How do I convert YAML to JSON online?

Paste YAML on the left. The converter parses it with js-yaml (the de-facto standard YAML parser) and serializes the parsed object as JSON on the right. Click the swap arrow to flip direction (JSON to YAML). Pure browser — nothing uploads.

What's the difference between YAML and JSON?

Both encode the same data shapes (objects, arrays, primitives). YAML is whitespace-significant and human-friendly with comments; JSON is brace-and-bracket and machine-friendly. Most APIs ingest JSON. OpenAPI specs are commonly authored in YAML and converted to JSON for tooling that doesn't speak YAML natively.

Can I convert OpenAPI YAML to JSON?

Yes — that's a primary use case. OpenAPI specs in YAML convert to identical-shape JSON. Most spec tools (Swagger UI, Redoc, Specway) accept both. The conversion is lossless as long as your YAML doesn't use anchors/aliases that point to circular references — those don't exist in JSON and will fail.

Why does my YAML fail to convert?

Common causes: (1) tabs instead of spaces (YAML rejects tabs for indentation), (2) inconsistent indent depth in the same block, (3) unescaped special characters in unquoted strings (colons, hashes, brackets), (4) duplicate keys at the same level. The error message names the line — fix that one and re-run.

Why does my JSON-to-YAML output use anchors?

js-yaml emits anchors (&id, *id) when it detects the same object referenced multiple times in your input — a common pattern in JSON when you JSON.parse(JSON.stringify(...)) wasn't used to deep-clone. Anchors are valid YAML, but if you don't want them, deep-clone your input first.

Does this handle multi-document YAML?

Single-document only — the most common case. Multi-document YAML (separated by `---`) doesn't have a clean JSON equivalent because JSON has no top-level concatenation. Convert each document separately, or output a JSON array of documents using a streaming parser.

What's the YAML version this supports?

YAML 1.2 (the latest stable). Specifically js-yaml's safe schema, which excludes the legacy implicit type tags from YAML 1.1 (no, on, off as booleans). If your YAML relies on those, upgrade — modern parsers are dropping them as security and predictability hazards.

How do I convert YAML to JSON online?

Paste YAML on the left. The converter parses it with js-yaml (the de-facto standard YAML parser) and serializes the parsed object as JSON on the right. Click the swap arrow to flip direction (JSON to YAML). Pure browser — nothing uploads.

What's the difference between YAML and JSON?

Both encode the same data shapes (objects, arrays, primitives). YAML is whitespace-significant and human-friendly with comments; JSON is brace-and-bracket and machine-friendly. Most APIs ingest JSON. OpenAPI specs are commonly authored in YAML and converted to JSON for tooling that doesn't speak YAML natively.

Can I convert OpenAPI YAML to JSON?

Yes — that's a primary use case. OpenAPI specs in YAML convert to identical-shape JSON. Most spec tools (Swagger UI, Redoc, Specway) accept both. The conversion is lossless as long as your YAML doesn't use anchors/aliases that point to circular references — those don't exist in JSON and will fail.

Why does my YAML fail to convert?

Common causes: (1) tabs instead of spaces (YAML rejects tabs for indentation), (2) inconsistent indent depth in the same block, (3) unescaped special characters in unquoted strings (colons, hashes, brackets), (4) duplicate keys at the same level. The error message names the line — fix that one and re-run.

Why does my JSON-to-YAML output use anchors?

js-yaml emits anchors (&id, *id) when it detects the same object referenced multiple times in your input — a common pattern in JSON when you JSON.parse(JSON.stringify(...)) wasn't used to deep-clone. Anchors are valid YAML, but if you don't want them, deep-clone your input first.

Does this handle multi-document YAML?

Single-document only — the most common case. Multi-document YAML (separated by `---`) doesn't have a clean JSON equivalent because JSON has no top-level concatenation. Convert each document separately, or output a JSON array of documents using a streaming parser.

What's the YAML version this supports?

YAML 1.2 (the latest stable). Specifically js-yaml's safe schema, which excludes the legacy implicit type tags from YAML 1.1 (no, on, off as booleans). If your YAML relies on those, upgrade — modern parsers are dropping them as security and predictability hazards.

Free Tool

YAML ↔ JSON Converter (2026)

Bidirectional YAML/JSON converter. Paste YAML to get JSON, or JSON to get YAML — swap direction with one click. Built on js-yaml (YAML 1.2). Runs entirely in your browser.

YAMLJSON

YAML input

JSON output

{
  "openapi": "3.1.0",
  "info": {
    "title": "Specway Tools API",
    "version": "1.0.0"
  },
  "paths": {
    "/tools": {
      "get": {
        "summary": "List tools",
        "responses": {
          "200": {
            "description": "OK"
          }
        }
      }
    }
  }
}

YAML vs JSON: when to use each

YAML is human-friendly: indentation-based, comment-supporting, terse. Great for config files and hand-edited specs (CI configs, OpenAPI, Kubernetes manifests).

JSON is machine-friendly: braces and brackets, strict, universal parser support. Required by most APIs, almost all programming languages, and every browser.

You usually author in YAML and ship in JSON. This tool is the bridge.

Lossless round-trip caveats

YAML anchors and aliases (&ref / *ref) get expanded when converting to JSON. Round-tripping back to YAML won't recreate them — the data is identical, the structure is just inlined.
YAML comments don't exist in JSON. Convert YAML→JSON→YAML and you'll lose all comments.
YAML multi-document streams (separated by ---) have no JSON equivalent — convert each document separately.
Number precision: very large integers (> 2^53) get rounded. JSON doesn't distinguish int vs float cleanly. If you need bigint precision, send strings.

OpenAPI authoring workflow

Most OpenAPI specs are authored in YAML for the comment support and readability advantage. CI then runs validation on both YAML and JSON representations, and the deployed docs ship JSON because most tooling (and Specway) ingests both.

If your repo has only YAML, this tool is the quick fix when a tool wants JSON. For automated pipelines, use js-yaml in Node or PyYAML in Python directly.

Ship API docs that stay this clean

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Related tools

JSON Formatter

Pretty-print or minify the JSON output.

JSON Validator

Validate JSON syntax with line/column errors.

OpenAPI Validator

Validate the converted OpenAPI spec.

OpenAPI Viewer

Render the spec as interactive docs.

Frequently asked questions