YAML to JSON Converter

How to use it

1. Type, paste or drop a file up to 20 MB — the badge names the detected direction, and clicking it (or pressing s) flips the conversion.
2. Set per-direction options: indentation, multi-document policy, date and non-finite handling one way; quoting, collection layout and line folding the other.
3. Read the fidelity banner under the output — it counts every expanded anchor, dropped comment, resolved tag and coerced key from this run.
4. Copy the result, download it as .json or .yaml, or let Share pack the tool state into the link.

Paste YAML to get JSON, or JSON to get YAML — the tool detects which one arrived, and the badge takes one click to override. Anchors expand with a count, a multi-document stream becomes a JSON array, integers past 2^53 keep every digit, and whatever JSON cannot carry — comments, tags, native timestamps — is counted in a banner instead of vanishing quietly. Documents up to 20 MB convert on this device.

How it works

YAML composes into a document model; nothing is edited as text. Merge keys and aliases resolve against their anchors under a 400-alias budget — expansion bombs refuse instead of hanging — tags settle into plain values, and one walk counts everything about to change. The JSON writer then prints from the resolved tree, keeping integer digits intact past 2^53.

The counts exist because the formats disagree on what a document holds. An expanded anchor becomes a copy at each alias position — same data, sharing gone. A dropped comment is deleted outright; JSON has no spelling for one. Each fact is a banner line with its count, so lossy never means quiet.

Examples

# defaults
x-img: &img nginx:1.25
web:
  image: *img
  replicas: 3

{
  "x-img": "nginx:1.25",
  "web": {
    "image": "nginx:1.25",
    "replicas": 3
  }
}

{"replicas": 3, "image": "nginx:1.25"}

replicas: 3
image: nginx:1.25

kind: Service
---
kind: Deployment
---
kind: ConfigMap

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

Every example on this page is executed against the same engine that powers the tool, on every build.

Common errors

Tabs are not allowed as indentation at line 2, column 1 — probable cause: YAML forbids tabs as indentation; replace the tab with spaces.

YAML reserves tabs, so a tab-indenting editor trips this on its first nested line. The caret frame marks the spot — reindent with spaces and the rest usually parses unchanged.

A mapping key at line 1, column 3 is a sequence — JSON object keys must be strings; enable "Stringify complex keys" to convert it to flow-scalar text.

The explicit ? syntax permits collections as keys; JSON has no such shape. With the named toggle on, the key [ a, b ] becomes the string "[ a, b ]" and a note counts the rewrite.

`.nan` at line 1, column 8 is not a finite number — JSON has no NaN or Infinity; set non-finite handling to "null" to emit null instead.

YAML spells .nan, .inf and -.inf; JSON spells none of them, so strict mode stops. The lenient setting writes null in their place and warns with the count.

Unexpected "'" at line 1, column 2 — probable cause: single-quoted strings are JSON5, not JSON; use double quotes.

JSON-side failures come from the same validator engine the site's JSON tools run, position and hypothesis included. Swap the quotes for double quotes and the conversion proceeds.

Keyboard shortcuts

⌘/Ctrl + Enter

Convert now — above 2 MB the tool waits for this key.

⌘/Ctrl + S

Download as .json or .yaml, following the direction.

⌘/Ctrl + C

Copy the whole output when nothing is selected.

⌘/Ctrl + Shift + C

Copy the whole output despite a selection.

s

Swap direction; one undo restores.

t

Next color theme.

? or ⌘/Ctrl + /

Open the shortcut overlay.

Esc

Dismiss the topmost overlay; panes stay put.