Blog
Guides and tips to help you get the most out of free online tools.
Percentage Math Without Tears: Discounts, Increases, and Reverse Percentages
The three types of percentage problems, how to reverse a percentage (the one everyone gets wrong), and the mental math shortcuts that make it instant.
Unix Timestamps Explained: Epoch Time, Time Zones, and the 2038 Problem
What Unix time actually counts, why seconds vs. milliseconds causes so many bugs, how time zones fit in, and what happens in January 2038.
Color Contrast and Accessibility: A Practical Guide to WCAG
What contrast ratio actually measures, the WCAG AA and AAA thresholds, the design patterns that fail most often, and how to fix them without ruining your palette.
Base64 Explained: What It Is, What It Isn't, and When to Use It
Why Base64 exists, how the encoding actually works, why it isn't encryption, and the real-world cases where you'd use it - or shouldn't.
Hashing Explained: MD5 vs SHA-256, and Why It Matters
What cryptographic hashing actually does, why MD5 is broken, when SHA-256 is the right choice, and why none of them should store your passwords.
UTM Parameters: The Complete Guide to Tracking Your Marketing
What UTM parameters are, what each of the five tags means, naming conventions that keep your analytics clean, and mistakes that ruin your data.
Regular Expressions for Beginners: A Practical Crash Course
Learn regex from zero with plain-English explanations and real patterns you can copy - emails, dates, phone numbers, and the gotchas that trip everyone up.
WebP vs AVIF vs JPEG vs PNG: Which Image Format Should You Use?
A practical comparison of the four main web image formats - file sizes, quality, browser support, and exactly which one to pick for each job.
JWTs Explained: How They Work and 6 Mistakes That Get Apps Hacked
What's actually inside a JSON Web Token, how signing works, and the six most common JWT security mistakes developers still make.
How Mortgage Payments Actually Work (Amortization Explained)
Where your mortgage payment really goes each month, why early payments are almost all interest, and how extra payments save tens of thousands.
How to Create Strong Passwords (and Actually Remember Them)
A practical guide to strong passwords: what makes them secure, common mistakes to avoid, and how to generate and remember them.
How to Compress Images for a Faster Website
Large images are the #1 cause of slow web pages. Learn how to compress and resize images the right way to speed up your site.
How to Split a PDF for Free (Without Uploading It)
Learn how to extract pages or split a PDF into separate files for free - safely, in your browser, without uploading sensitive documents.
How Compound Interest Works (With Simple Examples)
Understand compound interest, the formula behind it, and why starting early matters so much - with worked examples you can try yourself.