# meriyah/meriyah

A 100% compliant, self-hosted javascript parser  - https://meriyah.github.io/meriyah

Repository: https://github.com/meriyah/meriyah
Canonical: https://ross.abutalabs.com/products/meriyah
Language: TypeScript
License: ISC
License Family: permissive
Topics: ecmascript, parsing, estree, tc39, stability, esnext, parser, ast, jsx, acorn, performance, javascript, typescript
Last push: 2026-08-25T22:22:49+00:00

## Health v2 (maintenance only)
Score: 99/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 98, longevity 100
- inputs: {"age_days": 2675, "days_push": 8, "days_rel": 16, "gap_med": 7, "n_releases_24m": 20}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1215, forks 59 (observed 2026-08-28T04:04:01.110822+00:00)

## What it is
Meriyah is a fully ECMAScript 2024-compliant, self-hosted JavaScript parser written in TypeScript that emits ESTree-compatible ASTs. It focuses on performance and stability, supports JSX and stage 3 proposals via options, and is already used in production.

## Use cases
- parse javascript source code into an ast
- build a javascript linter or code analyzer
- parse jsx in a build tool
- analyze ecmascript syntax for a transpiler
- detect syntax errors in js files
- walk and transform javascript asts
- parse latest tc39 stage 3 syntax

## When to choose
- you need a spec-compliant JavaScript parser with ESTree output
- you want JSX support and optional stage 3 proposal parsing
- performance and low memory usage matter for large codebases
- you need a stable, production-proven parser without TypeScript/Flow syntax

## When to avoid
- you need to parse TypeScript or Flow syntax
- you need consistent RegExp validation across old runtimes
- you need a parser that backtracks or handles non-standard syntax

## Facets
- artifact type: library
- maturity: stable
- function: parser, developer-tools
- domain: parsers, programming-languages, web-development, developer-tools
- platform: browser, cross-platform
- tags: estree, ecmascript, ast, jsx, esnext, tc39, javascript-parser, no-backtracking, nodejs, javascript, typescript

## Member repositories
- meriyah/meriyah (main) score 99

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:01.110822+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 2026-08-30T06:17:17.092140+00:00, confidence not recorded.
  - readme: https://github.com/meriyah/meriyah (fetched 2026-08-28T04:04:01.110822+00:00, sha a0430c1b32af)
- Data as of 2026-08-30T08:39:29.467469+00:00.