JSON to YAML Converter

The JSON to YAML Converter translates data between JSON (JavaScript Object Notation) and YAML (YAML Ain't Markup Language) — the two most popular structured data formats in modern development. Paste JSON from an API response or config file and get clean, properly-indented YAML output. Or reverse: paste YAML from a Kubernetes manifest, GitHub Actions workflow, Docker Compose file, or Ansible playbook and get the equivalent JSON. Handles any depth of nesting, arrays, boolean/null values, multi-line strings, and special YAML features like anchors and references.

JSON is the dominant format for APIs (lightweight, easy to parse). YAML is the preferred format for configuration files (human-readable, supports comments, less syntactic noise). Many modern tools use YAML configs that reference structured data originally in JSON: Kubernetes manifests, Helm charts, Docker Compose, GitHub Actions workflows, CircleCI, GitLab CI, Ansible playbooks, Jekyll/Hugo front matter, OpenAPI/Swagger specs. Being able to convert cleanly between the two is essential. This tool does it instantly in your browser — configs stay private.

JSON and YAML both represent structured data — objects (maps), arrays (lists), and scalar values (strings, numbers, booleans, null) — but with different syntax optimized for different use cases.

JSON (RFC 8259, 2017):

- Strict syntax, no comments.
- Quotes required around all keys and string values.
- Commas between elements, required.
- Compact and unambiguous; ideal for machine-to-machine.

YAML (yaml.org spec 1.2.2, 2021):

- Indentation-based (like Python).
- Quotes optional for simple strings.
- Supports comments (#), anchors (&name), aliases (*name), and multi-line strings.
- Human-readable and expressive; ideal for config files.

Conversion rules:

- JSON object { "a": 1 } → YAML a: 1
- JSON array [1, 2, 3] → YAML - 1\\n- 2\\n- 3
- JSON string "hello" → YAML hello (or "hello" if ambiguous)
- JSON boolean true/false → YAML true/false
- JSON null → YAML null or ~ or empty
- JSON number 3.14 → YAML 3.14
- Nested JSON objects → YAML nested indentation

YAML quirks that don't round-trip cleanly:

- The Norway problem: YAML 1.1 parses NO, no, off, false as boolean false. Country code for Norway (NO) becomes false! YAML 1.2 fixed this, but many parsers still use 1.1 semantics.
- Unquoted numbers: 3:30 is interpreted as time (3 hours, 30 minutes). 08 and 09 are invalid octal; 0.0 is 0. Version numbers like 1.0 become floats.
- Multi-line strings: Multiple syntaxes (|, >, "...", '...') with subtle differences.
- Anchors and aliases: &anchor_name and *anchor_name have no JSON equivalent — conversion flattens them.

Recommended defaults:

- Always use YAML 1.2 compatible tooling.
- Use double quotes around strings that look like booleans, numbers, dates, or special values.
- Use version: "1.0" not version: 1.0.
- Avoid anchors and references when converting to JSON (they'll be expanded).

Block vs flow style:

YAML supports two styles:

Block (default, human-readable):
``yaml
user:
name: Jane Doe
roles:
- admin
- editor
``

Flow (JSON-like, compact):
``yaml
user: {name: "Jane Doe", roles: ["admin", "editor"]}
``

Flow style is essentially JSON with YAML quirks. Block style is preferred for config files.

JSON vs YAML file sizes:

- Same data: YAML typically ~10-20% smaller (no quotes, no braces, fewer commas).
- With comments: YAML supports them, JSON doesn't. If you need comments, YAML wins.

JSON vs YAML: JSON is strict, compact, machine-first (ideal for APIs). YAML is readable, human-first (ideal for configs). Both represent the same data structures. API responses use JSON. Configuration files use YAML.

JSON vs TOML: TOML (used by Cargo, poetry, Hugo) is another config format — simpler than YAML, more explicit, no significant whitespace. Good for simple configs. Less widespread than YAML.

YAML 1.1 vs YAML 1.2: 1.2 fixes the Norway problem (booleans require true/false, not yes/no), removes octal ambiguity, and modernizes the spec. 1.1 is still common in tooling. Check which your parser uses.

YAML vs JSON5: JSON5 is JSON with YAML-like conveniences (comments, trailing commas, unquoted keys). Simpler than YAML but less widespread.

YAML vs XML: XML is older, more verbose, and used for enterprise (SOAP, RSS, Office docs). YAML is a modern, lighter alternative. Most new projects use YAML or JSON, not XML.

YAML vs HCL: HCL (Terraform's language) is a config language designed specifically for infrastructure-as-code. More expressive than YAML for complex logic. YAML is simpler and more widespread.