TOML Validator

How to use this developer tool

1. Paste or upload the toml source you want to inspect.
2. Run Validate TOML, or press Ctrl/Cmd + Enter.
3. Read the summary, diagnostics, and reported counts before using the output.
4. Copy the result or download it in the shown format.

What this developer tool does

Each non-comment line is classified as a table header, array-table header, or key-value assignment. Values are parsed by type and keys are checked for duplicates within their table.

A Valid result means the file passed this validator’s documented subset. It is not a substitute for loading the file with the exact TOML library used by your application.

Example

The Sample button loads a representative toml source. Running it produces the same kind of validation report shown in the result panel, including counts that are calculated from the supplied text rather than fixed examples.

title = "Service"
enabled = true
[server]
host = "127.0.0.1"
port = 8080
features = ["metrics", "health"]

Use cases

• Review configuration changes before committing them.
• Diagnose format-specific problems in CI or deployment inputs.
• Create a copy-ready result for documentation or another developer tool.
• Check generated files without exposing project data to a remote service.

Tips for reliable output

• Start with the smallest input that reproduces a problem.
• Keep a copy of the original before replacing configuration files.
• Read warnings and limitations, even when the main result succeeds.
• Validate the output again with the parser used by your application.
• Use UTF-8 when saving downloaded text.

Processing details

The validator does not execute code or contact a server. It creates a temporary object solely to catch conflicting tables and show the parsed shape.

Multiline strings, dotted quoted keys, special floats, non-decimal integers, and every edge of the TOML 1.0 grammar are outside this lightweight implementation.