JSON flatten

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

Flatten a JSON value into a null-prototype map keyed by RFC 6901 JSON Pointers.

Use when you need to: json flatten · flatten json to json pointers · expand nested json into pointer keys.

Supported

json flatten
flatten json to json pointers
expand nested json into pointer keys

Not supported

json pointer get
json pointer set
unflatten json pointers
read files
detect cycles

Behavior

value is any JSON object, array, string, boolean, null, or safe integer.
Non-finite numbers, non-integers, and integers outside Number.MAX_SAFE_INTEGER are rejected.
Output keys are RFC 6901 JSON Pointers; ~ is escaped as ~0 and / as ~1.
A root scalar or empty object or array maps to the empty pointer.
Nested empty objects and arrays are emitted as leaves at that pointer.
Result keys are inserted in lexicographic UTF-16 order of the pointers.
The pointers object is a null-prototype map of at most 5000 leaves; nesting depth is at most 16 from the root.

Input

value (any JSON value, required): JSON object, array, string, boolean, null, or safe integer

Output

pointers (object, required)

Limits

max depth: 16
max pointers: 5000
max output bytes: 1048576

Example

Request input:

{
  "value": {
    "a/b": 1,
    "empty": {},
    "list": [],
    "tags": [
      "a",
      "b"
    ],
    "tilde~key": false,
    "user": {
      "name": "רוני",
      "note": "line one\nline,two"
    }
  }
}

Response:

{
  "result": {
    "pointers": {
      "/a~1b": 1,
      "/empty": {},
      "/list": [],
      "/tags/0": "a",
      "/tags/1": "b",
      "/tilde~0key": false,
      "/user/name": "רוני",
      "/user/note": "line one\nline,two"
    }
  }
}

How to call it

MCP

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

{
  "id": "json-flatten",
  "version": "1.0.0",
  "input": {
    "value": {
      "a/b": 1,
      "empty": {},
      "list": [],
      "tags": [
        "a",
        "b"
      ],
      "tilde~key": false,
      "user": {
        "name": "רוני",
        "note": "line one\nline,two"
      }
    }
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/json-flatten/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"value":{"a/b":1,"empty":{},"list":[],"tags":["a","b"],"tilde~key":false,"user":{"name":"רוני","note":"line one\nline,two"}}}'

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

CLI

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

Get the client at /clients/cli/.

JSON unflatten: Reconstruct a JSON value from a map of RFC 6901 JSON Pointers to leaves.
JSON pointer list: List RFC 6901 pointers to every reachable JSON node, root first.
JSONL to array: Parse strict JSON Lines text into an array of JSON-safe values.
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 drop keys: Remove specific keys from each object in a JSON array.