Online developer tools for JSON, JWT and API debugging
Format and validate JSON, decode JWTs, encode Base64, test regex, convert Unix timestamps, format SQL and inspect API data without installing anything.
Start with the problem
Move from raw data to the next debugging decision
Choose the workflow that matches what you are investigating. Each path connects focused tools instead of dropping you into a wall of utilities.
API Payload Debugging
Format responses, validate JSON, inspect schemas and compare payload changes.
Open workflowJWT Inspection
Read claims, check expiry and spot risky token configuration without confusing decode with verification.
Open workflowLog Analysis
Clean noisy logs, extract trace IDs and connect failures across service boundaries.
Open workflowTimestamp Investigation
Compare Unix seconds, milliseconds, UTC and local dates while debugging events and token expiry.
Open workflowData Conversion
Move between JSON, YAML, Java DTOs and request formats without writing a scratch script.
Open workflowEncoding & Decoding
Inspect Base64, URL encoding and escaped values copied from requests, logs and integrations.
Open workflowCore tool processing stays in your browser
Core formatting, decoding, conversion and inspection actions run in your browser. Tool input is not uploaded to a Developer Debug Tools processing API.
No processing upload
Core tool input is handled client-side.
Focused workflows
Move between related developer tools quickly.
No account
Start debugging without signing in.
Analytics, advertising and hosting services may still receive standard request or device information as described in the privacy and cookie policies. Always redact active secrets and regulated data.
Work through a reproducible debugging example
All guides →Debug API JSON Responses: HTML Errors, Empty Bodies and Wrong Types
Debug JSON parsing failures with repeatable examples for HTML error responses, 204 empty bodies, string-versus-object payloads and valid JSON that violates an API contract.
4 min read · Includes a test fixtureHow to Analyze HAR Files for API Debugging
A practical workflow for reading HAR files, finding slow requests, spotting 4xx/5xx failures, and sharing safe network summaries.
3 min read · Includes a test fixtureHow to Read Java Stacktraces and Find Root Causes
Learn how to identify Caused by chains, application frames, framework noise, and the line of code most likely responsible for a Java failure.
3 min read · Includes a test fixtureHow to Detect Breaking Changes in OpenAPI / Swagger Files
A practical review process for comparing OpenAPI specs and identifying endpoint, method, response, and schema changes that can break clients.
2 min read · Includes a test fixturePopular developer workflows
Use the tools developers search for every day
Start with a concrete task, review the result and continue to the next relevant inspection step.