Developer Tools
Format TOML Files
Transform pasted text with the toml formatter and copy the cleaned output.
Direct Answer
Use the TOML Formatter when a TOML config file, such as a Cargo manifest or a pyproject file, has inconsistent spacing or grew messy after repeated hand edits. It normalizes spacing around keys, tables, and arrays while preserving every value and table exactly as declared.
Tables, Inline Tables, and Arrays of Tables
TOML has several ways to represent grouped data, and each has a distinct syntax that formatting must respect rather than convert between.
- A bracketed section header defines a single table; repeating the same header for the same path is a duplicate-key error.
- A double-bracketed header defines an array of tables, adding a new entry each time that header appears.
- An inline table with curly braces must stay on one line and is best for small, simple groupings.
- Dotted keys are shorthand for nested tables without writing a full separate table header.
Why Teams Choose TOML Over YAML for Config
TOML was designed specifically to avoid some of the ambiguity that shows up in hand-written YAML.
- Indentation in TOML is cosmetic only, not structural, so a stray space never changes meaning.
- There is no equivalent of YAML's Norway problem; bare words like on, off, yes, and no are always strings, never implicit booleans.
- Native datetime literals avoid needing to quote and manually parse dates.
- Every value's type is explicit from its syntax, removing a whole category of implicit-conversion bugs.
How to Use Toml Formatter
- Paste or type your content into the input box.
- The transformed result appears instantly in the result panel below.
- Click Copy result to copy the output to your clipboard.
- Download .txt saves the transformed text as a file.
- Reset clears everything and lets you start over.
Reference
| Feature | Details |
|---|---|
| Purpose | Transform pasted text into a cleaner or different format. |
| Input | Text, lines, lists, or copied content. |
| Result | Transformed text ready to copy or download. |
| Best for | Cleanup, formatting, list preparation, and copy-paste workflows. |
| Category | Developer Tools |
| Works on | Desktop, tablet, and mobile browsers |
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Frequently Asked Questions
What is the difference between a single bracket and a double bracket table header?
A single bracketed header, like a section name in brackets, defines one table, and defining the same header twice is a duplicate-key error in most parsers. A double bracketed header defines an array of tables, so each time that exact header appears in the file it appends a new table entry to an array, which is how TOML represents repeatable blocks such as multiple server or dependency entries.
What is an inline table used for?
An inline table written with curly braces on one line, such as a key set to a small object with a couple of fields, is meant for compact, simple groupings that do not need their own full table header. Unlike a regular table, an inline table cannot span multiple lines, so it is best kept short.
Why is TOML often preferred over YAML for configuration?
TOML's syntax has no significant whitespace ambiguity since indentation is purely cosmetic, not structural, so a misaligned space never changes what the file means. It also has no equivalent of YAML's implicit type coercion for common words like yes, no, on, and off, which removes an entire category of subtle configuration bugs where a value silently becomes a boolean.
How do I write dates and times in TOML?
TOML has a native datetime literal format, written without quotes, and parsers read it directly into a real datetime type rather than a string. This differs from YAML or JSON, where you would typically need to quote the value and parse it manually in your application code.
Why does a dotted key create a nested table?
A dotted key, such as a key with a subkey joined by a period, is shorthand in TOML for defining a nested table inline, equivalent to writing a separate bracketed table containing that subkey. Mixing dotted key syntax and an explicit bracketed header for the same path in the same file causes a duplicate key error, since both are defining the same table.
Can I have duplicate table headers?
No, defining the same single bracketed table twice is invalid TOML and most parsers reject it outright with a duplicate key or table error. This is different from YAML, where a later duplicate key can silently override an earlier one without any error.
Why does formatting seem to reorder my keys?
A correct formatter should preserve the original order of keys within each table and only adjust spacing and indentation; if you see keys reordered, the tool may be sorting keys alphabetically rather than simply reformatting them. Check whether the formatter has a sorting option enabled that you did not intend to use.
What value types does TOML support?
TOML supports strings, integers, floats, booleans, datetimes, arrays, and tables, and every value has an explicit type derived directly from its syntax, such as quotes for strings or bare digits for numbers. This removes the ambiguity found in formats where a bare word could be interpreted as more than one type depending on the parser.