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Tutorials, deep dives, and how-tos.

Practical guides on image formats, PDF tricks, security, and developer tools. No fluff, no signup, no paywall.

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CalculatorsFeatured

Mortgage payments explained: how the monthly math actually works

The amortization formula in plain English. Why your first payment is almost all interest, how a 30-year vs 15-year mortgage really compares, and what changes when rates move 1%.

Jun 8, 202612 min read
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Guides

Feet to meters: a complete conversion guide (with tables)

The exact conversion, the mental-math shortcut, and a lookup table for the most-searched values. Plus when 1 foot does not equal 0.305 meters.

Jun 8, 20267 min
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Calculators

How to calculate BMI: formula, examples, and healthy ranges

Body Mass Index in plain English. The formula in both metric and imperial, worked examples, and what the categories really mean.

Jun 8, 20268 min
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Calculators

How much paint do I need? A room-by-room guide with examples

The formula, the coverage cheat sheet, and the room-size lookup table. Learn how to calculate gallons of paint for any room without buying too much or running short.

Jun 8, 202611 min
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PDF

How to merge PDFs without uploading them (2026 privacy guide)

Most online PDF mergers send your files to a remote server. Learn the techniques and tools that merge PDFs entirely in your browser, so signed contracts and tax returns never leave your device.

Jun 8, 20269 min
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Developer

Markdown explained: a complete guide for writers and developers

Markdown is the writing format that powers GitHub, blog platforms, Notion, and countless other tools. Learn the syntax, the GitHub Flavored extensions, common pitfalls, and when to use HTML instead.

May 4, 202612 min
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Developer

JWT explained: how JSON Web Tokens really work (with examples)

Demystify JSON Web Tokens. Learn what each part of a JWT means, how signing works, when to use them, and the security pitfalls that have leaked production tokens.

May 4, 202611 min
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Design

HEX, RGB, HSL, CMYK: every color format explained

Designers and developers work with colors in different formats. Learn what each one means, when to use it, and how to convert between them.

May 3, 20269 min
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Security

MD5 vs SHA-256: which hash should you use today?

Hashing is everywhere from passwords to file integrity to blockchains. Here is when to use MD5, SHA-1, SHA-256, and why the answer is almost always SHA-256.

May 3, 202610 min
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Developer

UUID v4 explained: a developer's guide to unique identifiers

What UUIDs are, why version 4 became the default, and when to use them instead of auto-increment database IDs.

May 3, 20269 min
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Developer

What is Base64 encoding? (with real-world examples)

Base64 turns any binary data into safe ASCII text. Learn how it works, when to use it, and why it is not encryption.

May 3, 20267 min
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Images

PNG vs JPG vs WebP: which image format should you use?

A practical breakdown of the three most common web image formats. When to use each, how they compress, and how to pick the right one for your project.

May 3, 20268 min