# JSON pick pointers

`json-pick-pointers` · version 1.0.0 · JSON & JSONL · free, no key needed

Pick cloned JSON values at explicit RFC 6901 pointers into a null-prototype map.

**Use when you need to: json pick pointers · project json pointers · select json pointers.**

## Supported

- json pick pointers
- project json pointers
- select json pointers

## Not supported

- reconstruct nested tree
- create missing
- json patch

## 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.
- pointers is a non-empty unique list. Duplicate pointers are invalid_input.
- Each pointer is resolved as json-pointer-get. Missing paths are invalid_input.
- Result values is a null-prototype object whose own keys are the pointer strings and whose values are deep clones.
- Pointer strings used as keys, including empty string for root, are ordinary own keys.

## Input

- `json` (any JSON value, required)
- `pointers` (array of string, required): min items 1; max items 256; each max length 1024

## Output

- `values` (object, required)

## Limits

- max json depth: 32
- max json nodes: 10000
- max pointers: 256
- max pointer chars: 1024

## Example

Request input:

```json
{
  "json": {
    "a": 1,
    "b": {
      "c": 2
    }
  },
  "pointers": [
    "/a",
    "/b/c"
  ]
}
```

Response:

```json
{
  "result": {
    "values": {
      "/a": 1,
      "/b/c": 2
    }
  }
}
```

## How to call it

### MCP

Connect `https://computefirst.net/mcp` ([setup](/docs#connect)), then call `execute` with:

```json
{
  "id": "json-pick-pointers",
  "version": "1.0.0",
  "input": {
    "json": {
      "a": 1,
      "b": {
        "c": 2
      }
    },
    "pointers": [
      "/a",
      "/b/c"
    ]
  }
}
```

### HTTP (no key)

```sh
curl -X POST https://computefirst.net/v1/tools/json-pick-pointers/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"json":{"a":1,"b":{"c":2}},"pointers":["/a","/b/c"]}'
```

The machine-readable contract is at [/v1/tools/json-pick-pointers/versions/1.0.0](/v1/tools/json-pick-pointers/versions/1.0.0).

### CLI

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

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

## Related tools

- [JSON array project](/tools/json-array-project): Select specific keys from each object in a JSON array.
- [JSON array filter equals](/tools/json-array-filter-equals): Filter JSON array objects where a key equals a specific value.
- [JSON flatten](/tools/json-flatten): Flatten a JSON value into a null-prototype map keyed by RFC 6901 JSON Pointers.
- [JSON omit pointers](/tools/json-omit-pointers): Deep-clone JSON and delete values at explicit RFC 6901 pointers.
- [JSON pointer list](/tools/json-pointer-list): List RFC 6901 pointers to every reachable JSON node, root first.
- [JSON unflatten](/tools/json-unflatten): Reconstruct a JSON value from a map of RFC 6901 JSON Pointers to leaves.