File MIME Type Checker
Safely determine a file's true MIME type (Media Type) based on its binary content signatures, processed securely in your browser.
Analyzing...
Reading file signatures locally...
Select your file below for instant analysis. No files are uploaded to our servers.
Drag & Drop Your File Here
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What is a MIME Type?
A MIME (Multipurpose Internet Mail Extensions) type, also known as a Media Type or Content Type, is a standard identifier used to indicate the nature, format, and content of a file or assortment of bytes.
Web servers heavily rely on MIME types within the Content-Type HTTP header to instruct web browsers on exactly how to handle the file being sent (for example, whether to display an image natively, render raw HTML, or trigger a file download dialog).
Common MIME type examples include text/html, image/jpeg, application/pdf, audio/mpeg, and application/octet-stream (which is used as a fallback for generic binary data).
Our checker analyzes the file's actual binary content (often referred to as "magic numbers" or file signatures) to determine the true MIME type, providing a much more reliable result than simply trusting the text of the file extension.
How To Check a File's Content Type
Select the File
Drag and drop the file you want to investigate into the upload box or click to browse your device's file system.
Client-Side Analysis
Your web browser reads the file's internal "magic numbers" securely without ever uploading the file to an external server.
View the MIME Type
Instantly receive the exact, formatted string (e.g., image/png) representing the actual media type of the file.
Frequently Asked Questions
File extensions (like .jpg, .pdf, or .exe) can easily be renamed, spoofed, or manipulated by malicious actors to appear safe. By checking the internal file signature based on the binary content, you get a significantly more accurate and reliable identification of the true file type.
The application/octet-stream MIME type is the default fallback for generic binary files when a more specific format cannot be identified. When browsers encounter this type, they typically trigger a standard "Save As" download dialogue instead of trying to open or display the file.
Yes, it is 100% secure and private. The Toolszu File MIME Type Checker uses modern HTML5 technology to process the file entirely within your own web browser. Your file is never uploaded, transmitted, or saved to our servers.
"Magic numbers" refer to the first few bytes (the binary signature) embedded inside the actual content of a file. These bytes are unique to specific file formats (e.g., all PDF files start with the hex code for `%PDF-`). By reading these bytes, we can determine the exact MIME type regardless of the file's name.
Unlike images or executables, raw text files (like CSV, JSON, or TXT) rarely have embedded magic numbers or distinct binary headers. If a unique binary signature isn't found, the tool falls back to checking your browser's default mapping for that file type.
No. This tool is strictly a developer utility designed to read file signatures and return the structural MIME type. It does not perform antivirus scanning or execute malware detection. You should always scan suspicious files with dedicated antivirus software.