YAML to JSON and JSON to YAML Without Leaving the Browser
This YAML JSON converter handles both YAML to JSON and JSON to YAML conversion in the browser, which is exactly what you want when you're bouncing between config files, API fixtures, CI pipelines, and Kubernetes manifests. Paste one format, convert it, copy the result, move on.
The useful part is not the syntax swap by itself. It is being able to turn a YAML document like name: toolzy\nenabled: true into valid JSON such as { "name": "toolzy", "enabled": true }, or go the other direction when a tool expects YAML instead of JSON. For quick one-off transforms, a YAML to JSON converter online is faster than wiring up a script or remembering the right CLI flags.
Everything runs locally in your browser. Your input is parsed and converted on your machine, so you can inspect private config data, deployment manifests, or test payloads without sending them to a server.
Using it
Paste YAML or JSON into the input, choose the conversion direction, and run the conversion. Review the output for structure and types, then copy the result into your editor, API client, or config file.
If the input is invalid, fix the reported syntax issue first. YAML is especially sensitive to indentation, and JSON is strict about quotes, commas, and braces.
When this tool is actually useful
- Converting Kubernetes, Docker Compose, or GitHub Actions YAML into JSON for debugging or programmatic inspection
- Turning JSON API fixtures into YAML for human-readable config files or docs examples
- Checking how nested arrays and objects map between formats before committing a config change
- Migrating small config snippets between tools that accept only one format
- Verifying whether a hand-written YAML document parses to the JSON structure you expect
YAML vs JSON: same data model, different ergonomics
YAML and JSON both describe structured data: objects/maps, arrays/lists, strings, numbers, booleans, and nulls. JSON is stricter and easier for machines to parse consistently. YAML is more ergonomic for humans editing config by hand.
That is why you see JSON in APIs and serialized payloads, but YAML in files like docker-compose.yml, pnpm-workspace.yaml, or CI configs. A JSON to YAML conversion usually makes dense data easier to scan. A YAML to JSON conversion makes the same data easier to validate, diff programmatically, or feed into code.
What changes during conversion
The data structure is preserved when the input is valid and uses features both formats can represent cleanly. A YAML list like this:
services:
- name: api
port: 3000
- name: web
port: 4321
Converts to JSON like this:
{
"services": [
{ "name": "api", "port": 3000 },
{ "name": "web", "port": 4321 }
]
}
What does not reliably survive a round trip is presentation-level detail. YAML comments, anchor syntax, aliases, key ordering choices, quoting style, and formatting preferences are usually lost once the document is parsed into data and re-serialized. If you run YAML to JSON and then JSON to YAML, expect equivalent data, not byte-for-byte identical text.
YAML-native collection tags such as !!set and !!omap are not part of ordinary JSON data. This converter treats them as unsupported rather than guessing at a lossy shape, so you will see an error if the input contains values that do not map cleanly to JSON objects, arrays, scalars, or null.
YAML parsing rules that matter
Indentation is structure in YAML. Two spaces where four were expected can move a value into a different object or make the document invalid. JSON does not have that problem because braces and brackets carry the structure explicitly.
YAML also supports features JSON does not, including comments and anchors. For example, # deploy config is legal YAML but has no JSON equivalent. That is why a parsed YAML to JSON conversion drops comments, and why a round trip cannot restore them.
Troubleshooting
My YAML to JSON conversion fails on indentation — YAML uses indentation to define nesting. Check for mixed tabs and spaces, inconsistent indent width, or list items that are aligned under the wrong parent key.
My JSON to YAML output looks different from the original style I want — conversion preserves data, not formatting preferences. Quotes, line breaks, and key layout may change when the parsed data is serialized back to YAML.
Comments disappeared after converting YAML to JSON — JSON has no comment syntax, so YAML comments are dropped during parsing and cannot be reconstructed later.
Anchors or aliases did not survive the round trip — YAML anchors and aliases are YAML-specific syntax sugar. After parsing, the converter keeps the resolved data structure, not the original anchor notation.
A value changed type unexpectedly — YAML parsers may interpret bare values like true, false, null, 42, or 3.14 as booleans, null, or numbers. Quote them in YAML if you need them treated as strings.
My YAML uses !!set or !!omap — Those YAML-native collection tags do not have a clean JSON equivalent. Convert them to ordinary lists or mappings first, or expect the YAML-to-JSON path to report them as unsupported.