Data & Requests · LOCAL TOOL

JSON Field Coverage

Inspect an array of JSON objects to see how consistently each top-level field appears. Every missing value, null, and observed type is linked to one-based record positions.

Runs in this page
No API call

WORKSPACEINPUT → RESULT

Your input

LOCAL

Result

Run the tool to see a result.

Your result will appear here. Input is not saved.

Browser-side processingNothing is sent to a tool API.

WHY THIS TOOL EXISTS

A focused job, not a black box.

An explicit null remains different from a field that was omitted. This makes it easier to investigate a mixed export and choose representative records for a schema discussion.

How to use it

Paste a representative array of objects.
Compare each field's presence and type groups.
Use the listed record positions to inspect unexpected omissions or nulls.

TRY A WORKING EXAMPLE

Start with known input.

Load this sample into the workspace, run the tool, and compare the result shown below.

Show sample input

{
  "source": "[{\"id\":1,\"email\":null},{\"id\":2},{\"id\":\"3\",\"email\":\"[email protected]\"}]"
}

Expected sample result from the local tool

3 record(s) · 2 top-level field(s).

{
  "records": 3,
  "fields": [
    {
      "key": "email",
      "present": 2,
      "total": 3,
      "missingRows": [
        2
      ],
      "nullRows": [
        1
      ],
      "types": {
        "null": [
          1
        ],
        "string": [
          3
        ]
      }
    },
    {
      "key": "id",
      "present": 3,
      "total": 3,
      "missingRows": [],
      "nullRows": [],
      "types": {
        "number": [
          1,
          2
        ],
        "string": [
          3
        ]
      }
    }
  ]
}

LIMITS AND INTERPRETATION

What the result cannot tell you.

Top-level fields only; nested objects and arrays are reported as types. Sample coverage cannot prove required fields or production distributions. Maximum 10000 records.

Inputs are processed in this page and are not written to local storage.