EBNF Online Validator

The tool analyzes EBNF grammar text to ensure syntactic correctness and structural soundness. It tokenizes grammar constructs, identifies nonterminals and terminals, and builds an internal representation that supports further checks. By separating production definitions and references, it helps users spot undefined symbols and circular dependencies early.
Core capabilities include syntax validation, undefined symbol detection, duplicate productions, and left-recursion warnings. It supports common EBNF forms such as group (), optional [], repetition {}, and alternation |, and can flag potential issues like missing terminators or mismatched brackets. An advanced mode can report potential ambiguities and generate a simplified parse outline.
Intended to assist grammar authors, tool integrators, and educators by delivering actionable error details and a machine-readable result set. The tool does not execute grammars or generate code; it strictly validates syntax and structure to improve reliability of downstream parsers and documentation.