How do I convert a YAML file to JSON?

Open the file, copy its contents, and paste them into the Source box above. The tool auto-detects YAML, converts it to JSON instantly, and gives you Copy and Download (.json) buttons. Nothing is uploaded — the parsing happens in your browser, so it works offline and is safe for private config.

Yes. JSON is a strict subset of YAML 1.2, so any valid JSON document is also valid YAML. That is why the converter's auto-detect checks the first character: a leading { or [ that parses as JSON is treated as JSON→YAML; anything else is parsed as YAML→JSON. You can override the guess with the direction toggle.

How do YAML anchors and aliases convert to JSON?

JSON has no reference mechanism, so anchors (&name) and aliases (*name) are materialised: the referenced subtree is duplicated wherever the alias appears. Merge keys (<<: *name) are resolved into the surrounding object before output. The result is plain JSON with no shared references.

How are YAML multi-document files converted to JSON?

A YAML stream can hold several documents separated by ---. Because JSON has no document-separator concept, the converter collects every document and emits a JSON array, one element per document. A single-document file converts to a plain object or value, not a one-element array.

What is the difference between YAML and JSON?

Both describe the same data shapes (objects, arrays, strings, numbers, booleans, null). YAML is indentation-based, allows comments, anchors and multiple documents, and is common for config (Kubernetes, Docker Compose, GitHub Actions). JSON uses braces and brackets, has no comments or references, and is the default for APIs and package files.

Why does .inf or .nan turn into null?

YAML's Core Schema allows .inf, -.inf and .nan as float values, but JSON (RFC 8259) has no way to represent infinity or not-a-number. JSON.stringify emits null for them. The converter detects this, still produces output, and flags it as a lossy conversion with the exact path so you know what changed.

Are comments preserved when converting YAML to JSON?

No. JSON has no comment syntax, so YAML # comments are dropped during conversion and cannot be recovered on the way back. This is a known limitation of the formats, not the tool. If you need comments, keep the YAML as your source of truth and treat the JSON as a generated artifact.

Is my data uploaded anywhere?

No. The conversion runs entirely client-side using the js-yaml parser bundled into the page. No network request is made when you convert, so you can paste Kubernetes secrets, API payloads or any sensitive config without it leaving your device. Open your browser's Network tab to verify.

Developer · Data formats

YAML to JSON Converter (bidirectional)

Convert YAML to JSON and JSON to YAML in one place. Auto-detects the direction, expands anchors and aliases, handles multi-document streams, pinpoints parse errors by line, and verifies every conversion with a round-trip check. Runs fully in your browser — nothing is uploaded.

By Induwara Ashinsana— Executive Director, Ryzera TechnologiesUpdated Jun 25, 2026

YAML ⇄ JSON Converter

Round-trip verified

Direction

Detected: YAML → JSON

Indent

Try a sample

Sourcepaste YAML or JSON

JSON output

{
  "defaults": {
    "retries": 3,
    "timeout": 30
  },
  "production": {
    "retries": 3,
    "timeout": 60,
    "enabled": true,
    "region": null,
    "hosts": [
      "api.induwara.lk",
      "cdn.induwara.lk"
    ]
  }
}

Valid. Output re-parses to an identical structure (round-trip verified).

Documents

Keys

Nodes

Spec-driven (YAML 1.2.2 + RFC 8259) · 100% client-side · no upload

How it works

The converter is a deterministic parse-then-serialize pipeline. There are no heuristics and no network calls: the YAML 1.2.2 Core Schema fixes how every scalar resolves, and RFC 8259 fixes the JSON it emits, so the same input always produces the same output.

Detect direction. In Auto mode the tool checks the first non-whitespace character. A leading { or [ that also parses as JSON means you pasted JSON and want YAML. Everything else is treated as YAML. Because JSON is a strict subset of YAML 1.2, a YAML parser accepts both — the first-character check disambiguates your intent. You can override it with the toggle.
YAML → JSON. The input is parsed with loadAll so multi-document streams (separated by ---) are captured. Scalars resolve per the Core Schema: null/~/empty become JSON null, true/false become booleans, decimal/hex/octal integers and floats become numbers, and anything else is a string. Anchors and aliases are expanded and merge keys (<<) are resolved, because JSON has no reference mechanism. The structure is serialized with JSON.stringify at your chosen indent.
JSON → YAML. The input is parsed with JSON.parse and re-emitted as YAML in block style (or inline flow style if you prefer), with key order preserved unless you turn on sorting.
Validate. A parse failure never blanks the screen. The exception is caught and the first error is shown with its 1-based line and column plus a short snippet, so you can jump straight to it.
Round-trip check.The output is re-parsed and deep-compared against the original structure. Identical means "round-trip verified". If a construct cannot survive — for example .inf or .nan, which JSON renders as null — the result is marked lossy and the affected path is named.

