Tutorials, deep-dives, and privacy-first thinking about developer tools.
Showing 61–72 of 105 posts
Side-by-side and unified diff show the same edits two ways. Learn how each format reads, what the @@ hunk header means, and when to pick which.
Understand regex capture groups, backreferences, and the $1, $&, and $<name> replacement tokens — with copy-paste JavaScript examples that actually work.
A browser image converter often beats Photoshop's Save As for plain format changes, batch jobs, and privacy. Here is exactly when each one wins in 2026.
Regex lookahead vs lookbehind, explained with five production patterns: password rules, thousands separators, price parsing, and camelCase splits.
A pattern that works in PCRE can silently break in JavaScript or Python re. Here are the regex flavor differences that explain why, with fixes for each.
How to match a URL with regex and survive the three edge cases that break most patterns: trailing punctuation, balanced parentheses, and scheme-less links.
Batch convert 50 images to WebP, AVIF, JPG, or PNG at once, entirely in your browser — no upload, no sign-up, and your files never leave your device.
Unix timestamp 1700000000 was Tuesday, November 14, 2023, 22:13:20 UTC. Learn how to date any timestamp from its leading digits, no converter needed.
Convert any date to a Unix timestamp in Bash, Python, JavaScript, and SQL with copy-paste one-liners — plus the timezone trap each language hides.
Learn how to convert JPG to PNG in your browser, why it never restores lost quality, and the three cases where converting actually helps instead of bloating files.
JWT exp, nbf, and iat are Unix timestamps in seconds. Learn to read them in 3 seconds, convert them to a date, and check token expiry by hand.
Learn what the JWT exp, nbf, and iat claims mean, how to read token expiry without doing epoch math by hand, and the clock-skew gotchas that bite in 2026.