How to Inspect File Headers and Metadata Online
Understanding file structure and metadata is essential for debugging, security analysis, and file validation. File inspectors reveal hidden information like MIME types, file signatures (magic numbers), and header bytes that identify the true file type. This guide shows you how to inspect file metadata online using fixie.tools — a free tool that runs entirely in your browser for security.
Step 1: Open the File Inspector
Go to fixie.tools/file-inspector. No signup needed. All inspection happens in your browser.
Step 2: Upload a File
Click upload or drag and drop any file type. The tool accepts all file formats and works with images, documents, archives, executables, and more. Your file never leaves your device.
Step 3: Review Basic Metadata
View the file's name, size (in bytes and human-readable format), MIME type, extension, and last modified date. This helps verify file type and detect misnamed files.
Step 4: Examine File Header Bytes
View the first bytes of the file in hex and ASCII format. File headers (magic numbers) identify true file type regardless of extension — PNG starts with 89 50 4E 47, JPEG with FF D8 FF.