This same engine (js-yaml on the YAML 1.2 schema) powers the worked examples below, which reproduce exactly in the live tool.

YAML ↔ JSON type mapping

Every conversion rule the tool applies, drawn from the YAML 1.2.2 Core Schema and RFC 8259. The * on the infinity/NaN row marks a construct JSON cannot represent.

YAML	JSON	Notes
null, ~, (empty)	null	All YAML null forms collapse to JSON null.
true / false	true / false	Boolean. Only the canonical lowercase forms in the Core Schema.
42, 0x2A, 0o52	42	Integers: decimal, hex (0x) and octal (0o) all resolve to a number.
3.14, 1e3	3.14, 1000	Floats keep their numeric value.
.inf, -.inf, .nan	null *	JSON has no Infinity/NaN — these become null and are flagged as lossy.
"text", text	"text"	Any non-resolving scalar is a string; JSON always quotes it.
- a\n- b (block) / [a, b] (flow)	[a, b]	Both block and flow sequences become a JSON array.
key: val / {key: val}	{"key": val}	Block and flow mappings become a JSON object.
&anchor / *alias	(expanded)	JSON has no references — aliases are materialised into duplicated subtrees.
<<: *anchor (merge)	(merged keys)	Merge keys are resolved into the surrounding object.
doc1\n---\ndoc2	[doc1, doc2]	A multi-document stream becomes a JSON array of documents.
# comment	(dropped)	JSON has no comments; they are not preserved.

Worked examples

YAML → JSON, with an anchor, merge key and null

YAML

defaults: &d
  retries: 3
  timeout: 30
prod:
  <<: *d
  timeout: 60
  enabled: true
  region: ~

JSON

{
  "defaults": { "retries": 3, "timeout": 30 },
  "prod": {
    "retries": 3,
    "timeout": 60,
    "enabled": true,
    "region": null
  }
}

&d defines the anchor { retries: 3, timeout: 30 }.
prod merges it with <<: *d, then overrides timeout to 60.
enabled: true stays a boolean; region: ~ resolves to null.
The anchor is expanded (JSON has no references).

JSON → YAML, nested object and array

JSON

{ "name": "induwara",
  "tags": ["seo", "tools"],
  "meta": { "live": true, "rank": null } }

YAML

name: induwara
tags:
  - seo
  - tools
meta:
  live: true
  rank: null

The object becomes a block mapping.
The array becomes a block sequence with - markers.
true stays boolean; null is emitted as null.
Round-trip: re-parsing the YAML returns the original object.

Lossy edge case — .inf in YAML

YAML

bandwidth: .inf
samples: 1000

JSON

{
  "bandwidth": null,
  "samples": 1000
}

.inf resolves to Infinity under the YAML Core Schema.
JSON (RFC 8259) cannot represent infinity, so it becomes null.
The tool still converts but marks the result lossy and names the path ($.bandwidth).
samples: 1000 converts cleanly as an integer.

Frequently asked questions

Sources & references

Conversion rules were last cross-checked against the YAML 1.2.2 spec and RFC 8259 on 2026-06-25. The tool uses the js-yaml parser on the YAML 1.2 Core/Default schema.

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Comments & feedback

Spotted a bug or want an improvement? Tell us — our team reviews every comment, and good ideas get built. Comments are public and anonymous.

Found a bug, edge case, or want to suggest an improvement?

Email me at [email protected] — most fixes ship within 24 hours.

How it works

YAML ↔ JSON type mapping

Worked examples

YAML → JSON, with an anchor, merge key and null

JSON → YAML, nested object and array

Lossy edge case — .inf in YAML

Frequently asked questions

How do I convert a YAML file to JSON?

Is JSON valid YAML?

How do YAML anchors and aliases convert to JSON?

How are YAML multi-document files converted to JSON?

What is the difference between YAML and JSON?

Why does .inf or .nan turn into null?

Are comments preserved when converting YAML to JSON?

Is my data uploaded anywhere?

Sources & references

Related tools

TOML ⇄ JSON Converter

Unix Timestamp Converter

JavaScript Playground

Comments & feedback