Comparison of Python TOML parser libraries

This page summarizes the projects mentioned and recommended in the original post on

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  • pypyr automation task runner

    pypyr task-runner cli & api for automation pipelines. Automate anything by combining commands, different scripts in different languages & applications into one pipeline process.

    The pypyr automation pipeline task-runner open-source project recently added TOML parsing & writing functionality as a core feature. To this end, I researched the available free & open-source Python TOML parser libraries to figure out which option to use.

  • Poetry

    Python dependency management and packaging made easy.

    Of the available options, only tomlkit supports style-preserving roundtrip parsing. Furthermore, tomlkit was created for the express purpose of handling TOML parsing for the poetry tool. As this is one of the 2 most popular new PEP517 & PEP518 Python build systems there is some comfort to be had in the wide adoption of a very actively used tool that means a greater likelihood of continued maintenance & support, and specifically that pyproject.toml files should parse without surprises.

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    Less time debugging, more time building. Scout APM allows you to find and fix performance issues with no hassle. Now with error monitoring and external services monitoring, Scout is a developer's best friend when it comes to application development.

  • tomli

    A lil' TOML parser

    tomli Relatively fast read-only parsing. Companion library tomli-w for writing.

  • tomlkit

    Style-preserving TOML library for Python

  • tomlplusplus

    Header-only TOML config file parser and serializer for C++17.

    Python wrapper for the toml++ C++ library.

  • toml

    Python lib for TOML (by uiri)

    toml This was initially vendored in pip itself to deal with pyproject.toml. Even so pip has since moved to tomli.

  • pytoml

    A TOML-0.4.0 parser/writer for Python.

    pytoml Abandoned by the creator for eminently sensible reasons (interesting read too... But let's not get into an argument over whether a shiny new fashion in config formats is in fact doing anything better than the previous fashions in config management...

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  • qtoml

    Another Python TOML encoder/decoder

    qtoml Still on TOML v0.5.0.

  • pytomlpp

    A python wrapper for tomlplusplus

    pytomlpp Python wrapper for the toml++ C++ library.

  • rtoml

    A better TOML library for python implemented in rust.

    rtoml Python wrapper for fast parsing written in Rust.

  • toml

    Tom's Obvious, Minimal Language

    TOMLKit only lists itself as 1.0.0rc1 compliant. Looking at the TOML spec release history delta of rc1 vs v1, it only looks like clarifications & administrative/documentation updates -there doesn't seem to be anything notable missing or functionally different in rc1 as opposed to v1. It's not impossible that I missed something, though - but given TOMLKit's wide usage via poetry, I would expect obvious out-of-date spec handling to have been noticed by someone somewhere, and I see none such in the issues list.

  • pip

    The Python package installer

    Even pip itself has moved from vendoring toml to tomli. This exodus from toml to tomli includes the very prominent:

  • typeshed

    Collection of library stubs for Python, with static types


  • black

    The uncompromising Python code formatter


  • mypy

    Optional static typing for Python


  • coveragepy

    The code coverage tool for Python


  • flit

    Simplified packaging of Python modules


  • tomli-w

    A lil' TOML writer (counterpart to

    tomli, then, seems to be where the Python community in general is coalescing for a "standard" TOML parser. tomli is read-only. For write functionality there is the companion library tomli-w.

NOTE: The number of mentions on this list indicates mentions on common posts plus user suggested alternatives. Hence, a higher number means a more popular project.

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