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Developer Guides
Practical guides and references for developers. Work through concrete examples, check common mistakes, and try the related tools without uploading your input.
How to Format and Validate JSON
A practical workflow for fixing JSON syntax, reviewing formatted data, and understanding what validation cannot prove.
SecurityHow to Decode and Debug JWT Tokens
Inspect JWT headers and claims locally, interpret expiry in seconds, and separate decoding from signature verification.
APIHow to Detect Breaking Changes in OpenAPI
Compare API contracts, investigate removed operations and required inputs, and understand the limits of a local OpenAPI diff.
SchedulingHow Cron Expressions Work
Read five-field cron schedules, check ranges and steps, and avoid timezone and scheduler-dialect mistakes.
Date & TimeUnix Timestamps Explained
Convert epoch values accurately, distinguish seconds from milliseconds, and interpret UTC versus local displays.
EncodingBase64 Encoding and Decoding Explained
Understand text-to-byte encoding, padding, Unicode round trips, and why Base64 does not protect secrets.
EncodingURL Encoding Explained
Encode individual URL components safely, distinguish plus signs from spaces, and avoid double encoding.