LZ77 sliding-window matcher

At each position the encoder searches the window (blue) for the longest match with the lookahead (gray). Matches of 3+ symbols become an (offset, length) backreference; shorter ones stay literals.

Text Window W Max match L

Blue = sliding window (already emitted, still searchable) · green = last match · gray = lookahead · blue outline = current position.

Huffman Coding Tree Builder

Enter symbol probabilities, then build the optimal prefix-free code.

Enter probabilities and click "Build Tree".