Tutorials, deep-dives, and privacy-first thinking about developer tools.
Showing 13–24 of 26 posts
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.
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.
Generate the 1024×1024 App Store icon plus every iPhone, iPad, Spotlight, and Settings size from one PNG. Free, no upload, transparency stripped — ready for App Store Connect in 30 seconds.
An online Markdown viewer that renders MD to HTML in real time — paste, see the formatted preview, copy the HTML or the rendered text. 100% in your browser.
A text-to-QR generator handles more than URLs: encode Wi-Fi, vCard, SMS, mailto, calendar, geo, and payment payloads with proper escaping for 2026.
Apple touch icon generator that builds every iOS, iPadOS, and Safari pinned-tab size from one source — no upload, no sign-up, on-brand in 30 seconds.
Free online mipmap generator — turn one source PNG into every Android density (mdpi → xxxhdpi) plus adaptive icons, ready as a drop-in res/ folder. No Android Studio, no upload.
Generate a UUID v4 in one line across browser, Node, Python, and CLI — and learn the three cases where UUID v4 is the wrong identifier to reach for.
Base64 explained with 10 working examples — encode and decode in the browser, terminal, JavaScript, Python, and JWTs. Includes URL-safe variant and the `==` padding rule.
Remove image backgrounds for free in your browser — no Photoshop install, no uploads, no signup. Works on photos, product shots, logos, and portraits.