How are YAML anchors and aliases handled?

They are fully expanded. An alias (*ref) is replaced with a deep copy of the value its anchor (&ref) points to, because JSON cannot represent shared references. Your output is self-contained JSON with the referenced data inlined at every use site.

Will unquoted values like yes, no or on become booleans?

The converter follows the YAML 1.2 core schema, where only true and false are booleans. Legacy YAML 1.1 keywords such as yes, no, on and off are treated as plain strings, which avoids the classic 'Norway problem' where the country code NO turned into false.

Is anything sent to a server?

No. All parsing and conversion happen locally in your browser. Your YAML never leaves your machine, so it's safe to convert configs that contain sensitive hostnames or settings.

YAML to JSON Converter

Stable

Parse any YAML config into strict, valid JSON your code can consume.

Everything is processed locally in your browser

About YAML to JSON Converter

Convert YAML into strict, standards-compliant JSON without leaving your browser. This YAML to JSON converter resolves anchors and aliases, honors YAML's native scalar types, and produces JSON that parses cleanly in any language. It's the fastest way to feed a hand-written config or CI file into a program, a JSON schema validator, or an API that only speaks JSON.

Features

Fully resolves anchors (&) and aliases (*) into concrete JSON values
Maps YAML scalars - numbers, booleans, null and dates - to correct JSON types
Supports multi-document YAML and flow-style collections
Reports the exact line and column of syntax errors before converting
Optional pretty-printed or minified JSON output
Handles nested mappings and sequences at any depth without data loss

How to use YAML to JSON Converter

1
Paste your YAML
Paste a YAML document - a config file, manifest, or CI pipeline. Indentation and comments are parsed exactly as YAML intends.
2
Convert to JSON
The parser resolves anchors and types, then serializes the result as JSON. Errors are surfaced with line numbers if the YAML is invalid.
3
Copy the JSON
Grab the pretty or minified JSON output and paste it straight into your code, tests, or an API request body.

Examples

Service config to JSON

YAML mappings and sequences become JSON objects and arrays.

Input

server:
  host: 0.0.0.0
  port: 8080
  tls: true
features:
  - search
  - export

Output

{
  "server": {
    "host": "0.0.0.0",
    "port": 8080,
    "tls": true
  },
  "features": ["search", "export"]
}

How YAML to JSON conversion works

This direction can lose things, because YAML is the larger format

Converting JSON to YAML is lossless, because YAML is a superset. Coming back the other way narrows the data model, and several YAML features have no JSON equivalent at all.

Comments are the first casualty and usually the most significant. Everything after `#` is metadata for humans, and the JSON data model has nowhere to store it. If the YAML file was your documented source of truth, keep it - the JSON is a build artefact, not a replacement.

Anchors and aliases are resolved rather than preserved. An anchored block referenced in five places becomes five full copies in the JSON, since JSON cannot express a reference. The data is correct and the document is larger. Non-string mapping keys are the third gap: YAML permits any type as a key, and JSON requires strings, so a numeric or boolean key has to be coerced.

Where the type surprises come from

Everything ambiguous about YAML's type inference lands in the converted JSON, which makes this conversion a good way to discover problems you did not know your config had. An unquoted `yes` arrives as `true`. An unquoted `1.10` arrives as `1.1`. A value like `0755` may arrive as `493` if the parser reads it as octal.

None of these are conversion bugs - the YAML parser made those decisions, and any tool reading that file would have made the same ones. Seeing the JSON output is simply the first time the interpretation becomes visible, because JSON states types explicitly rather than inferring them.

So if a converted value looks wrong, the fix belongs in the YAML: quote it. That fixes the file for every consumer, not just for this conversion.

Multi-document files and other structural differences

A YAML file can contain several documents separated by `---`, which is extremely common in Kubernetes manifests where one file describes a Deployment, a Service and a ConfigMap. JSON has no equivalent - one file is one value.

The usual resolutions are to convert each document separately, or to wrap them in a JSON array. An array is convenient for programmatic processing but is not what a tool expecting individual resources will accept, so which one is right depends on the consumer.

Empty values are the other thing worth knowing. In YAML, a key with nothing after the colon is null, so `key:` on its own becomes `"key": null` rather than an empty string. That trips people up when a config value was left blank intentionally.

Reference

YAML features and what happens to them

YAML feature	In the JSON output	Impact
# comments	Removed	Keep the YAML as your source of truth
&anchor / *alias	Expanded inline	Correct data, larger document
--- separators	Not representable	Convert separately or wrap in an array
\| block scalar	String with \n escapes	Content preserved, formatting flattened
> folded scalar	String with spaces	Newlines become spaces, by definition
Non-string keys	Coerced to strings	JSON keys must be strings
key: (empty)	null	Not an empty string
yes / no	true / false	Quote in the YAML to keep them strings

Which tool should you use?

These tasks overlap. Here is how to pick the right one for what you are actually doing.

You need to feed a YAML config to something that only reads JSON: This is the standard case, and the conversion is reliable for data.
You want to check how a parser interprets your YAML: Converting is an effective diagnostic. JSON states types explicitly, so inference surprises become visible.
You are converting the other direction: The JSON to YAML tool is lossless, since YAML is the superset.
The YAML holds multiple documents: Split on `---` and convert each separately, unless the consumer is happy with a JSON array.

Use cases

Load a hand-edited YAML config into a program that only reads JSON
Validate a YAML manifest against a JSON Schema
Convert docker-compose.yml into JSON for programmatic inspection
Turn CI pipeline YAML into JSON for diffing or auditing
Prepare YAML test fixtures as JSON request payloads

Troubleshooting common errors

Comments are missing from the JSON

Why: JSON has no comment syntax, so there is nowhere to put them.

Fix: Treat the YAML as the source of truth and the JSON as generated output. Do not hand-edit the JSON.

"yes" became true

Why: The YAML parser applied YAML 1.1 boolean rules to an unquoted scalar.

Fix: Quote it in the YAML file. Every consumer of that file has been reading it as a boolean, not just this converter.

The output is much larger than the YAML input

Why: Anchors were expanded into full copies at each reference site.

Fix: Expected and unavoidable - JSON cannot express references. The data is equivalent.

Conversion fails on a Kubernetes manifest

Why: The file contains multiple documents separated by `---`, which is not a single JSON value.

Fix: Convert each document on its own, or wrap them in a JSON array if the consumer accepts that.

An empty config value became null instead of ""

Why: In YAML, a key with no value is null by definition.

Fix: Write `key: ""` in the YAML if you specifically want an empty string.

Limitations

What this tool deliberately does not do, so you know when to reach for something else.

Comments, anchors and block-scalar formatting cannot survive, since JSON has no equivalents.
Multi-document YAML files are not representable as a single JSON value.
Non-string mapping keys are coerced to strings.
Type inference decisions made by the YAML parser are carried through and cannot be reversed here.
Very large files are limited by browser memory, as the whole document is parsed at once.

Frequently asked questions

JSON to YAML Converter

Turn JSON into clean, readable YAML for configs, pipelines and manifests.

Online JSON Formatter & Validator

Pretty-print JSON with configurable indentation and instant validation.

JSON Validator

Validate JSON syntax and pinpoint the exact line and column of any error.

CSV to JSON Converter

Parse CSV into a clean array of typed JSON objects, header-aware.

Learn more

How to Convert YAML to JSON Without Breaking Your ConfigYAML is friendlier to write, but most tools and APIs still expect JSON. Here is how the conversion really works, what gets lost, and how to do it safely in your browser.