Tutorials, deep-dives, and privacy-first thinking about developer tools.
Showing 1–12 of 28 posts
Learn how to test a regex pattern online without writing code: paste, highlight, and debug matches, plus why the same regex passes in Python but fails in JS.
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.
Convert PNG to WebP to cut image size by roughly 30% with no visible quality loss. A 2026 guide to lossless vs lossy, the Canvas API, and browser support.
Learn how to compare logs across UTC, PST, and JST in one view: normalize to Unix time, then convert cleanly with IANA zone names and ISO 8601.
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.
Convert PNG to JPG without that surprise black background. Here's why transparent pixels turn black and how to flatten onto the color you actually want.
Sign a JWT in the browser with HS256 and the Web Crypto API — five lines of JavaScript, no library, no server. The 2026 walkthrough.
When an API returns 401 Unauthorized in 2026, the JWT is usually the smoking gun. Decode the token, read exp, aud, iss — and fix the bug in 90 seconds.
Converting a Unix timestamp to a date is one division operation, but the timezone you format it in is the whole bug. Here's how to get it right.
A 400 Bad Request usually traces to a URL decoding bug. Here's how to decode the query string, spot the broken character, and ship a fix in five minutes.
Decode a JWT in 2026 with real Auth0 and Firebase tokens — header, payload, signature explained, common debugging traps, and why pasting tokens online is risky.
Decode Base64 strings into a real downloadable file — PDF, image, ZIP, audio — directly in your browser. No upload, no server, no plaintext leaks.