JSON to YAML Converter

When JSON to YAML makes sense

JSON is what APIs and programs emit; YAML is what people maintain by hand. You usually convert in this direction when data produced by a tool has to become a config file someone will edit:

• kubectl get -o json output that should become a manifest in Git.
• An API response you want to paste into a Helm values file or a GitHub Actions workflow.
• A package.json-style settings object being moved to a YAML-based tool.

Because every JSON document is also valid YAML, the goal here is not validity but readability: indentation instead of braces, no quotes where they are not needed, and multi-line text shown as real lines.

How the output is written

The JSON is parsed losslessly and printed as block-style YAML with two-space indentation:

• Objects become mappings and arrays become - sequences, in the original key order.
• Empty objects and arrays are written inline as {} and [].
• Strings containing line breaks are written as literal blocks (|), so a certificate or a SQL query stays readable.
• Numbers keep the exact digits from the source. A 20-digit ID is not rounded, though 1.50 is written as 1.5.
• Long lines are never folded, so values are not split across lines.

Anchors and aliases are never generated: if the same object appears twice in the JSON, it is written out twice.

Quoting that protects your data

The trickiest part of YAML is that unquoted text can silently change type. A value that is a harmless string in JSON may be read as something else by a YAML parser, especially an older YAML 1.1 one such as PyYAML, Ruby’s Psych or Ansible.

To avoid that, the converter quotes any string a YAML 1.1 or 1.2 reader could mistype:

• "NO", "on", "y" (booleans in YAML 1.1 — the Norway problem).
• "0755", "1.0", "1e3" (would become numbers).
• "null", "~" and "2024-01-01".
• Text containing : or #, or starting with an indicator such as @, *, &, ! or - .

Keys get the same treatment, which is why a key named n or on appears in quotes. Quoted output may look busier, but it reads back as exactly the JSON you started with.

Options and limits

This converter has no settings of its own. JSON contains no comments, so there is nothing to carry across; add comments to the YAML afterwards if you need them.

Invalid JSON is not guessed at. Trailing commas, single quotes or comments produce an error with a line and column; fix them in the JSON formatter, which can repair common mistakes, then convert. Duplicate keys are allowed through with a warning, and the last value wins, as in JSON.parse.

Round trips

Converting back with YAML to JSON returns the same data: the same keys in the same order, the same numbers and the same strings. Only formatting differs. That makes this pair handy for reviewing a JSON payload as YAML and then sending it on unchanged. Everything runs client-side, so you can do it with production data.

Examples

{
  "apiVersion": "apps/v1",
  "kind": "Deployment",
  "metadata": { "name": "checkout", "labels": { "app": "checkout" } },
  "spec": {
    "replicas": 3,
    "template": {
      "spec": {
        "containers": [
          { "name": "app", "image": "acme/checkout:1.8.2", "ports": [{ "containerPort": 8080 }] }
        ]
      }
    }
  }
}

apiVersion: apps/v1
kind: Deployment
metadata:
  name: checkout
  labels:
    app: checkout
spec:
  replicas: 3
  template:
    spec:
      containers:
        - name: app
          image: acme/checkout:1.8.2
          ports:
            - containerPort: 8080

{
  "country": "NO",
  "fileMode": "0755",
  "version": "1.10",
  "enabled": "on",
  "released": "2024-01-01",
  "nothing": null
}

country: "NO"
fileMode: "0755"
version: "1.10"
enabled: "on"
released: "2024-01-01"
nothing: null

{
  "name": "nightly-report",
  "query": "SELECT id, total\nFROM orders\nWHERE paid = true\n",
  "notify": ["ops@example.com"]
}

name: nightly-report
query: |
  SELECT id, total
  FROM orders
  WHERE paid = true
notify:
  - ops@example.com

Common errors and how to fix them

Related tools

• YAML to JSON
• JSON formatter
• YAML formatter
• JSON to TOML
• json validator
• json vs yaml
• yaml norway problem