Developer guides
Short, practical articles about the formats and problems behind the tools on this site, including JSON, CSV, JWT, Base64, cron, hashing and timestamps. Every guide includes code you can run.
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Unix Timestamp to Date in JavaScript, PHP, Python and MySQL
Convert Unix timestamps to dates in JavaScript, PHP, Python, MySQL and PostgreSQL: seconds vs ms, time zones, DST and the 2038 limit.
· dates, timestamps
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SHA-256 vs HMAC-SHA256: Differences and Code Examples
SHA-256 hashes a message; HMAC-SHA256 adds a secret key. When to use each, why neither suits passwords, and how to verify both.
· security, hashing
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Fix JSON.parse Unexpected Token Errors: Every Cause
Every JSON.parse SyntaxError and its fix: unexpected token <, single quotes, trailing commas, comments, end of input, BOM and NaN.
· json, javascript, debugging
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PHP Array to JSON: json_encode Flags Explained
How json_encode picks an object or array, what each flag changes, where floats and depth go wrong, and why it returns false silently.
· php, json
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Base64 vs URL Encoding: When to Use Which
Base64 and percent-encoding solve different problems. How each works byte by byte, which Base64 variant to pick, and when to use each.
· base64, url, encoding
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Cron Expression Cheat Sheet With 30 Examples
The five cron fields, every special character, and 30 ready-to-copy schedules in plain English, plus time zone pitfalls and how each cron platform differs.
· cron, devops, scheduling
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JWT Explained: Header, Payload, Signature and Decoding
How a JWT is built from header, payload and signature, how to decode one in JavaScript, PHP or Python, and mistakes that make JWTs unsafe.
· jwt, security, authentication
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Convert JSON to CSV in JavaScript, With or Without a Library
Convert JSON to CSV in plain JavaScript with correct RFC 4180 escaping. Flatten nested objects, write the file in Node.js, or trigger a browser download.
· json, csv, javascript