acento.io
Developer tool

JSON ↔ YAML Converter

Bidirectional conversion between JSON and YAML — runs entirely in your browser, so your data never leaves your machine.

By Carlos Suárez , Systems engineer
Last updated:

What this JSON ↔ YAML converter does

This English-language converter handles both directions: paste JSON and get clean YAML, or paste YAML and get valid JSON — no server round-trip required. It uses js-yaml under the hood, which correctly preserves types: numbers stay numbers, booleans stay booleans, and nested arrays and maps are handled faithfully. The IETF formalized the JSON specification in RFC 4627 back in 2006, later updated to RFC 8259 in 2017 — so JSON's structure is well-defined and unambiguous. The converter respects that spec. One important caveat: YAML comments are dropped on conversion to JSON, because JSON has no comment syntax. YAML anchors and aliases are also expanded rather than preserved. The tool warns you when it detects comment-heavy YAML, so you're never surprised. 100% client-side — your data never leaves your browser. No uploads, no tracking, no server logs.

Features

  • Bidirectional conversion. Switch between JSON → YAML and YAML → JSON with a single click. The side-by-side layout makes it easy to compare input and output at a glance.
  • Type-accurate output. Numbers, booleans, nulls, arrays, and nested objects are all preserved correctly — no silent coercion to strings.
  • Honest about data loss. YAML comments cannot survive a round-trip through JSON. The tool detects comment-laden YAML and warns you before you lose anything important.
  • Instant parse errors. Invalid JSON or YAML surfaces a clear parser error immediately, so you can fix the issue without guessing where things went wrong.
  • One-click copy. Copy the converted output to your clipboard in one click. Useful when piping results into a config file or API call.
  • No install, no account. Runs entirely in-browser using js-yaml. Nothing is sent to a server — ideal for config files that may contain credentials or internal hostnames.

How to use the JSON ↔ YAML converter

Paste your input, pick a direction, and the output is ready immediately. No form submission, no waiting.

  1. Paste your input. Drop your JSON or YAML text into the left panel. For example, a Kubernetes Deployment manifest or a package.json snippet.
  2. Choose a direction. Click "JSON → YAML" or "YAML → JSON" at the top. Use "↻ Swap" to flip the panels if you want to work in the other direction.
  3. Review the output. The right panel updates instantly. If your YAML contained anchors like &defaults or *defaults, check that the expanded output matches your intent.
  4. Copy and paste. Click "Copy" to grab the result. You can then paste it directly into your CI config, a kubectl apply -f - pipeline, or an API body.

Common use cases

  • Kubernetes manifest inspection. Kubernetes accepts both YAML and JSON. Convert a YAML manifest to JSON when you need to feed it into a JSON-native API or validate it with a JSON Schema linter.
  • CI pipeline config debugging. GitHub Actions and GitLab CI configs are written in YAML. Converting them to JSON lets you query fields with jq or inspect structure with JSON tools — useful when a pipeline behaves unexpectedly. You can also check our [JSON formatter](/en/json-formatter/) to pretty-print the result.
  • Cross-system data migration. When one system exports JSON and another expects YAML (or vice versa), this converter handles the translation in seconds — including deeply nested configs from teams in San Francisco to Chicago.
  • TypeScript type generation. Convert a YAML config to JSON first, then use the [JSON to TypeScript](/en/json-to-typescript/) tool to generate typed interfaces — a common pattern when onboarding a YAML-based config into a typed codebase.
  • Quick syntax validation. If you're unsure whether your YAML is valid, pasting it here is a fast sanity check. A malformed document shows a parser error with line context right away.

Frequently asked questions

Is my data sent to a server when I convert?

No. The converter runs entirely in your browser using js-yaml compiled to JavaScript. Nothing is transmitted, logged, or stored anywhere. You can use it safely with internal configs, API keys, or any sensitive data.

Why do my YAML comments disappear after converting to JSON?

JSON has no comment syntax — the RFC 8259 spec explicitly excludes them. When js-yaml parses your YAML, comments are discarded before the JSON serializer ever sees them. This is expected behavior, not a bug. If preserving comments matters, keep the original YAML file and treat the JSON output as a derived artifact.

What happens to YAML anchors and aliases?

Anchors (&name) and aliases (*name) are YAML-specific features with no JSON equivalent. The converter expands them fully — every alias becomes an inline copy of the anchored value. The resulting JSON is semantically equivalent but larger. If your YAML uses anchors for DRY config, be aware the output won't stay DRY.

Does 'false', 'no', or 'off' convert to a boolean?

It depends on the YAML version. In YAML 1.1 (used by many older tools), no and off are treated as boolean false. In YAML 1.2, they are plain strings. This converter uses js-yaml's default behavior, which follows YAML 1.2 for those edge cases. If you see unexpected string values, check whether your original toolchain assumed YAML 1.1.

Can I convert a large file?

Yes, within browser memory limits. For most config files — even large Helm charts or OpenAPI specs — performance is instant. Very large files (several MB of deeply nested YAML) may take a moment, but there is no file-size cap imposed by the tool itself.

Why does my YAML use spaces and not tabs?

The YAML specification forbids tab characters for indentation — only spaces are allowed. This is a common stumbling block when editing YAML in editors that default to tabs. If you paste YAML with tab indentation, the parser will throw an error. The fix is to replace tabs with spaces (usually two or four per level) before converting.