File Signature Database
Look up file magic bytes and hex signatures for any format with our free interactive reference. Covers over 100 signatures across images, audio, video, documents, archives, executables, fonts, disk images, databases, 3D models, and more - with hex bytes, ASCII interpretation, offsets, MIME types, and format descriptions. Search by extension, name, or hex pattern. No signup required.
Browse 147 file signatures (magic bytes) used to identify file types. Search by extension, name, hex signature, or ASCII text. Click any entry for full details.
Why Use Our File Signature Database?
Comprehensive File Signature Database
Browse over 100 file signatures (magic bytes) across all major file categories - images, audio, video, documents, archives, executables, fonts, disk images, databases, 3D models, and more. Our file signature database covers every common file format you encounter.
Instant Search & Filter
Search by file extension, format name, hex signature, ASCII text, or MIME type to find any file signature instantly. Filter by category to focus on specific file types. All filtering runs in real-time as you type - no page reload needed.
File Signature Reference Online - No Installation
Use our file signature database directly in any browser with no downloads, plugins, or app installs required. Look up any magic byte sequence from any device, anywhere, instantly.
100% Free Forever
Our file signature database is completely free with no signup, no ads, and no usage limits. Look up file signatures as many times as you need - completely free, forever.
Common Use Cases for File Signature Database
Digital Forensics & File Recovery
Identify unknown file types by their magic bytes during forensic investigations. Use our file signature database to determine the true format of recovered files, even when extensions are missing or corrupted.
File Type Verification
Verify that a file's extension matches its actual content by comparing the magic bytes against our file signature database. Detect files with incorrect extensions, whether from accidental renaming or deliberate obfuscation.
Security & Malware Analysis
Examine file headers to detect potentially malicious files disguised as safe types. Our file signature database helps security researchers identify files whose magic bytes don't match their declared extensions.
Software & Library Development
Implement file type detection in your own applications using the magic byte sequences from our file signature database. Reference byte offsets and hex patterns for writing binary file parsers and validators.
Data Recovery & Backup Validation
Identify file types in raw disk images, backups, or memory dumps by scanning for known magic byte patterns. Use our file signature database to recognize file headers during data recovery operations.
Learning & Education
Learn how computers identify file types at the binary level. Our file signature database is an invaluable resource for computer science students, cybersecurity learners, and anyone interested in file format forensics.
Understanding File Signatures (Magic Bytes)
What Are File Signatures (Magic Bytes)?
File signatures, also known as magic bytes or magic numbers, are unique byte sequences at the beginning of a file that identify its format. Every file format has a distinctive signature that allows operating systems, applications, and forensic tools to recognize the file type without relying on the file extension. For example, JPEG images start with FF D8 FF (hex), PDF documents start with 25 50 44 46 (which reads "%PDF" in ASCII), and PNG images begin with 89 50 4E 47. These signatures are defined in file format specifications and registered with the IANA. Our file signature database catalogs over 100 of the most common signatures across all file categories.
How to Use This File Signature Database
- 1. Search by Extension or Name: Type a file extension (e.g. "pdf"), format name (e.g. "JPEG"), or hex pattern (e.g. "FF D8") in the search box to instantly filter signatures. All filtering runs locally in your browser.
- 2. Filter by Category: Use the category dropdown to focus on a specific group of file types - images, audio, video, documents, archives, executables, fonts, disk images, databases, 3D models, and more.
- 3. Expand for Full Details: Click any signature row to expand it and see the full hex signature, ASCII interpretation, byte offset, MIME type, and a detailed description of the format.
How File Signatures Are Used
- Operating System Detection: macOS, Linux, and Windows all use magic byte detection (via the
filecommand or equivalent) to determine file types for the correct application association. - Digital Forensics: Forensic tools scan drives for known magic byte patterns to recover files that have had their extensions removed or filesystems corrupted. File carving relies entirely on header and footer signatures.
- Security Scanning: Email gateways, web application firewalls, and antivirus software check magic bytes to verify that uploaded files are what they claim to be, preventing attackers from disguising executables as innocent image or document files.
- Web Browsers: Browsers use MIME sniffing - looking at the first bytes of a response - to determine content type when the Content-Type header is missing or misleading.
File Signature Limitations & Considerations
While file signatures are reliable for identifying file types, there are important caveats to know. Some formats share the same header (all OOXML documents - DOCX, XLSX, PPTX - start with ZIP header 50 4B 03 04). Container formats like ZIP and RIFF require inspecting internal structures for precise identification. Files can also have false headers if specifically crafted to deceive. For forensic certainty, combine magic byte analysis with metadata examination, file structure validation, and content analysis. Our file signature database provides the magic byte data, but always verify with additional tools for critical security decisions. All processing in this file signature database is local - no files are uploaded or sent anywhere.
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Frequently Asked Questions About File Signature Database
What is a file signature (magic bytes)?
A file signature, also known as magic bytes or magic number, is a unique sequence of bytes at the beginning of a file that identifies its format. Operating systems and applications use these signatures to determine file types regardless of the file extension. For example, all JPEG images start with the bytes FF D8 FF in hexadecimal.
How do I use this file signature database?
Use the search box to look up file signatures by extension (e.g., "pdf"), format name (e.g., "JPEG"), hex pattern (e.g., "FF D8"), or ASCII text (e.g., "%PDF"). You can also filter by category using the dropdown. Click any entry to expand it and see the full details including hex signature, ASCII interpretation, byte offset, MIME type, and format description.
Why should I use magic bytes instead of file extensions?
File extensions can be easily changed or faked, but magic bytes reveal the true content type of a file. For security analysis, digital forensics, and data recovery, relying on magic bytes is essential because they cannot be easily disguised without specialized knowledge. Our file signature database helps you identify the real format behind any extension.
Is this file signature reference database free to use?
Yes! Our file signature database is 100% free with no signup, no ads, and no usage limits. Look up file signatures as many times as you need - completely free, forever. All search and filtering happens locally in your browser with no data sent to any server.
How are file signatures determined by the operating system?
On Unix-like systems (Linux, macOS), the file command reads the magic bytes and consults a magic database (/usr/share/misc/magic or similar). Windows uses a similar mechanism through the IDataObject interface and registered file type handlers. Browsers use MIME sniffing algorithms to read file headers when the Content-Type header is missing.
What is the difference between magic bytes and file extensions?
A file extension (like .pdf or .jpg) is just a label in the filename that tells the operating system which application to use. Magic bytes are the actual binary data at the start of a file that definitively identify its format. While extensions can be changed by anyone, magic bytes require specialized tools and knowledge to alter without corrupting the file.
Can two different file formats have the same magic bytes?
Yes. For example, all Office Open XML formats (DOCX, XLSX, PPTX) share the same ZIP header (50 4B 03 04). Similarly, the OLE2 Compound Document format (D0 CF 11 E0) is used by DOC, XLS, PPT, MSG, and other legacy Office formats. For precise identification of these formats, you need to examine internal file structures beyond the initial magic bytes.
How accurate is magic byte file type detection?
Magic byte detection is highly reliable for common file formats, especially when checking the first 4-8 bytes. However, it is not 100% foolproof. Corrupted files may have valid headers but damaged content. Deliberately crafted files can include valid headers of one format while containing content of another. For maximum accuracy, combine magic byte analysis with file structure validation and metadata inspection.
Are my searches private when using this file signature database?
Absolutely. Our file signature database is a fully client-side reference tool. The file signature data is embedded in the page itself, and all search and filtering operations run locally in your browser. No search queries are sent to any server, and no files are uploaded. Your lookups remain completely private.