JSON array count

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

Count structural occurrences in a JSON array in first-seen order.

Use when you need to: json array count · count json values · json value histogram.

Supported

• json array count
• count json values
• json value histogram

Not supported

• sort by count
• reference identity

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.
• Equality as json-deep-equal. First-seen order.
• Each output item is { value: clone, count } with null-prototype objects.

Input

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

Output

• items (array of object, required)
• items_in (integer, required)
• unique (integer, required)

Limits

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

Example

Request input:

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

Response:

{
  "result": {
    "items": [
      {
        "value": 1,
        "count": 2
      },
      {
        "value": "1",
        "count": 1
      }
    ],
    "items_in": 3,
    "unique": 2
  }
}

How to call it

MCP

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

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

HTTP (no key)

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

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

CLI

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

Get the client at /clients/cli/.

Related tools

• JSON array filter equals: Filter JSON array objects where a key equals a specific value.
• JSON array group count: Group an array of JSON objects by exact keys and return the count.
• 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.