YAML to JSON Converter

Paste a docker-compose file, Kubernetes manifest, CI config or OpenAPI spec and get formatted JSON with a collapsible tree. Anchors are expanded, documents separated by --- become an array, and nothing leaves your browser.

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Paste YAML
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Output
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How to convert YAML to JSON

  1. Paste YAML into the left panel, drag a .yaml or .yml file onto it, click upload (up to 5 MB) or use Load from URL.
  2. JSON appears on the right as you type. Use Tree to browse nested sections or Code for the text; the indent dropdown sets 2, 3 or 4 spaces or tabs.
  3. If the YAML is invalid, the error bar shows the line, the column and a pointer to the offending character. Typical causes are tabs used for indentation, an unclosed [ or {, and tags the JSON schema does not know.
  4. Click Copy or Download .json.

What the output looks like

Input:

app: inventory
replicas: 3
features:
  - search
  - export
database:
  host: db.internal
  port: 5432
  ssl: true
owner: null

Output:

{
  "app": "inventory",
  "replicas": 3,
  "features": ["search", "export"],
  "database": {
    "host": "db.internal",
    "port": 5432,
    "ssl": true
  },
  "owner": null
}

A multi-document file converts to an array:

name: api
---
name: worker

[{ "name": "api" }, { "name": "worker" }]

Limits and notes

  • Files up to 5 MB. Everything runs in your browser; nothing is sent to a server.
  • Typing follows the JSON schema of YAML: lowercase null, true, false and plain decimal numbers (including 1e3) are typed. ~, Null, True, yes, on, NO, 0x1f, 1_000, 010, .inf, dates and timestamps all stay strings. An empty value becomes ""; see null vs undefined in JSON for how to treat it downstream.
  • Tags are not supported. Custom tags such as !custom and even built-in ones such as !!timestamp raise an error. Remove the tag or quote the value.
  • Aliases are copied in full. JSON has no references, so a value used three times appears three times. Merge keys (<<) are not expanded.
  • Key order is preserved. Comments are dropped because JSON has none.
  • Dates stay as the text you wrote. JSON date format explains why ISO 8601 strings are the safe choice.
  • Need the reverse? Use JSON to YAML. To compare the formats for configuration files, read JSON vs YAML.

Frequently Asked Questions

What happens to a file with several --- documents?
Each document becomes one element of a JSON array, in order. A file with a single document converts to that object or array directly, with no wrapper.
Why is yes a string and not true?
The converter uses the JSON schema of YAML, where only lowercase null, true and false and plain decimal numbers are typed. yes, on, NO, True and ~ stay strings. This avoids the Norway problem, where NO silently becomes false. If you need a boolean, write true or false.
Are anchors and aliases supported?
Yes. &anchor defines a value and *alias repeats it; the JSON output contains a full copy at every alias. Merge keys (<<) are not expanded and appear as a literal "<<" key.
Why do dates come out as strings?
JSON has no date type, and the JSON schema of YAML does not parse timestamps, so 2026-01-08 is kept exactly as written. Your code can parse it when needed; see the JSON date format guide linked below.
What does an empty value become?
A key with nothing after the colon becomes an empty string. Write null explicitly if you want JSON null. The ~ shorthand is treated as the string ~ under the JSON schema.
Is my data uploaded?
No. Parsing and conversion run as JavaScript in your browser tab. You can disconnect from the network after the page loads and the tool keeps working.

Guides that go with this tool

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