Guides

How to Debug API JSON Responses — Developer Guide

API integration often fails due to malformed JSON responses. This workflow shows how to validate, format, and inspect API payloads quickly.

Open JSON Validator

Step-by-Step

  1. 1

    Copy the raw API response

    From browser DevTools Network tab (Copy as cURL), curl output, or server logs.

  2. 2

    Convert cURL to code (optional)

    Use the cURL Converter to turn DevTools cURL into fetch, Python, Java, or PHP code for reproduction scripts.

  3. 3

    Validate syntax

    Paste into the JSON Validator. Fix any syntax errors using line numbers.

  4. 4

    Format for readability

    Use the JSON Formatter to pretty-print, explore the tree view, or convert to YAML/TOML.

  5. 5

    Inspect tokens if present

    If the response contains JWT tokens, decode them with the JWT Decoder.

Common API JSON Issues

Trailing commas from JavaScript serialization, BOM characters from file exports, double-encoded JSON strings, and HTML error pages returned instead of JSON.

Related Tools

JSON FormatterJWT DecodercURL Converter

Frequently Asked Questions

Should I validate JSON client-side?

Validate during development and debugging. Production apps should validate API responses programmatically with schema validation (JSON Schema, Zod).