Pigpen cipher

Encode mode walks the input, keeps alphabetic characters, and emits space-separated tokens such as grid_b for H and grid_c for E; decode mode accepts those tokens in any common letter case, ignores extra whitespace, and rebuilds the message only when every token is known. An unknown symbol, an empty payload, or a string with no letters to encode fails with invalid_input and names the problem instead of guessing. Use it free in the browser for history-of-crypto lessons, scavenger-hunt worksheets, and freemason-symbol demos, or call the API at $0.002 per successful request when pipelines need reproducible Pigpen transforms.

What the Pigpen cipher is and how tokens represent the symbols

The Pigpen cipher, also called the Masonic cipher or freemason cipher, is a classical monoalphabetic substitution that replaces each Latin letter with a geometric mark taken from a pair of three-by-three grids and a pair of X-shaped figures. In the textbook freemason layout used here, the first grid holds A through I without dots, the second grid holds J through R with a central dot in each cell, the first X figure holds S through V on its four diagonal arms without dots, and the dotted X holds W through Z. Historically those marks were drawn by hand as incomplete box walls or angled strokes; this product cannot assume a shared Unicode glyph set, so every mark is rendered as a stable descriptive token such as grid_tl for the top-left plain cell, grid_c_dot for the center dotted cell, x_ne for the north-east plain X arm, and x_sw_dot for the south-west dotted arm. That fixed twenty-six entry mapping is exactly what this endpoint applies: there is no keyword stream, no modular shift, and no optional alphabet file that could drift between locales. The JSON response always includes result for the transformed string, encoding fixed to pigpen, mode set to encode or decode, input_length and output_length for the raw strings you sent and received, letter_count and token_count for how many A–Z letters or symbols were produced or consumed, plus alphabet and formula strings that restate the grid and X rule for documentation and automated checks. There is no streaming path and no silent fallback to Polybius digits, Bacon a/b groups, or a Caesar shift: either the payload is valid for the chosen mode, or the request fails with invalid_input. If you need digit-pair squares, biliteral codes, or modern authenticated encryption, use those dedicated endpoints; this landing answers only the classical Pigpen grid-and-X contract that puzzle books and freemason history chapters already describe.

How text and mode are read and how unknown symbols are reported

In decode mode the string is split on whitespace into tokens, each token is lowercased, and every token must appear in the twenty-six symbol vocabulary. The preferred payload fields are text for the message or ciphertext and optional mode for encode or decode. Text accepts aliases such as input, value, s, message, plaintext, and ciphertext 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 for encode and dec, decrypt, d for decode; any other string fails validation. In encode mode only alphabetic letters are kept and mapped, case is ignored on the way in, and the result is lowercase tokens separated by single spaces; if no letter remains after filtering, the engine rejects the request with invalid_input so a digit-only string does not look like a successful empty cipher. When one or more tokens are not recognized, the request fails with invalid_input and the message explicitly lists the unknown Pigpen symbol or symbols rather than dropping them or inventing a letter. That report is the product requirement behind “reports unknown symbols”: solvers and graders learn which mark was wrong instead of receiving a silently truncated plaintext. Missing text, empty text, non-string types, strings longer than the documented maximum, and unknown modes likewise 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 of $0.002.

Where Pigpen fits in lessons, hunts, and test fixtures

Frontend teams can show encode and decode side by side so learners see that grid_b grid_c grid_l grid_l grid_r is exactly HELLO without inventing a custom table. 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.