FILE FORMAT GUIDE
TOML File (.TOML): Tables, Types & Reading Settings
A TOML file expresses configuration as keys, values and tables. Its explicit table headers make nested settings readable without relying on indentation for their meaning. Read it with a TOML parser compatible with the document's language version; successful parsing still does not verify an application's expected settings.
Check supported header evidence locally. Identification is not file validation or a malware scan.
Analyze a file locallyQuick facts
- Extension
- .toml
- Format
- TOML
- Category
- data
- MIME type
- application/toml
- Standard / developer
- Unknown
- Open with
- Python tomllib
What is TOML?
TOML 1.0 defines strings, numbers, booleans, arrays, tables and date/time types. A key cannot be assigned repeatedly. Table syntax organizes a document into a mapping, rather than a spreadsheet. This guide covers TOML 1.0 behavior and the documented Python tomllib reader, not every later language revision or parser extension.
- Write human-edited application configuration
- Read TOML 1.0 settings programmatically in Python
How to open TOML
The reviewed opener is a programmatic reader, not a standalone viewing app. No unreviewed graphical editor or writing support is implied.
Python tomllibPython standard library (3.11+)
Open the file as a readable binary stream and pass it to tomllib.load. Invalid TOML raises TOMLDecodeError. Limit the size of untrusted documents before parsing. The module handles TOML 1.0 and returns Python data; it does not save edits or confirm application-level configuration rules.
Technical details
- Signature
- Not reviewed
- Encoding
- UTF-8 (TOML 1.0)
- Container
- Not reviewed
- Compression
- Not reviewed
Things to check
- Duplicate key definitions are invalid.
- Python tomllib reads TOML 1.0 but does not write it.
Related formats
- YAML
Another human-edited configuration format with different nesting and scalar conventions.
- JavaScript Object Notation
An alternative structured data syntax when the consuming application expects JSON rather than TOML tables.
- Extensible Markup Language
A markup-oriented alternative for structured configuration; the target application's schema decides suitability.
Sources & review
Fact review: 2026-09-18. Unknown fields are not inferred from the file extension.