What does Shannon entropy tell me?

Shannon entropy measures information density from 0 to 8 bits per byte. Plain text sits around 4 to 5, compressed data around 7, and encrypted or random data approaches 8. A near-8 value strongly suggests encryption or compression.

How does string extraction work?

The inspector scans for runs of printable ASCII bytes (0x20 to 0x7e) at least four characters long, the same idea as the classic strings command. This surfaces embedded text such as URLs, error messages and metadata.

What is the entropy heatmap for?

The file is split into equal blocks and each block's entropy is colored from green (ordered) to red (random). This reveals structure, for example a low-entropy header followed by a high-entropy compressed or encrypted body.

Is there a size limit?

Yes, files are capped at 16 MB so the in-browser analysis stays responsive. For larger files, inspect a representative slice or use a desktop tool like binwalk.

No. Everything is computed in your browser with FileReader, so the file's contents never leave your device. That makes it safe for proprietary or sensitive binaries.

Binary File Inspector

When you are handed an unknown binary — a firmware image, a cache file, a custom save format — three quick measurements tell you a lot before you ever open a hex editor: what readable text it contains, how its bytes are distributed, and how random each region is. This inspector computes all three in your browser so you can characterize a file at a glance.

How it works

The tool reads the file into a byte array and runs three analyses:

String extraction finds runs of printable ASCII (0x20–0x7e) of at least four characters, the same approach as the Unix strings command. This surfaces embedded URLs, file paths, error messages and metadata.
Byte-frequency histogram counts how often each of the 256 possible byte values appears. Text files spike around the ASCII range; compressed or encrypted files look nearly flat.
Shannon entropy is computed both overall and per fixed-size block. Entropy H = -Σ p·log2(p) ranges from 0 bits per byte (a single repeated value) to 8 bits per byte (uniformly random). The per-block values are drawn as a heatmap from green (ordered) to red (random).

How to read the results

A low overall entropy (under ~4.5) usually means text, source code or sparse structured data. Values around 6–7 point to media or compressed content, and anything above ~7.5 is the signature of encryption, compression, or packed data. The heatmap adds spatial detail: a common pattern is a low-entropy header or table near the start, followed by a solid red block where the compressed or encrypted payload lives. Combine that with the extracted strings — a magic word, a library version, a copyright notice — to identify the format. All of this runs locally, so even confidential files never leave your device.