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Authors: @jneen and @laughinghan

Maintainer: @wavebeem

Parsimmon is a small library for writing big parsers made up of lots of little parsers. The API is inspired by parsec and Promises/A+.

Parsimmon supports IE7 and newer browsers, along with Node.js. It can be used as a standard Node module through npm (named parsimmon), or directly in the browser through a script tag, where it exports a global variable called Parsimmon. To download the latest browser build, use the unpkg version. For more information on how to use unpkg, see the unpkg homepage.

Code of Conduct

Everyone is expected to abide by the Contributor Covenant. Please send reports to

API Documentation


See the examples directory for annotated examples of parsing JSON, Lisp, a Python-ish language, and math.

Common Functions


Feel free to ask a question by filing a GitHub Issue. I'm happy to help point you in the right direction with the library, and hopefully improve the documentation so less people get confused in the future.


Contributions are not just pull requests.

Issues clearly describing bugs or confusing parts of Parsimmon are welcome! Also, documentation enhancements and examples are very desirable.

Feeling overwhelmed about contributing? Open an issue about what you want to contribute and I'm happy to help you through to completion!


Thanks to @bd82 we have a good benchmark comparing Parsimmon CPU performance to several other parser libraries with a simple JSON parser example.

Fantasy Land


Parsimmon is also compatible with fantasyland. It implements Semigroup, Apply, Applicative, Functor, Chain, and Monad.