MIME Type & File Signature Checker
Check and detect MIME types of files online. Identify file content types, validate MIME types, and inspect file signatures for web development
Common MIME Types
MIME Type Checker FAQ and Usage Guide
What is a MIME type?
MIME (Multipurpose Internet Mail Extensions) type is a standard way of indicating the format of a file. Web servers use MIME types to tell browsers how to handle files.
Format: type/subtype (e.g., image/png, application/pdf)
What is a file signature (magic number)?
A file signature is a unique byte pattern at the beginning of a file used to identify its format. Unlike file extensions, it's based on the actual file content, making it more reliable.
Examples:
- PNG:
89 50 4E 47 - PDF:
25 50 44 46("%PDF") - JPEG:
FF D8 FF
How to use this tool?
You can use it in two ways:
- Search: Enter a file extension or MIME type to look up information
- File Upload: Upload a file to analyze its actual file signature and determine its MIME type
Why might file extension and MIME type differ?
File extensions can be changed arbitrarily by users, but file signatures are based on the actual file content. For example, a file with .jpg extension might actually be a PNG image.
This tool reads the first bytes of the file to verify its actual format.
What is Content-Type?
Content-Type is the MIME type used in HTTP headers. Web servers use it to tell browsers the format of the data being sent.
Example: Content-Type: image/png
Is my data safe?
Yes! All analysis happens only in your browser. Only the first 16 bytes of uploaded files are read, and files are never sent to any server or stored anywhere.