TOML tools
Format, validate, and round-trip TOML against JSON or YAML — everything runs in your browser. Your text never leaves the page.
Inspect
Formatter →
Canonical spacing, quoting, and table layout. Re-emits the parsed tree.
Validator →
Pin syntax errors to the exact line and column. Shows normalized structure.
Diff →
Compare two TOML files semantically — ignores whitespace and key order.
Merge →
Combine a base TOML with an overlay. Deep-merge tables; pick a conflict and array policy.
Convert
TOML→JSON →
Tables and arrays into clean JSON. Preserves types verbatim.
JSON→TOML →
Readable TOML out of a JSON object, with hierarchies intact.
TOML→YAML →
YAML 1.2 output, for cross-format config workflows.
YAML→TOML →
Migrate back without surprises — same types, same shape.
INI→TOML →
Migrate legacy INI configs. Dotted sections become nested tables.
TOML→INI →
Backport TOML to a classic INI file for legacy systems.
.env→TOML →
Build a structured config from environment variables. __ nests.
TOML→.env →
Flatten a TOML config to KEY=VALUE pairs for Docker and 12-factor apps.
TOML→TypeScript →
Emit typed .d.ts interfaces matching the shape of your config.
Transform
- What is TOML — plain-English reference: types, ecosystem, and how it compares to JSON and YAML.
- Sample datasets — real
Cargo.toml,pyproject.toml, and intentionally-broken files for testing.
Converting between formats
If you need to pipe your config into a web service or another tool, the TOML → JSON converter turns your tables and arrays into clean JSON without sending a single byte to a server. Going the other way, the JSON → TOML converter creates a readable TOML structure from a JSON object while keeping your data hierarchies intact. For mapping between different config styles, the TOML → YAML converter handles YAML 1.2 output, and the YAML → TOML converter helps you migrate back to TOML with zero friction.
Cleaning and checking your TOML
To keep your config files consistent, the
TOML Formatter
applies canonical spacing, standardized quoting, and a logical table layout to your documents.
If you are hunting for a syntax error, the
TOML Validator
identifies the exact line and column where your TOML failed to parse and shows you a normalized structure once it is valid.
What they have in common
Everything runs in your browser. The text you paste never leaves your machine because there is no server-side component handling your data. I can't see your configuration because it was never sent to me, which means no size caps and nothing for me to accidentally leak.
Sensible defaults, no surprises. These tools aim for a "least astonishment" approach where your types and values stay exactly as you wrote them. Nothing gets silently transformed or "helpfully" changed without you asking.
Free to use. Bug reports and feature requests are always welcome — drop me a line at [email protected].
— S., [email protected]