Metadata Steganography Hider
Hide text or files in PNG text chunks, PDF metadata fields, GIF comments, MP3 ID3 tags, or DOCX/XLSX custom properties. No pixels touched. AES-256-GCM.
Try the demo instantly
Loads a 200×200 demo PNG — no upload needed
Drop your PNG, GIF, PDF, MP3, or DOCX/XLSX here
JPEG not supported here — use the EXIF Data Hider
100% Client-Side Processing
Your file is processed entirely in this browser tab. Nothing is uploaded to any server.
How to Hide Data in File Metadata (5 steps)
- Upload a PNG, GIF, PDF, MP3, or DOCX/XLSX file — it's analysed instantly
- Choose where to hide (PNG tEXt chunk is recommended for images)
- Type your secret message or upload a file to hide
- Add a passphrase for AES-256 encryption (recommended)
- Click Embed — download the file with hidden metadata
Metadata Steganography — 8 Hiding Targets Compared
| Target | Mechanism | Capacity | Best For |
|---|---|---|---|
| PNG tEXt chunk | ASCII key=value chunk before IEND | Unlimited | Short messages, CTF flags — the #1 PNG hiding location |
| PNG iTXt chunk | UTF-8 text, optional zlib compression | Unlimited | Longer messages, international characters |
| PNG zTXt chunk | Always zlib-compressed ASCII | Unlimited (compressed) | Large text payloads, best size/capacity ratio |
| PNG custom chunk | Private ancillary chunk, binary-safe | Unlimited | Binary payloads, advanced CTF hiding |
| PDF metadata field | Info dictionary (Author, Keywords, ...) | ~32 KB per field | Document watermarking, invisible fingerprinting |
| GIF comment | Comment Extension block (0x21 0xFE) | Unlimited | GIF-specific CTF challenges |
| MP3 ID3 tag | TXXX/COMM/PRIV/USLT frame | Unlimited | Audio file watermarking |
| DOCX/XLSX property | Custom document property (docProps/custom.xml) | ~1 MB | Office document fingerprinting |
Frequently Asked Questions
How is this different from the EXIF Data Hider?
EXIF Data Hider targets JPEG-specific fields: UserComment, ImageDescription, GPS coordinates, IPTC caption. This tool targets non-JPEG metadata surfaces: PNG tEXt/iTXt/zTXt/custom chunks, PDF Info dictionary fields, GIF comment extensions, MP3 ID3 tags, and DOCX/XLSX custom properties. Use EXIF Data Hider for JPEG files.
Will the file look different after embedding?
No. PNG and GIF metadata injection adds data to the header layer — zero pixel values are modified. Audio and document content is unchanged. File size increases slightly by the size of the embedded field.
Can exiftool detect what I've hidden?
ExifTool will show that the field exists and display its value — the MSTEG header plus your AES-encrypted payload, which looks like random base64 text. ExifTool cannot decrypt AES — the content is unreadable without your passphrase.
Does metadata survive social media upload?
Typically no. Most social platforms (Instagram, Twitter/X, Facebook, Discord image upload) strip metadata when processing uploaded images. Share the file as an attachment instead — email, Google Drive, Dropbox, or Telegram file transfer preserve metadata intact.
What's the MSTEG header for?
Every encoded file includes a 16-byte MSTEG v1 header (target, encryption flag, compression flag, payload length, CRC32) embedded alongside your payload. The Metadata Steganography Extractor scans every metadata field for this header automatically — zero configuration needed to decode. You can turn it off in Forensic mode for CTF-style headerless hiding.
What happens if my payload doesn't fit?
PDF fields cap out around 32 KB. You'll see a capacity warning with an 'Auto fix for me' button that enables compression, or you can manually pick a different target (PNG/GIF/MP3/DOCX all have effectively unlimited capacity).