JSON merge patch

json-merge-patch · version 1.0.0 · JSON & JSONL · free, no key needed

Apply an RFC 7396 JSON Merge Patch to a JSON value.

Use when you need to: json merge patch · apply json merge patch · rfc 7396 merge patch.

Supported

json merge patch
apply json merge patch
rfc 7396 merge patch

Not supported

json patch rfc 6902
elementwise array merge
json pointer set
fuzzy merge
read files
fetch urls

Behavior

If patch is not a JSON object, including when it is an array or null, the result is the patch.
If patch is an object and target is not a non-array object, merging starts from an empty object.
A null patch value deletes that own key; deleting a missing key is a no-op.
Nested objects are merged recursively in Object.keys order; arrays and other non-objects replace.
Result objects are null-prototype copies. Inputs are not mutated.
Prototype-like names are ordinary own keys.
JSON numbers must be safe integers. Depth is at most 16 and at most 5000 own keys are visited per value.

Input

target (any, required)
patch (any, required)

Output

value (any, required)

Limits

max depth: 16
max own keys visited: 5000
max output bytes: 1048576

Example

Request input:

{
  "target": {
    "title": "Goodbye!",
    "author": {
      "givenName": "John",
      "familyName": "Doe"
    },
    "tags": [
      "example",
      "sample"
    ],
    "content": "This will be unchanged"
  },
  "patch": {
    "title": "Hello!",
    "phoneNumber": "+01-123-456-7890",
    "author": {
      "familyName": null
    },
    "tags": [
      "example"
    ]
  }
}

Response:

{
  "result": {
    "value": {
      "title": "Hello!",
      "author": {
        "givenName": "John"
      },
      "tags": [
        "example"
      ],
      "content": "This will be unchanged",
      "phoneNumber": "+01-123-456-7890"
    }
  }
}

How to call it

MCP

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

{
  "id": "json-merge-patch",
  "version": "1.0.0",
  "input": {
    "target": {
      "title": "Goodbye!",
      "author": {
        "givenName": "John",
        "familyName": "Doe"
      },
      "tags": [
        "example",
        "sample"
      ],
      "content": "This will be unchanged"
    },
    "patch": {
      "title": "Hello!",
      "phoneNumber": "+01-123-456-7890",
      "author": {
        "familyName": null
      },
      "tags": [
        "example"
      ]
    }
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/json-merge-patch/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"target":{"title":"Goodbye!","author":{"givenName":"John","familyName":"Doe"},"tags":["example","sample"],"content":"This will be unchanged"},"patch":{"title":"Hello!","phoneNumber":"+01-123-456-7890","author":{"familyName":null},"tags":["example"]}}'

The machine-readable contract is at /v1/tools/json-merge-patch/versions/1.0.0.

CLI

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

Get the client at /clients/cli/.

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.
JSON array count: Count structural occurrences in a JSON array in first-seen order.
JSON array distinct by: Deduplicate a JSON array of objects based on specific keys.
JSON array drop keys: Remove specific keys from each object in a JSON array.