Json group by

An MCP tool from the Data Formats server, hosted on mcp.hjlabs.in.

Group an array of objects by a key (dotted paths allowed) and optionally aggregate a numeric field per group: count, sum, avg, min, max.

Name on the gateway: data__json_group_by · read-only.

Parameters

Name	Type	Description
`json` required	`string`	An array of objects.
`by` required	`string`	The key to group by, e.g. "country" or "address.city".
`aggregate`	`string`	A numeric field to summarise per group. Optional.

Through the Smart Gateway, any client can run it by name with call_tool, or let the gateway find it with search_tools:

call_tool arguments

{
  "name": "data__json_group_by",
  "arguments": {
    "json": "…",
    "by": "…"
  }
}

Or connect the Data Formats server directly, which lists 26 tools including this one:

Run in your terminal

claude mcp add --transport http hj-data https://mcp.hjlabs.in/mcp/data \
  --header "Authorization: Bearer YOUR_API_KEY"

Use the json group by tool with json set to ….