lark-parser
a modern parsing library
Decision gist · record as of 2026-08-14
Yes. Lark is production-stable, dependency-free, actively maintained, and widely used (top 5000 PyPI packages). Choose it if you need to parse structured text or implement a language. The main caveat: the latest release is from 2021-08-30, so verify current Python version compatibility before adopting in new projects.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Installation is straightforward with no runtime dependencies.
- The package is actively maintained with recent commits and has been stable since its first release in 2017-02-11.
License · maintenance · safety
MIT (permissive) — MIT license permits free use, modification, and distribution with minimal restrictions—suitable for both open-source and commercial projects.
last release 2021-08-30 (1810 days) · last repo commit 2026-08-13 · 5,958 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 3,665,702 downloads/mo, #2,535 on PyPI
Alternatives
Verify before relying
pip install lark-parser
from lark import Lark
grammar = r"""
start: "hello" name
name: /\w+/
"""
parser = Lark(grammar)
tree = parser.parse("hello world")- Whether the package receives active maintenance updates beyond the 2021-08-30 latest release date
- Current compatibility with modern Python versions given the last release predates recent Python releases
What it is and what it does
Lark is a general-purpose parsing library that transforms grammar definitions into working parsers. It supports three parsing algorithms—Earley (handles all context-free grammars including ambiguous ones), LALR(1) (fast and compact), and CYK (for highly ambiguous grammars)—and automatically builds parse trees from input text based on your grammar structure.
The library is designed for minimal boilerplate: you write a grammar in EBNF notation and Lark generates a parser that can immediately process text matching that grammar. It includes conveniences like automatic line and column tracking, a standard library of common terminals (strings, numbers, identifiers), and Unicode support. With no runtime dependencies and support for both Python 2 and 3, it's straightforward to integrate into existing projects.
Use it for
- Parse domain-specific languages or configuration file formats by defining their grammar rules
- Build compilers or interpreters that need to convert source code into abstract syntax trees
- Extract structured data from text by defining patterns as a context-free grammar
- Implement query languages or expression parsers for applications requiring user-defined syntax
- Generate stand-alone parsers from LALR grammars for deployment without the library
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
Lark is production-stable, dependency-free, actively maintained, and widely used (top 5000 PyPI packages). Choose it if you need to parse structured text or implement a language. The main caveat: the latest release is from 2021-08-30, so verify current Python version compatibility before adopting in new projects.
Install
lark-parser on PyPI
Before you install
Installation is straightforward with no runtime dependencies. The package is actively maintained with recent commits and has been stable since its first release in 2017-02-11.
License in practice
MIT license permits free use, modification, and distribution with minimal restrictions—suitable for both open-source and commercial projects.
Quickstart
pip install lark-parser
from lark import Lark
grammar = r"""
start: "hello" name
name: /\w+/
"""
parser = Lark(grammar)
tree = parser.parse("hello world")Verify before relying
- Whether the package receives active maintenance updates beyond the 2021-08-30 latest release date
- Current compatibility with modern Python versions given the last release predates recent Python releases
Package facts
| License | MIT permissive |
| Python support | Not specified |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | None |
| Maintenance | Actively maintained 1,810 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 3,665,702 / month, #2,535 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 5 - Production/StableIntended Audience :: DevelopersLicense :: OSI Approved :: MIT LicenseProgramming Language :: Python :: 2.7Programming Language :: Python :: 3Topic :: Software Development :: Libraries :: Python ModulesTopic :: Text Processing :: GeneralTopic :: Text Processing :: Linguistic |
Evidence: lark_parser-0.12.0-py2.py3-none-any.whl
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See also lark · lark-js · pycep-parser · spark-parser · textparser · ply · bc-python-hcl2 · rfc3987-syntax · sly · tree-sitter-python