YAML to JSON

The YAML to JSON Converter turns human-friendly YAML documents into exact JSON equivalents in your browser. YAML powers Kubernetes manifests, Docker Compose files, GitHub Actions workflows, GitLab CI pipelines, Ansible playbooks, CloudFormation templates, OpenAPI specs, Helm charts, and most modern CI/CD configuration. JSON is the universal interchange format for APIs, NoSQL databases, configuration parsers, and every JavaScript tool in existence. Converting between them is a daily task for backend engineers, DevOps teams, and anyone who lives inside cloud-native infrastructure.

This tool understands every corner of the YAML 1.2 specification, not just the simple key-value subset. Anchors and aliases are resolved so the shared values in your docker-compose file expand into real JSON branches. Block scalars with folded or literal indicators (> and |) preserve their whitespace correctly. Flow style (JSON-like inline syntax inside YAML) is parsed indistinguishably from block style. Typed tags like !!int, !!timestamp, and !!binary are mapped to sensible JSON representations. And because YAML is notoriously picky about indentation and quoting, the converter returns exact line and column numbers whenever a document is invalid, so you can fix the problem and retry in seconds.

YAML is a strict superset of JSON in theory — every valid JSON document is also valid YAML — but the reverse mapping has several subtleties that matter when you convert in bulk.

First, types. YAML infers types from unquoted scalars: true, false, null, 42, 3.14, and ISO timestamps all become typed values. JSON has no date or binary type, so YAML timestamps become ISO-8601 strings and YAML !!binary becomes base64-encoded strings by convention. If you need the original bytes, you decode from base64 on the receiving side.

Second, anchors and aliases. A YAML document can define a reusable block with &name and reference it with *name, producing a compact source file that expands at parse time into a duplicated tree (or a cyclic one, which JSON cannot represent). The converter expands aliases into full copies by default. Cyclic references trigger an explicit error since JSON is strictly tree-shaped — you cannot serialize a graph without a custom reference scheme.

Third, merge keys. The special << key merges the content of one mapping into another, widely used in docker-compose for sharing service definitions. The converter resolves merges following the standard semantics (later keys override earlier ones in merge chains) before emitting JSON.

Fourth, block scalars. The folded (>) indicator joins lines with single spaces, the literal (|) indicator preserves newlines, and chomping indicators (- and +) control trailing newline handling. These map to plain JSON strings, with the exact whitespace behavior you specified in YAML.

Fifth, non-string keys. YAML allows mappings with complex keys (arrays, nested maps, booleans). JSON object keys must be strings, so the converter stringifies complex keys by default. If your YAML really needs non-string keys, output is not the real issue — your data model is fighting JSON and should probably be restructured.

Compared to js-yaml, PyYAML, or snakeyaml in a programming environment, this browser tool covers the same YAML 1.2 semantics without any install step. For scripting and automation, use those libraries directly — they integrate with your build system and add features like schema validation.

For ad-hoc conversion, debugging a complex Helm values file, or inspecting what a merge-heavy docker-compose file really produces, the browser tool is faster than running a short script. You paste, you see the expanded JSON, and you confirm your assumption about how the YAML will be interpreted.

kubectl convert and yq both do YAML to JSON transforms in a terminal workflow, which is great for CI pipelines and scripts. Neither gives you the instant visual diff of input vs output the way a browser tool does, so each has its place: CLI for automation, browser tool for exploratory work and one-off conversions.