JSON array unique

json-array-unique · version 1.0.0 · JSON & JSONL · free, no key needed

Deduplicate a JSON array by structural equality, keeping first-seen order.

Use when you need to: json array unique · unique json values · dedupe json array.

Supported

• json array unique
• unique json values
• dedupe json array

Not supported

• sort
• reference unique
• hash unstable

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; use own enumerable string keys only.
• Treat __proto__, constructor, and toString as ordinary own keys. Never mutate Object.prototype.
• Output objects must be Object.create(null). Deep-clone all returned JSON values.
• Bound walk: max depth 32, max nodes 10000, max UTF-8 JSON bytes 250KiB of the input document string if provided as text; when json is already a value, bound the walked node count and depth.
• items must be a JSON array.
• Two values are equal by the same rules as json-deep-equal.
• Keep the first occurrence. Output items are deep clones, objects null-prototype.

Input

• items (array of any, required): max items 10000

Output

• items (array of any, required)
• items_in (integer, required)
• items_out (integer, required)

Limits

• max json depth: 32
• max json nodes: 10000
• max items: 10000

Example

Request input:

{
  "items": [
    {
      "a": 1
    },
    {
      "a": 1
    },
    {
      "a": 2
    }
  ]
}

Response:

{
  "result": {
    "items": [
      {
        "a": 1
      },
      {
        "a": 2
      }
    ],
    "items_in": 3,
    "items_out": 2
  }
}

How to call it

MCP

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

{
  "id": "json-array-unique",
  "version": "1.0.0",
  "input": {
    "items": [
      {
        "a": 1
      },
      {
        "a": 1
      },
      {
        "a": 2
      }
    ]
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/json-array-unique/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"items":[{"a":1},{"a":1},{"a":2}]}'

The machine-readable contract is at /v1/tools/json-array-unique/versions/1.0.0.

CLI

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

Get the client at /clients/cli/.

Related tools

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