Operating systems and software use them to determine how to handle a file, regardless of its extension. For example, a PNG image always starts with 89 50 4E 47 in hexadecimal.

This tool reads the first few bytes of your selected file directly in your browser (using the FileReader API) and compares them against a built‑in database of known magic byte patterns. No file data is ever uploaded to a server, ensuring complete privacy.

Yes, a file can be deliberately given a wrong extension or its magic bytes can be tampered with. Also, some plain text files or formats (like CSV) don't have a standard magic number. In such cases, this tool may return "Unknown". Detection is based purely on the binary signature, so it's not 100% foolproof for all file types.

The database includes over 30 common file types, among them: images (JPEG, PNG, GIF, BMP, TIFF, WebP), documents (PDF, DOCX, XLSX, PPTX, ODT), archives (ZIP, GZIP, RAR, 7z), audio (MP3, WAV, FLAC, OGG), video (MP4, AVI, MKV), and many more. We regularly update the signature list.

This can happen if the file format is not in our database, the first bytes don't match any known signature, or the file is a plain text/CSV/JSON file that lacks a binary magic number. Also, very small files (< 4 bytes) might not have enough data to detect.

Absolutely. The entire process runs client‑side in your browser. The file is never transmitted to any server. You can even disconnect your internet after loading the page and the tool will work offline.