JSON deep diff

json-deep-diff · version 1.0.0 · JSON & JSONL · free, no key needed

Bounded deterministic JSON difference records. Not a JSON Patch implementation.

Use when you need to: json deep diff · diff json values · json structural diff.

Supported

• json deep diff
• diff json values
• json structural diff

Not supported

• json patch apply
• json merge patch
• text diff

Behavior

• Accept only JSON values: null, boolean, finite number, string, array, and plain objects.
• Reject NaN, Infinity, -Infinity, undefined, BigInt, functions, symbols, Date, Map, Set, RegExp, boxed primitives, Buffer, and sparse holes.
• Canonicalize -0 to 0.
• Objects may have null or Object.prototype; comparison uses own enumerable string keys only.
• Treat __proto__, constructor, and toString as ordinary own keys. Never mutate Object.prototype.
• Output objects are Object.create(null). Returned JSON values are deep-cloned.
• Bound walk: max depth 32, max nodes 10000 per value.
• Object keys are compared using the sorted union of own keys (UTF-16 lexicographic). Arrays are index-aligned; extra tail elements are add/remove.
• Each change is { pointer, op, left?, right? } where op is replace | add | remove. This is not RFC 6902 JSON Patch.
• replace: both present and not equal (left from a, right from b). add: only in b. remove: only in a.
• Do not recurse into a subtree after emitting replace/add/remove for that node.
• More than 1000 changes is rejected.

Input

• a (any JSON value, required)
• b (any JSON value, required)

Output

• changes (array of object, required): max items 1000

Limits

• max json depth: 32
• max json nodes: 10000
• max changes: 1000

Example

Request input:

{
  "a": {
    "x": 1,
    "y": 2
  },
  "b": {
    "x": 1,
    "y": 3,
    "z": 4
  }
}

Response:

{
  "result": {
    "changes": [
      {
        "pointer": "/y",
        "op": "replace",
        "left": 2,
        "right": 3
      },
      {
        "pointer": "/z",
        "op": "add",
        "right": 4
      }
    ]
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "json-deep-diff",
  "version": "1.0.0",
  "input": {
    "a": {
      "x": 1,
      "y": 2
    },
    "b": {
      "x": 1,
      "y": 3,
      "z": 4
    }
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/json-deep-diff/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"a":{"x":1,"y":2},"b":{"x":1,"y":3,"z":4}}'

The machine-readable contract is at /v1/tools/json-deep-diff/versions/1.0.0.

CLI

node cli.mjs run json-deep-diff 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• JSON deep equal: JSON-only structural equality. Object key order does not matter; array order does.
• JSON array count: Count structural occurrences in a JSON array in first-seen order.
• JSON array unique: Deduplicate a JSON array by structural equality, keeping first-seen order.
• Array to JSONL: Serialize an array of JSON-safe values as JSON Lines text.
• JSON array anti join: Anti join two JSON arrays of objects on exact keys.
• JSON array concat: Concatenate multiple JSON arrays of objects into one.