Why convert YAML to JSON?

To process YAML configs in JavaScript code, send them to APIs that only accept JSON, or inspect them with tools that understand JSON but not YAML.

What does this converter support?

The most common syntax: scalars (strings, numbers, booleans, null), hyphen-prefixed lists, nested maps, and # comments. It does not support anchors/aliases or custom tags.

Why does YAML use indentation?

YAML was designed to be human-readable. Indentation replaces braces and brackets, reducing visual noise. But it also makes YAML sensitive to spacing errors — one stray space breaks everything.

YAML to JSON — Free Converter

YAML: human-readable, parser-strict

YAML (recursive acronym for "YAML Ain't Markup Language") was born in 2001 as an XML alternative for configs. Big idea: use indentation instead of braces or brackets to denote hierarchy. The result reads like a bullet list rather than code. That's why Kubernetes, Docker Compose, GitHub Actions, GitLab CI, Ansible and most modern devops tools use it.

Why convert to JSON

JavaScript processing. Browsers parse JSON natively; YAML needs an external library of several KB.
APIs. Almost every REST API speaks JSON. If your config is YAML, you must convert.
Validation with existing tools. JSON Schema is mature; YAML equivalents are less common.
Version diffs. YAML diffs can be misleading because of indentation; minified JSON diffs are always clear.

Typical use cases

Inspecting a Kubernetes manifest. Convert to JSON to view it in an API tool or run jq over it.
Migrating config to a JSON-only system. Plenty of legacy still expects JSON.
Test snapshots. Snapshotting structures as JSON is easier in testing.
Posting to a REST endpoint. Some APIs accept YAML but most don't.

Limitations of this converter

It supports the most common syntax that covers 95% of cases: scalars (strings, numbers, booleans, null), hyphen-prefixed lists, nested maps with colons, and # comments. It does NOT support advanced YAML features like anchors (&), aliases (*), custom tags (!!str), multi-document streams (---) or mixed flow style. For those cases, use a full library like js-yaml.

Common YAML traps

Tab indentation. YAML allows only spaces. Mixing tabs and spaces breaks the parser.
Accidental booleans. "yes", "no", "on", "off", "y", "n" are parsed as booleans. To keep the literal string, quote it.
Numbers that look like strings. "012" is parsed as octal in YAML 1.1 — quote it.
The "Norway problem." Norway's ISO code is "NO" and YAML turns it into false. Famous saga: countries: [NO, NL] ends up as [false, "NL"].

YAML vs JSON: which to use

For config a human will hand-edit, YAML is more readable. For data flowing between machines, JSON is stricter and faster to parse. Good practice: write configs in YAML but compile to JSON at build time and serve JSON in production. Cuts surprises from ambiguous types and improves parser performance.

Security tips

YAML has a complicated security history: it can execute arbitrary code via tags if the parser supports it (CVEs in Ruby psych, Python pyyaml). When parsing untrusted YAML, use a "safe" loader that only allows basic types. This converter never executes code under any circumstances.

YAML to JSON