In-depth guides for the tools developers reach for every day. QR codes, CSS and JS minification, Unix timestamps — explained with real use cases and zero filler. Every guide is paired with a free Devryo tool so you can follow along directly in your browser.
A practical guide to 1D barcode formats — how CODE128, EAN-13, EAN-8, and UPC-A differ, how the check digit algorithm works, print-quality tips (SVG vs PNG), GS1 registration requirements, and how to generate barcodes free in your browser.
How to count characters and words for social media, SEO, and writing. Includes character limits for Twitter/X, Instagram, LinkedIn, meta tags, and best practices for each platform.
What makes a strong password — length requirements, character types, passphrase vs random password, password managers, and how to check your password strength. Includes a free password generator tool.
Learn how to reduce image file size without ruining quality. Covers lossy vs lossless compression, when to use JPG, PNG, or WebP, how image size affects Core Web Vitals, and how to compress files right in your browser.
Date formatting confusion is surprisingly common. Learn the most widely used date formats — ISO 8601, RFC 2822, US-style MM/DD/YYYY — what each means, when to use them, and how to convert between them without bugs.
"Ships in 3 business days" — when does it actually arrive? Learn what business days mean, how to count them correctly, why holidays complicate things, and how to calculate them automatically.
Need to know how many days until a deadline, birthday, or event? Learn how to calculate remaining days manually, with spreadsheet formulas, and using browser tools — plus tips for deadline management.
Amida Kuji (ladder lottery) is a fair drawing method used across Japan. Learn how the vertical and horizontal lines determine outcomes, why it produces unbiased results, and how to create one digitally.
An online roulette wheel is a fast, fair way to make decisions. Learn how to set it up for task assignments, turn orders, lunch picks, and classroom activities — and why random selection removes friction.
Paper lotteries are slow and easy to rig. Learn how to run fair online drawings using ladder lottery, roulette wheels, and random number tools — with practical examples for teams, classrooms, and giveaways.
The QR code guide is a good starting point — QR codes come up more often than you'd expect, and the Devryo generator lets you try everything instantly.