Common API workflows
HTTP problems usually need two kinds of evidence: what was actually sent and received, and what the protocol says it means. A HAR capture or an API response shows the first; status code, header and MIME references explain the second. Network calculators describe address ranges and conventions, not which services are actually running.
Investigate an API request
Inspect a HAR capture for slow or failed requests, check response headers and look up status codes. Validate an OpenAPI document to compare the response with the documented contract.
- HAR Analyzer — Inspect request waterfalls, details and redacted HAR exports.
- HTTP Header Checker — Explain response headers and flag CORS, cache and cookie mistakes.
- HTTP Status Codes — Look up any HTTP status code, its causes and fixes.
- OpenAPI Validator — Validate API documents and browse their endpoints.
Reproduce a request in code
Paste a curl command copied from browser developer tools, send it from the API client and generate the equivalent Python, JavaScript or Go code. Remove cookies and tokens before sharing the result.
- cURL Converter — Turn curl commands into code in 8 languages.
- API Debugging Lab — Send HTTP requests and inspect WebSocket or SSE events.
- cURL to Python — Convert curl commands to Python requests code.
- cURL to JavaScript — Convert curl commands to fetch or axios code.
Keep captured traffic private
HAR files and HTTP headers can contain cookies, authorization tokens and personal data. The analyzer processes captures locally and can export a redacted copy. Hostnames and URL paths may still identify a system, so inspect the resulting file before sharing it.
Browsers limit what an API client can send
Requests from a web page follow CORS rules, and browsers control some headers such as Host and Cookie. When a request works with curl but fails here, check the CORS response headers before assuming the API is broken.
Frequently asked questions
Do these tools call my API or scan my website?
Only the API Debugging Lab sends requests, and only to the URLs you enter. The HAR analyzer, OpenAPI validator and curl converters inspect data you provide locally.
Where are DNS lookup, CIDR and port tools?
Open Network for DNS record lookups, subnet calculations, IP conversion and port references.
Tools process your input on this device. Read the privacy policy, or save the tool library for offline use.