erikrose/parsimonious

Health v2 · maintenance only

Flags: no_releases

Adoption not part of the score

1916 stars · 138 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

Parsimonious is a pure-Python parsing library based on parsing expression grammars (PEGs), letting you define grammars in a simplified EBNF notation and produce parse trees. It emphasizes speed, low memory use, readable grammars, and good error reporting, with a NodeVisitor API for walking resulting trees.

Use cases

• parse a custom DSL in python
• build a parser for a config file format like ini
• write a wiki markup to HTML converter
• define a grammar in EBNF and get an AST
• implement a packrat parser without C extensions
• parse structured text with arbitrary lookahead

When to choose

• you need a pure-Python parser with no compiled dependencies
• you want readable, extensible grammars in EBNF-like notation
• you need arbitrary-lookahead PEG parsing with good error messages
• you want to separate grammar recognition from tree transformation

When to avoid

• you need maximum parsing speed and can accept C-based tools like Lark or ANTLR
• you need left-recursive grammar support
• you are parsing very large inputs where memory is critical

Facets

library · maturity active

parser parsers programming-languages developer-tools python cross-platform peg packrat grammar ebnf syntax-tree pure-python

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