Image Steganography Hide secret text messages inside images using LSB steganography, or reveal hidden messages.

What Is Steganography?

A steganography tool that hides text messages inside images by modifying the least significant bits (LSBs) of pixel color values. The changes are visually imperceptible — the encoded image looks identical to the original. The tool encodes the message length as a 32-bit header followed by UTF-8 text bytes spread across RGB channel LSBs. Use PNG format to preserve the hidden data without compression artifacts.

Why Use Steganography?

• Visually undetectable — encoded image looks identical
• Encode and decode modes in one tool
• UTF-8 support for international characters
• Must use PNG format to preserve hidden data

Common Use Cases

Secret Communication

Share hidden messages inside ordinary-looking images.

Digital Watermarking

Embed invisible ownership information in images.

Education

Learn about steganography and information hiding.

CTF Challenges

Create or solve steganography challenges.

Technical Guide

Encoding: The message is converted to UTF-8 bytes. A 32-bit length header is prepended. Each bit is stored in the LSB of successive RGB channel values (skipping alpha). The LSB is cleared with AND 0xFE then OR'd with the message bit. Decoding: LSBs are read from RGB channels. First 32 bits give the message length. Subsequent bits are assembled into bytes and decoded as UTF-8. Only PNG preserves LSBs — JPEG compression destroys the data.

Tips & Best Practices

• 1
  Always save as PNG — JPEG compression destroys hidden data
• 2
  Larger images can hold longer messages
• 3
  The encoded image is visually identical to the original
• 4
  Share the decode mode URL so recipients can reveal messages

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Frequently Asked Questions

Q Detectable?

Visually no. Statistical analysis can detect LSB modification.

Q Message length?

Limited by image size: (width × height × 3 - 32) / 8 characters max.

Q JPEG support?

No — JPEG compression destroys LSB data. Use PNG only.

Q Encryption?

Message is not encrypted. Encrypt your text before hiding for security.

Q Image quality?

No visible change — only the least significant bit of each channel is modified.

About This Tool

Steganography 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.