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Sealpaste

YAML to JSON Converter

Convert YAML (Kubernetes, Compose, OpenAPI, CI) to JSON. Indentation mistakes are reported with the line and column.

Direction
Indent

Input YAML

JSON

How to use it

  1. 1Paste YAML on the left, or open a .yml/.yaml file.
  2. 2Fix any error shown under the input.
  3. 3Copy or download the JSON.

Private by design

Everything runs in this browser tab. Your input is never uploaded, logged or saved on a server, and there are no public "recent" pages. Close the tab and it's gone.

How we keep it private

Examples

Compose service to JSON

Input

api:
  image: node:22
  ports:
    - "3000:3000"

Output

{
  "api": {
    "image": "node:22",
    "ports": [
      "3000:3000"
    ]
  }
}
Several documents

A file with several --- documents becomes a JSON array.

Input

kind: Service
---
kind: Deployment

Output

[
  {
    "kind": "Service"
  },
  {
    "kind": "Deployment"
  }
]

YAML details that change values

A few YAML rules surprise people when the result is JSON:

  • Anchors and aliases (&base, *base, <<: *base) are expanded into full copies.
  • This converter follows YAML 1.2: yes/no/on/off stay strings; only true and false are booleans.
  • Unquoted values like 1.10 become numbers (1.1). Quote version strings: "1.10".
  • Very large integers keep every digit in the JSON output.

Frequently asked questions

Why does my YAML fail to parse?

Most often it is indentation: mixing tabs and spaces, or a list item not lined up under its parent. The error shows the line and column where the parser gave up.

Can it convert a file with several documents?

Yes. Documents separated by --- become items of a JSON array, in order.

Is my config uploaded anywhere?

No. Conversion runs in your browser. Kubernetes manifests, CI files and .env-style configs often hold secrets; they never leave your machine here, and the page warns you if it spots any.