API debugging tools for payloads, tokens, headers, URLs, and responses
API debugging is faster when each part of the request is readable on its own. This category connects payload formatting, token inspection, header parsing, query parsing, cURL conversion, and response status lookup into one practical workflow.
Tools in this workflow
Formatters
OpenJSON Formatter
Pretty-print raw JSON, minify payloads, and inspect syntax errors with clear feedback.
API & Auth
OpenJWT Decoder
Decode JWT headers and payloads, inspect claims, and check expiry fields at a glance.
API & Auth
OpenHeader Parser
Parse raw HTTP headers into readable key and value pairs for request and response debugging.
API & Auth
OpenQuery Param Parser
Parse URLs and raw query strings into decoded key and value pairs and rebuild them cleanly.
API & Auth
OpenAPI Test Case Builder
Create QA-ready API test checklists and Gherkin drafts from endpoint details, sample responses, or error bodies.
Converters
OpencURL to fetch
Convert common cURL commands into readable JavaScript fetch examples for frontend work.
Converters
OpencURL to Java
Turn common cURL commands into readable Java HttpClient examples with headers and body preserved.
API & Auth
OpenHTTP Status Code Explorer
Search HTTP status codes by number or meaning and see common developer use cases fast.
Converters
OpenTimestamp Converter
Convert Unix seconds, Unix milliseconds, and ISO date strings with readable UTC and local output.
Validators & Testers
OpenJSON Schema Generator
Generate a draft JSON Schema from a sample API payload for contracts, tests, and documentation.
Related guides
What is JSON Formatter and how to use it
Learn what a JSON formatter does, why valid JSON matters, and how developers use formatting during API debugging.
JWT Decode explained
Learn how JWT decoding works, what header and payload claims mean, and what decoding does not prove.
URL Encoding explained
Understand URL encoding, percent escapes, query strings, and how to debug encoded URLs safely.
FAQ
What should I check first when an API response fails?
Start with the status code, then inspect headers, payload shape, token claims, query parameters, and timestamps. Most API failures show up in one of those places.
Can I use these tools with sensitive API data?
The tools are browser-based, but you should still redact tokens, credentials, personal data, and production identifiers before sharing output.