JSON ↔ YAML ↔ TOML converter — offline
Convert configs between formats without them ever leaving your browser.
Convert JSON, YAML and TOML without uploading your config
The files people convert between these formats are configuration files, and configuration files are where credentials live. A Kubernetes manifest, a CI pipeline definition, a docker-compose file, an app config — these routinely carry API keys, database URLs with embedded passwords, internal hostnames, and service account details. Pasting one into an online converter uploads all of it.
Parsing and conversion here run with open-source libraries in your browser, in any direction between the three formats, updating live as you type. Nothing is transmitted — this site has no backend, and a Content-Security-Policy blocks third-party requests. You can verify with DevTools open, or by going offline.
What each format is good at
- JSON — universal, unambiguous, and machine-first. No comments, which is precisely why it is a poor format for hand-edited configuration.
- YAML — comments, no braces, and far less punctuation, which is why the infrastructure world adopted it. The cost is significant whitespace: indentation carries meaning, so a stray space can change the structure or break the file.
- TOML — designed for configuration specifically. Explicit, hard to misread, and immune to YAML's indentation traps, at the price of being clumsy for deeply nested data.
Why a conversion sometimes fails
The three formats are not equivalent, so some conversions genuinely cannot be represented rather than merely being awkward.
TOML requires an object at the top level. A document whose root is a bare array or a single scalar has no valid TOML representation. TOML also has no null: a JSONnull has nowhere to go, so those entries cannot be carried across.
Two more worth knowing about in the YAML direction. Comments are not preserved by any of these conversions — parsing discards them, so a heavily annotated config loses its annotations. And YAML's older type coercion rules are the source of the notorious "Norway problem", where an unquoted NO is read as boolean false; quote values you mean as strings.
Related and equally local: JSON formatter and validator, .env to JSON converter, and CSV to JSON.
How to convert JSON, YAML and TOML offline
- 1
Pick the source and target formats.
- 2
Paste your config — conversion is live.
- 3
Copy the result from the output pane.
JSON ↔ YAML ↔ TOML — frequently asked questions
Are my config files uploaded to convert them?
No — parsing and conversion run with open-source libraries in your browser. Config files often contain credentials, which is exactly why they shouldn't touch upload-based converters.
Which conversions are supported?
Any direction between JSON, YAML, and TOML. The output updates live as you type.
Why does TOML sometimes refuse to convert?
TOML requires an object (table) at the top level — a bare array or scalar can't be represented, and null values have no TOML equivalent.