Ook! encoder and decoder

Encode mode builds a deterministic single-cell program that adjusts a byte cell and prints each character; decode mode tokenizes the three-token grammar, rejects odd counts and unknown pairs as invalid_input, maps the rest to Brainfuck, and executes it with a bounded tape and step limit. Use it free in the browser for esolang lessons, CTF warm-ups, and reversible joke demos, or call the API at $0.002 per successful request when pipelines need reproducible Ook transforms.

What Ook! is and what this tool returns

Ook!. This endpoint encodes ordinary text as an Ook program that, when interpreted, prints that text, and decodes by interpreting a well-formed program and collecting output characters. The JSON response always includes result for the program or recovered string, encoding fixed to ook, mode set to encode or decode, input_length and output_length for the raw strings you sent and received, command_count for how many Brainfuck instructions were produced or executed, brainfuck for the intermediate command string (useful for teaching and debugging), and a formula string that restates the three-token pair rule. There is no silent fallback to Morse, Base64, or raw Brainfuck-only mode: either the payload is valid for the chosen direction, or the request fails with invalid_input. If you need classical ciphers, binary dumps, or modern authenticated encryption, use those dedicated endpoints; this landing answers only the Ook!

How text and mode are read and how malformed pairs fail

In decode mode the source is scanned for Ook tokens with the three legal endings; only whitespace may appear between tokens. An ordered pair that is not one of the eight legal commands likewise fails as a malformed token pair rather than being skipped. Unmatched loop brackets, pointer moves outside the fixed tape, input commands that would read from stdin, and runaway loops past the step limit are also rejected. The preferred payload fields are text for the message or Ook source and optional mode for encode or decode. Text accepts aliases such as input, value, s, message, plaintext, ciphertext, and program so forms and SDK clients can reuse existing column names. Mode defaults to encode when omitted and also accepts short aliases such as enc, encrypt, e, and to_ook for encode, and dec, decrypt, d, from_ook, and run for decode; any other string fails validation. In encode mode each character must be a Latin-1 code unit in the range zero through two hundred fifty-five, length is capped for practical program size, and the engine builds a single-cell delta program: it increments or decrements from the previous cell value to the next character code, then emits a print command, then translates every Brainfuck command into a space-separated Ook pair. An odd number of tokens means a pair was cut short and always raises invalid_input with an explicit malformed token pairs message. Missing text, empty text, non-string types, code units above two hundred fifty-five on encode, and unknown modes raise invalid_input. Pair the free browser run on this page with the priced API when you need the identical mathematical result inside an automated pipeline. Invalid inputs return invalid_input and are not charged, which keeps validation cheap while successful transforms remain a fixed item price.

Where Ook! fits in lessons, puzzles, and test fixtures

On this page the work runs entirely in your browser; through the API each successful lookup costs $0.002, failed validation is not charged, and nothing is stored after the response returns. That split—free interactive exploration and a priced, identical API—matches the rest of the KIT tier-A catalog and lets you move from a classroom demo to an automated pipeline without changing the transformed result.