File Hider Extractor
Extract hidden files from polyglot carriers. Browser-based binwalk alternative with auto-detect, AES decryption, and visual hex map.
Drop carrier file or click to browse
JPEG, PNG, MP3, PDF, or any file (max 500MB)
Try the demo instantly — no upload needed
Loads a pre-encoded PNG with hello.txt hidden inside.
jpeg
png
mp3
How to Extract Hidden Files (4 steps)
- Upload a carrier file you suspect contains a hidden payload
- Optionally enter the encryption password
- Click Decode — the tool scans for the EP_STEGO marker and extracts what's inside
- Download the recovered file (or unzip the bundled archive)
File Extraction Methods — What This Tool Detects
| Method | Technique | Advantage | Best For |
|---|---|---|---|
| EOF Append | Adds payload after the carrier's natural end-of-file marker | Carrier opens normally in any viewer · unlimited capacity | Default — JPEG/PNG/MP3/PDF/anything |
| PNG Chunk Injection (stEG) | Inserts payload as a custom 'stEG' chunk before IEND with a valid CRC32 | Survives some PNG re-saves · invisible to file-size checks | Hardened CTF challenges, archival images |
| Multi-file ZIP | JSZip-bundles multiple input files before embedding | Same wire format · transparent to the user | Hiding 2+ files at once |
| AES-256-GCM | Encrypts the payload before appending | Wrong password silently rejected · plausible deniability | Encrypted exfil / CTF challenges |
| Reed-Solomon Redundancy | Wraps the payload in shard-based redundancy (RS-10/20/30) | Survives 10–30% trailing-data corruption | Unreliable transfer / archival storage |
| EP_STEGO marker | 8-byte magic header + 1B flags + 4B BE length | Decoder auto-locates and extracts | Round-trip with this decoder |
Frequently Asked Questions
What does this decoder look for?
It scans the file for the EP_STEGO marker the encoder writes, reads the flags + length, and extracts the payload. It also detects PNG stEG chunks and unwraps Reed-Solomon redundancy when present.
What if no marker is found?
Either the file is clean, or it was hidden with a different tool. Try a different decoder for tools like binwalk-style polyglots that use no marker.
What if the payload looks like noise?
It's probably encrypted. Enter the password used during encoding and try again — wrong passwords return garbage rather than an error.
Does this support multi-file payloads?
Yes. If the encoder bundled multiple files into a ZIP, the decoder unpacks them automatically and lets you download each one.
Is anything uploaded?
No. Decoding is 100% local using ArrayBuffer scanning, JSZip, and the Web Crypto API.
Related Tools
File Hider
Hide any file inside another file (JPEG, PNG, MP3, PDF). Creates polyglot files that open normally but contain hidden payloads. AES-256 encrypted.
Steganography Detector
Statistical steganalysis using four algorithms — chi-square, RS analysis, sample pairs, primary sets. StegExpose-equivalent. Payload size estimate. Method fingerprint. WAV audio support. No upload.