Numarly

JSON ↔ YAML Converter

Convert JSON to YAML or YAML to JSON instantly, with validation.

JSON → YAML

What Is the JSON ↔ YAML Converter?

JSON and YAML are both common data-serialization formats — JSON is compact and widely used in APIs, while YAML is more human-readable and common in configuration files. This tool converts between them in either direction, entirely in your browser.

How Is the JSON ↔ YAML Converter Calculated?

Converting JSON to YAML parses the JSON into a data structure, then re-serializes it using YAML's indentation-based syntax. Converting YAML to JSON does the reverse — YAML's parser resolves indentation, keys, and value types into the same underlying structure, which is then serialized as JSON. Since both formats represent the same underlying data types (objects, arrays, strings, numbers, booleans), a valid document in one converts cleanly to the other.

JSON ↔ YAML Converter Example

The JSON {"name":"Numarly","active":true} converts to the YAML:
name: Numarly
active: true

How to Use the JSON ↔ YAML Converter

Step 1

Choose a direction (JSON → YAML or YAML → JSON), or use Swap to flip it.

Step 2

Paste your input on the left.

Step 3

Copy the converted result from the right.

Benefits

  • Converts in either direction from a single tool.
  • Validates input and shows a clear error message if something doesn't parse.
  • Processes everything locally in your browser — nothing is uploaded anywhere.

Common JSON ↔ YAML Converter Scenarios

Scenario 1

Converting a JSON API response into YAML for a config file (like Kubernetes or Docker Compose).

Scenario 2

Converting a YAML config file into JSON for use in a script or API request.

Scenario 3

Quickly checking whether a YAML file is valid before using it.

Understanding Your Result

The output panel shows your input re-expressed in the other format, preserving the same underlying data — the same keys, values, and structure, just written with different syntax. If your input has a syntax error, the output stays empty and the specific parsing error is shown instead.

Tips

  • YAML is sensitive to indentation — use consistent spacing (not tabs) when editing YAML by hand.
  • Use Swap to convert a result back, which is handy for round-tripping and checking a conversion.
  • Comments in YAML aren't representable in JSON, so converting YAML with comments to JSON will drop them.

Common Mistakes

  • Mixing tabs and spaces in YAML input, which is invalid and causes a parse error.
  • Forgetting that JSON requires double quotes around keys and string values, unlike YAML which often doesn't need them.
  • Assuming comments survive a YAML → JSON → YAML round trip — JSON has no comment syntax, so they're lost on the way through.

Frequently Asked Questions

Is my data sent anywhere?

No — all parsing and conversion happens locally in your browser using JavaScript; nothing is uploaded to a server.

Does this preserve comments in my YAML?

No — JSON has no comment syntax, so converting YAML with comments to JSON will drop them; converting back to YAML afterward won't restore them either.

Why is my YAML input showing an error?

YAML is indentation-sensitive — a common cause is mixing tabs and spaces, or inconsistent indentation between sibling keys; check that indentation is consistent throughout.

Can this handle nested objects and arrays?

Yes — both JSON and YAML support arbitrarily nested objects and arrays, and this tool converts nested structures correctly in either direction.

What YAML features aren't supported in JSON?

Comments, multi-document files (separated by ---), and YAML anchors/aliases (for reusing values) don't have a JSON equivalent and won't convert directly.

Does YAML require quotes around strings like JSON does?

No — YAML strings are often written without quotes, though quotes are still valid and sometimes necessary (for strings that could be misread as numbers, booleans, or null).

Is YAML a superset of JSON?

Largely, yes — most valid JSON is also valid YAML, though YAML adds additional syntax (like unquoted strings, comments, and anchors) that JSON doesn't support.

Can I convert a JSON array at the top level, not just an object?

Yes — both a top-level JSON array and a top-level YAML list convert correctly, not just object/mapping structures.

What's a common use case for converting between these formats?

Configuration files for tools like Kubernetes, Docker Compose, and CI/CD pipelines are commonly written in YAML, while APIs typically exchange JSON — this tool bridges the two when working across both.

Important Information

Conversion happens entirely in your browser. YAML-specific features like comments and anchors are not preserved when converting to JSON.

Last updated: August 9, 2026