Response Formatter: Pretty-Print and Analyze Any API Response

API responses arrive as dense walls of text — a 200-field JSON object on a single line. A response formatter adds indentation, syntax highlighting, and collapsible sections that let you navigate complex payloads at the speed of thought.

What Is Response Formatter?

A response formatter takes raw API output (JSON, XML, HTML, or plain text) and renders it with consistent indentation, color-coded syntax, and interactive folding. It highlights data types, shows string lengths, and counts array elements — making large responses manageable.

How to Use Response Formatter on DevToolHub

1. Open the Response Formatter tool on DevToolHub — no signup required.
2. Paste the raw API response into the input panel.
3. Select the format (JSON, XML, HTML) or let auto-detection handle it.
4. View the formatted output with syntax highlighting and collapsible nodes.
5. Click any object or array to collapse/expand nested data.
6. Copy the formatted version or download it for documentation.

Formatting a Complex JSON Response

A typical unformatted API response:

{ "users": [{ "id": 1, "name": "Alice", "address": { "city": "Portland", "state": "OR", "zip": "97201" }, "roles": ["admin", "editor"], "lastLogin": "2024-01-15T08:30:00Z" }], "total": 1, "page": 1 }

After formatting, each field sits on its own line with proper nesting — address is clearly a nested object, roles is an array.

Spotting Null Values in Deep Structures

When debugging, null values cause crashes. Formatted responses reveal them:

{
  "order": {
    "id": "ord_99",
    "customer": {
      "id": "cust_42",
      "name": "Bob",
      "email": null,
      "phone": null
    },
    "items": [],
    "total": 0
  }
}

At a glance: email and phone are null, items is empty, total is zero — three potential issues spotted immediately.

Formatting XML SOAP Responses

Legacy APIs still return XML:

<soap:Envelope>
  <soap:Body>
    <GetUserResponse>
      <User>
        <Id>42</Id>
        <Name>Alice</Name>
        <Status>Active</Status>
      </User>
    </GetUserResponse>
  </soap:Body>
</soap:Envelope>

Proper indentation reveals the nesting hierarchy that's invisible in raw single-line XML.

Pro Tips

• Use JSON path — click a field to copy its JSON path (e.g., $.users[0].address.city) for direct access in code.
• Check array lengths — the formatter shows element counts next to arrays so you know if pagination is working.
• Compare responses — format two versions side by side to spot what changed between API versions.
• Detect type mismatches — the formatter color-codes strings, numbers, booleans, and nulls differently.

When You Need This

• Debugging unexpected API behavior by inspecting the raw response
• Documenting API responses for team knowledge bases
• Comparing responses between staging and production environments
• Validating that your API returns the correct data structure