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Supports batch upload, automatically detects real file type (Magic Number)
Supports batch upload, automatically detects real file type (Magic Number)
File Type Detector is a powerful pure frontend tool that accurately identifies the real file format by reading binary file header signatures (Magic Number). Unlike tools that rely only on file extensions or browser MIME types, our tool directly analyzes the binary content of files to ensure accurate identification results. All detection processes are completed in your browser without uploading any files to servers, fully protecting your privacy and data security.
| File Type | Hex Signature | Extension |
|---|---|---|
| 25 50 44 46 | ||
| PNG | 89 50 4E 47 0D 0A 1A 0A | .png |
| GIF | 47 49 46 38 (GIF8) | .gif |
| JPEG | FF D8 FF | .jpg |
| WebP | 52 49 46 46 ... 57 45 42 50 | .webp |
| ZIP | 50 4B 03 04 | .zip |
| GZIP | 1F 8B | .gz |
| 7Z | 37 7A BC AF 27 1C | .7z |
| RAR v5 | 52 61 72 21 1A 07 01 00 | .rar |
| MP3 | 49 44 33 (ID3) / FF FB | .mp3 |
| MP4 | 66 74 79 70 (ftyp) | .mp4 |
| WebM/MKV | 1A 45 DF A3 | .webm |
| BMP | 42 4D (BM) | .bmp |
| TIFF (LE) | 49 49 2A 00 | .tiff |
| TIFF (BE) | 4D 4D 00 2A | .tiff |
| Office | D0 CF 11 E0 A1 B1 1A E1 | .doc/.xls/.ppt |
| EXE | 4D 5A (MZ) | .exe |
| ELF | 7F 45 4C 46 | .elf |
| Java | CA FE BA BE | .class |
| TTF | 00 01 00 00 | .ttf |
| WOFF | 77 4F 46 46 | .woff |
| WOFF2 | 77 4F 46 32 | .woff2 |
| PSD | 38 42 50 53 (8BPS) | .psd |
What is a Magic Number?
A Magic Number is a unique identifier for a file format, usually located in the first few bytes of a file. Each file format has its specific Magic Number used to identify the real format. For example, PNG files always start with 89 50 4E 47 0D 0A 1A 0A. This method is more reliable than relying on file extensions, as extensions can be easily modified or forged.
Why does the browser detection type differ from the signature detection type?
Browsers mainly rely on file extensions and MIME types returned by servers to determine file types. This information can be misconfigured or intentionally spoofed. Signature detection directly reads the binary content of files and can identify the real format. When they differ, the signature detection result is usually more accurate.
Is this tool safe? Will my files be uploaded to a server?
Completely safe. All file detection is done in your browser using the browser's File API and ArrayBuffer. No file content is uploaded to any server. Your file privacy is fully protected.
Which file formats are supported?
Currently supports 40+ file formats, including images (PNG, JPEG, GIF, WebP, BMP, TIFF, SVG, ICO, PSD), audio (MP3, WAV), video (MP4, WebM, AVI, FLV), documents (PDF, DOC, XLS, PPT, DOCX, XLSX, PPTX), archives (ZIP, RAR, 7Z, GZIP, TAR), fonts (TTF, OTF, WOFF, WOFF2), executables (EXE, ELF, Mach-O), and more.
How can I tell if a file is spoofed?
If the file extension doesn't match the Magic Number detection result, it may indicate the file has been renamed or spoofed. For example, a file that's actually an EXE renamed to PDF would show detection type as Windows Executable while the browser type shows application/pdf. This situation requires attention as it could be a malicious file.
Can I detect multiple files at once?
Yes. You can select multiple files at once, and the tool will detect each one and display results for all of them. This is useful for batch verification of file types.