# jneen/parsimmon

A monadic LL(infinity) parser combinator library for javascript

Repository: https://github.com/jneen/parsimmon
Canonical: https://ross.abutalabs.com/products/parsimmon
Language: JavaScript
License: MIT
License Family: permissive
Last push: 2023-04-14T23:41:19+00:00

## Health v2 (maintenance only)
Score: 23/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 8, longevity 100
- inputs: {"age_days": 5036, "days_push": 1237, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1273, forks 128 (observed 2026-08-28T04:04:12.361204+00:00)

## What it is
Parsimmon is a small monadic LL(infinity) parser combinator library for JavaScript, inspired by parsec and Promises/A+. It lets you build large parsers from many small composable parsers, running in Node.js and browsers (IE7+).

## Use cases
- write a parser for a custom DSL in javascript
- parse JSON-like configuration files in node
- build a lisp or math expression parser
- parse custom text formats with combinators
- implement a small programming language parser in the browser
- tokenize and parse structured text without regex soup

## When to choose
- you want a lightweight, dependency-free parser combinator library in JavaScript
- you need to parse small custom languages or formats in Node or the browser
- you prefer a parsec-style monadic API over grammar-generator tools

## When to avoid
- you need an actively maintained library with ongoing bug fixes (the project is explicitly unmaintained)
- you need maximum parsing performance for large grammars
- you want a grammar-file-based parser generator like ANTLR or PEG.js

## Facets
- artifact type: library
- maturity: abandoned
- function: parser
- domain: parsers, programming-languages, developer-tools
- platform: browser, cross-platform
- tags: parser-combinators, monadic, javascript, unmaintained, nodejs

## Member repositories
- jneen/parsimmon (main) score 23

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:12.361204+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T05:03:13.088709+00:00, confidence not recorded.
  - readme: https://github.com/jneen/parsimmon (fetched 2026-08-28T04:04:12.361204+00:00, sha 8ecae90a87f1)
  - registry_npm: https://registry.npmjs.org/parsimmon (fetched 2026-08-29T12:14:27.003266+00:00, sha 63c88e301352)
- Data as of 2026-08-30T08:39:29.467469+00:00.