extract hidden message from image
Extracting an LSB-hidden message requires knowing (or discovering) how many bits per channel were used to embed it, because reading has to start at exactly the right position. This page opens the tool already in Extract mode.
The fastest case: just pick the same value used when hiding and click extract.
Detect mode tries all 4 possible options (1 to 4 bits) and reports whether it found a valid signature, no guessing required.
LSB (least significant bit) is the technique of replacing the least important bits of each color byte with bits of your content, a change small enough that the eye usually cannot tell. This tool uses 1 to 4 of those bits in each red, green and blue channel of every pixel (the alpha channel is never touched), preceded by a 14-byte header with the magic number "STG1", a version, the content size and a CRC-32 checksum to validate extraction.
Extraction and Detect mode specifically look for this tool's own "STG1" header, so they work reliably only on images generated by it (or by another implementation of the exact same format). Images with data hidden by other steganography tools, using different header formats, will not be recognized here.
The most common causes are: the wrong bits-per-channel value (use Detect mode), the image was recompressed or resized after hiding the data (which destroys the bits, with no possible fix), or the content is encrypted and the password was not entered or is wrong. The tool indicates which of these happened in each case.
Everything happens in your browser: the image, the hidden content and the password never leave your device or pass through a server.