From Wikipedia, the free encyclopedia
Filename extension
Internet media typeNot registered[1]
Developed byTom Preston-Werner
Initial release23 February 2013; 11 years ago (2013-02-23)
Latest release
12 January 2021; 3 years ago (12 January 2021)
Type of formatData interchange
Open format?Yes Edit this at Wikidata

Tom's Obvious, Minimal Language (TOML) is a file format for configuration files.[3] It is intended to be easy to read and write due to obvious semantics which aim to be "minimal", and it is designed to map unambiguously to a dictionary. Originally created by Tom Preston-Werner, its specification is open source. TOML is used in a number of software projects[4][5][6] and is implemented in many programming languages.[7]


TOML's syntax primarily consists of key = value pairs, [section names], and # (for comments). TOML's syntax somewhat resembles that of .INI files, but it includes a formal specification, whereas the INI file format suffers from many competing variants.

Its specification includes a list of supported data types: String, Integer, Float, Boolean, Datetime, Array, and Table.


# This is a TOML document.

title = "ImpalaPay Co."

server = ""
ports = [ 8000, 8001, 8002 ]
connection_max = 5000
enabled = true

# Line breaks are OK when inside arrays
hosts = [


  # Indentation (tabs and/or spaces) is allowed but not required
  ip = ""
  dc = "eqdc10"

  ip = ""
  dc = "eqdc10"

Use cases[edit]

TOML is used in a variety of settings (some related to its creator), such as:


TOML has been criticized on a number of points:[11][12]

  • TOML is verbose; it is not DRY and syntactically noisy.
  • TOML's hierarchies can be difficult to infer from syntax alone.
  • Overcomplication: Like YAML, TOML has too many features.
  • In TOML the syntax determines the data types ("syntax typing").

See also[edit]


  1. ^ There is a mime type proposal for TOML consisting in application/toml, but this has never been officially registered among IANA's Media Types.
  2. ^ "Release 1.0.0". 12 January 2021. Retrieved 17 January 2021.
  3. ^ Preston-Werner, Tom; Gedam, Pradyun (January 11, 2021). "TOML: English v1.0.0". Retrieved January 27, 2024.
  4. ^ "The Manifest Format - The Cargo Book".
  5. ^ Drew DeVault (2021-07-28). "My wish-list for the next YAML". YAML is both universally used, and universally reviled. It has a lot of problems, but it also is so useful in solving specific tasks that it's hard to replace. Some new kids on the block (such as TOML) have successfully taken over a portion of its market share, but it remains in force in places where those alternatives show their weaknesses.
  6. ^ "TOML: Tom's Obvious Minimal Language". Retrieved 2022-08-08.
  7. ^ "toml-lang/toml". GitHub. 23 May 2022.
  8. ^ "tomllib — Parse TOML files". Python documentation. Retrieved 2023-07-08.
  9. ^ "The Manifest Format - The Cargo Book". Retrieved 2023-07-08.
  10. ^ "10. Project.toml and Manifest.toml · Pkg.jl". Retrieved 2023-07-08.
  11. ^ What is wrong with TOML?
  12. ^ An INI critique of TOML

External links[edit]