# 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:

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

Response:

```json
{
  "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](/docs#connect)), then call `execute` with:

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

### HTTP (no key)

```sh
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](/v1/tools/json-array-count/versions/1.0.0).

### CLI

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

Get the client at [/clients/cli/](/clients/cli/).

## Related tools

- [JSON array filter equals](/tools/json-array-filter-equals): Filter JSON array objects where a key equals a specific value.
- [JSON array group count](/tools/json-array-group-count): Group an array of JSON objects by exact keys and return the count.
- [JSON array unique](/tools/json-array-unique): Deduplicate a JSON array by structural equality, keeping first-seen order.
- [Array to JSONL](/tools/array-to-jsonl): Serialize an array of JSON-safe values as JSON Lines text.
- [JSON array anti join](/tools/json-array-anti-join): Anti join two JSON arrays of objects on exact keys.
- [JSON array concat](/tools/json-array-concat): Concatenate multiple JSON arrays of objects into one.