YAML to JSON Converter

What is YAML to JSON?

YAML (YAML Ain’t Markup Language) is the standard config format for modern DevOps — Kubernetes, Docker Compose, GitHub Actions, Ansible, dbt. JSON is the standard data format for APIs and programming. Converting YAML → JSON is needed when you want to consume config files in code, validate against JSON Schema, or integrate with JSON-only tools.

Common scenarios: parsing Helm values.yaml in CI scripts, validating Kubernetes manifests with JSON Schema validators, OpenAPI spec consumption (most tools require JSON), config file unit tests (easier to compare structured JSON), API request bodies from YAML templates.

Conversion example

# YAML
name: myapp
ports:
  - 80
  - 443
env:
  DEBUG: false
  PORT: 3000
# Comments are preserved during edit but
# stripped during YAML→JSON (JSON has no comments)

# JSON
{
  "name": "myapp",
  "ports": [80, 443],
  "env": { "DEBUG": false, "PORT": 3000 }
}

What’s lost in conversion

• Comments: JSON has no comment syntax — all # lines are stripped
• Anchors / aliases: &name / *name are inlined (data preserved, structure flattened)
• Multi-line string formatting: | and > styles become regular JSON strings with \n escapes
• Document separators: --- markers between multiple YAML docs are not represented in JSON (need to convert each separately)
• Tags: !!str, !!float explicit type tags become inferred JSON types

Watch out for type coercion

YAML’s permissive type inference can produce surprises that show up in JSON output:

• Booleans: NO, yes, off, on become true/false (Norway problem) — quote them as strings to preserve text
• Numbers: 1.0 becomes number 1.0; quote as “1.0” if you mean version string
• Octals: 0644 in YAML 1.1 becomes 420 decimal (file permissions trap)
• Null: empty values, null, ~, NULL all become JSON null
• Dates: ISO date strings may be parsed as Date objects; quote to keep as string

How to Use

1. Paste YAML data, or upload a .yaml / .yml file.
2. Click Convert.
3. Review the JSON — verify type coercions (especially for boolean-looking strings, version numbers).
4. Copy or download as .json.

Privacy: Conversion runs in your browser via js-yaml. No upload.

Why Configuration Ended Up in YAML

JSON is excellent for machines and irritating for humans editing configuration by hand: no comments, mandatory quotes, and a trailing comma breaks the whole file. YAML was designed to fix exactly that, which is why Kubernetes manifests, GitHub Actions workflows, Docker Compose files, and CI pipelines are all written in it.

YAML is a strict superset of JSON, so every valid JSON document is already valid YAML. The conversion in this direction is therefore lossless in structure — the only thing that disappears is what JSON has no way to represent.

What Is Lost, and the Famous Gotchas

Comments. YAML’s single biggest advantage over JSON, and JSON has nowhere to put them. Expect every explanatory comment to vanish.

Anchors and aliases. YAML can define a block once and reference it repeatedly. Those references are resolved and inlined during conversion, so the data is preserved but the deduplication is not.

The Norway problem. In older YAML versions, the unquoted value no parses as boolean false — which famously turned the country code for Norway into false in a lot of configuration files. The same applies to yes, on, and off. Quoting such values is the fix.

Sexagesimal numbers. Older YAML treats 22:30 as a base-60 number rather than a time string. Another argument for quoting anything that is not obviously a number.

Indentation with tabs. YAML forbids tabs for indentation entirely, which produces confusing errors in editors configured to insert them.

FAQ