JSON to YAML converter

Each JSON construct has one natural YAML form. The converter writes block style (indentation, no brackets) because that is what config files use:

• Indent 2 or 4 spaces. Two is the convention for Kubernetes, Docker Compose and GitHub Actions. YAML never allows tabs.
• Quotes only when needed, single or double. Double quotes allow escapes like \n and é; single quotes take text literally, with '' for a single quote inside. Keys are left unquoted where possible.
• YAML 1.1 safe. YAML 1.2 reads no as the text "no", but YAML 1.1 parsers such as PyYAML read it as false. Keeping this on quotes such values so every parser gets the string you meant. This is how Norway's country code NO turns into false.
• Indent lists. Off gives the style kubectl get -o yaml prints, with - item at the same column as its key.
• Sort keys. Alphabetical order makes two files easy to diff. Off keeps the JSON order, which is usually the order people expect to read (apiVersion, kind, metadata, spec).
• Array → separate documents. A top-level array becomes several YAML documents separated by ---, the format kubectl apply -f accepts for many resources in one file.

Command line with yq (v4):

yq -p=json config.json > config.yaml
cat config.json | yq -p=json -I=4     # 4-space indent

Python with PyYAML. safe_dump sorts keys unless you pass sort_keys=False:

import json, yaml

with open("config.json", encoding="utf-8") as f:
    data = json.load(f)
print(yaml.safe_dump(data, sort_keys=False, allow_unicode=True))

JavaScript / Node.js with the yaml package:

import { stringify } from 'yaml';

const yaml = stringify(JSON.parse(jsonText), { indent: 2 });

Go with sigs.k8s.io/yaml:

import "sigs.k8s.io/yaml"

y, err := yaml.JSONToYAML(jsonBytes)

Kubernetes can print any live object as YAML directly: kubectl get deployment web -o yaml.

YAML 1.2 was written so that JSON is a subset of it: a YAML 1.2 parser reads JSON as is. To go the other way, use the YAML to JSON converter, and check the result with the YAML validator. If the JSON itself has errors, the JSON formatter shows and repairs them. More tooling for configs and deploys: DevOps tools on DevHunt.