API Debugging Toolkit
Everything you need to inspect, decode, and fix API requests and responses — in one private workspace.
Debugging an API means jumping between the same handful of utilities: format the response, decode the token, check what that timestamp means, decode a Base64 chunk, test a regex, confirm what a 422 actually signals. This workspace puts all of them in one place, in the order you actually reach for them — so you stay in flow instead of hunting across tabs.
Everything runs in your browser. Auth responses, tokens, and customer payloads never leave your device, which matters when the thing you're debugging is production data.
The workflow
- 1
Make the response readable
Paste the raw API response and format it so the structure — and any syntax error — is obvious at a glance.
- 2
Spot what changed
Compare two responses (before/after a deploy, or expected vs actual) to isolate exactly which fields differ.
- 3
Inspect the auth token
Decode the JWT to check its claims, scopes, and expiry — the usual suspect behind a 401.
- 4
Translate the timestamps
Convert Unix timestamps to human dates to confirm token expiry, cache windows, and event ordering.
- 5
Decode encoded values
Decode Base64 fragments and URL-encoded query values that show up in tokens, headers, and links.
- 6
Confirm the status code
Look up exactly what the HTTP status means so you fix the right layer instead of guessing.
Tools in this workspace (10)
JSON Formatter & Validator
Format, validate, and minify JSON documents.
JSON Diff
Compare two JSON documents and highlight what changed.
JWT Decoder
Decode a JSON Web Token's header and payload.
Timestamp Converter
Convert between Unix timestamps and human-readable dates.
Base64 Encode/Decode
Encode text to Base64 or decode Base64 back to text.
URL Encode/Decode
Encode or decode strings for safe use in URLs.
Query String ⇄ JSON
Convert URL query strings to JSON and back.
Regex Tester
Test regular expressions against sample text with live matches.
HTTP Status Code Reference
Searchable reference of all standard HTTP status codes.
REST API Tester
Send GET/POST requests and inspect the JSON response and headers.
Frequently asked questions
What tools do I need to debug an API?＋
Most API debugging comes down to a JSON formatter/validator, a JWT decoder, a timestamp converter, Base64 and URL decoders, a regex tester, and an HTTP status reference. This toolkit bundles all of them.
Is it safe to paste production API responses here?＋
Nine of the ten tools here — the formatter, the JWT decoder, the converters, the regex tester — run entirely in your browser, so what you paste into them never leaves your machine. The exception is the REST API Tester, which has to send the request through our server to make it at all. Paste responses freely; think twice before putting a live production token into the tester.
Why is my API returning a 401 or 403?＋
A 401 usually means the auth token is missing, malformed, or expired (decode it to check the exp claim); a 403 means the token is valid but lacks the required scope or permission.
Is this API debugging toolkit free?＋
Yes — every tool is free, with no signup.
Related workflows
Last updated August 2026