File Metadata Viewer View comprehensive file metadata including size, type, entropy, and hex header.

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File Metadata Viewer

View comprehensive file metadata including size, type, entropy, and hex header.

Upload any file

Drop or select any file to inspect.

View metadata

See detailed file properties and size breakdown.

Check entropy

View Shannon entropy to assess file content type.

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What Is File Metadata Viewer?

File Metadata Viewer provides detailed information about any uploaded file. Beyond basic properties like name and size, it shows the file extension, MIME type, last modified date, whether it is text or binary, a complete size breakdown in multiple units, the file header in hexadecimal, and Shannon entropy. Shannon entropy measures the randomness of the file content — high entropy suggests compressed or encrypted data, while low entropy indicates structured text or repeated patterns.

Why Use File Metadata Viewer?

Detailed metadata: name, size, type, extension, last modified.
Shannon entropy calculation to identify compressed/encrypted content.
Size breakdown in bytes, KB, MB, and bits.
File header hex dump for format identification.

Common Use Cases

File Investigation

Investigate unknown files by examining their metadata, hex header, and entropy.

Security Analysis

Check file entropy to identify potentially encrypted or packed malware.

Development

Verify file properties during application development and testing.

Data Classification

Classify files as text or binary based on MIME type and entropy analysis.

Technical Guide

The viewer collects metadata from two sources: the File API (name, size, type, lastModified) and byte-level analysis of the first 8KB.

Shannon entropy is calculated using the formula: H = -sum(p(x) * log2(p(x))) for each byte value x. A byte frequency histogram is built from the sample, and the probability of each byte value is used to calculate entropy in bits per byte. Maximum entropy is 8 bits/byte (perfectly random). Text files typically have 3-5 bits/byte, compressed files 7-8 bits/byte.

File category (text vs binary) is determined by MIME type and file extension. Common text MIME types and extensions are checked.

The hex header shows the first 32 bytes in hexadecimal format, useful for identifying file formats by magic bytes.

Tips & Best Practices

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High entropy (>7.5) suggests compressed or encrypted content.
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Low entropy (<4) indicates repetitive or structured text.
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The hex header can help identify the file format when the extension is missing.
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Only the first 8KB is read — analysis is fast even for very large files.

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Frequently Asked Questions

Q What is Shannon entropy?

Shannon entropy measures the randomness/information density of data. Higher values mean more random/compressed data, lower values mean more structured/repetitive data.

Q What does entropy tell me about a file?

Text files: 3-5 bits/byte. Compressed/encrypted files: 7-8 bits/byte. Highly structured data: 1-3 bits/byte.

Q Is the entire file analyzed?

Only the first 8KB is analyzed for entropy and hex header. File metadata (name, size, type) is read instantly.

Q What about EXIF data for images?

EXIF metadata is not currently extracted. The tool focuses on general file properties.

Q Can I view metadata for multiple files?

Currently one file at a time. Upload a new file to replace the current analysis.

About This Tool

File Metadata Viewer is a free online tool by FreeToolkit.ai. All processing happens directly in your browser — your data never leaves your device. No registration or installation required.