Steganography Tool

Hides secret text messages inside PNG/JPEG/BMP/WebP images using LSB (least significant bit) steganography, and extracts them back. The message is UTF-8 encoded, prefixed with a 4-byte big-endian length header, and embedded one bit at a time into the red channel of each pixel. The result is downloaded as a lossless PNG.

1. Choose Hide or Reveal mode. 2. Click the drop zone or drag in an image (PNG, JPEG, BMP, or WebP). A preview and the dimensions appear; the X button clears it. 3. In Hide mode, type your secret message into the textarea. A live capacity counter shows used vs. available bytes and turns red if you exceed the limit. Click Hide to embed, then Download the resulting PNG. 4. In Reveal mode, click Reveal to extract the hidden message; if no valid payload is found, the tool reports "no message".

Capacity is computed as floor((width * height) / 8) - 4 bytes: each pixel contributes one bit (its red channel's lowest bit), eight pixels form one byte, and four bytes are reserved for the length prefix. The 4-byte length header stores the message byte count big-endian. During reveal, the tool reads those 32 bits first, rejects lengths of zero or above 1,000,000, then reads exactly length*8 more bits and UTF-8 decodes them. Save as PNG because JPEG re-compression would destroy the LSB data.