How to use the TOML Converter
- Choose the direction — for example TOML → JSON.
- Paste your file; it converts as you type and syntax errors show the line and column.
- Copy or download the result.
About TOML
TOML (Tom’s Obvious, Minimal Language) is a config format built to be easy to read: key = "value" pairs, [tables] for sections and [[arrays of tables]] for lists of objects. Rust’s Cargo.toml, Python’s pyproject.toml, Hugo, Netlify and many CLIs use it. This converter follows TOML 1.0.
How types convert
Strings, numbers, booleans, arrays and tables map directly to JSON and YAML. TOML has native dates and times; JSON has none, so they become ISO 8601 strings. Converting JSON or YAML to TOML needs an object at the top level — TOML documents are always tables — and null values are skipped, because TOML has no null.
Common TOML errors
- Defining the same key or table twice.
- Strings without quotes —
name = devpackmust bename = "devpack". - Mixing a table and a dotted key for the same name.
Private by design
Conversion runs entirely in your browser — your code is never uploaded, so it’s safe for proprietary projects.
Tools that pair well with the TOML Converter
- YAML to JSON — Paste YAML — a Compose file, Kubernetes manifest or CI config — and get formatted JSON.
- YAML Validator — Paste a Docker Compose file, Kubernetes manifest, GitHub Actions workflow or any YAML to pinpoint errors, catch common pitfalls and get a cleanly formatted version.
- .env File Validator — Paste a .env file to find invalid keys, duplicates, empty values and quoting mistakes, compare it with .env.example to spot missing variables, and generate a safe example file.
- JSON Schema Validator — Paste a schema and some JSON to see exactly which values break which rule — or generate a starting schema from example data.
Frequently asked questions
How do I convert pyproject.toml or Cargo.toml to JSON?
Paste the file with TOML → JSON selected. Sections like [tool.poetry] or [dependencies] become nested JSON objects.
Why are my dates strings in the JSON?
JSON has no date type, so TOML dates and times are written as ISO 8601 strings, which every JSON library can parse.
Why can’t I convert a JSON array to TOML?
A TOML document is always a table (an object). Wrap the array in an object, for example {"items": [...]}, and it becomes an array of tables.
Can I install TOML Converter as a web app and use it offline?
Yes. TOML Converter is an installable web app (PWA) — installed from your browser, not downloaded from an app store. Click Install app at the top of this page in Chrome or Edge (Windows, macOS, Linux, ChromeOS) or on Android, use Share → Add to Home Screen on iPhone and iPad, or File → Add to Dock in Safari 17+ on a Mac. It then opens in its own window with its own icon, and because it runs entirely in your browser it keeps working offline. Firefox on desktop can’t install web apps. How installing works.