Guides · Articles · Practice
Learn the method.
Then apply it.
Guides teach how something works. Articles open the wider idea—technology, science, programming, and learning. When you want to try it, a percentage, a unit, or a piece of JSON, you can do that here.
Practice happens in the browser when it can. No account required.
Guides
Start with a guide
Practical explanations that teach the method—then link to the SmartKitio tool that applies it.
Mathematics & calculators
How to Calculate Percentages
The three percentage problems people meet most often, with formulas and worked examples.
Read the guideMathematics & calculators
Percentage Increase vs Percentage Decrease
How to compute both directions correctly, and why reversing a percent change is not symmetric.
Read the guideMathematics & calculators
How to Calculate BMI
The Body Mass Index formulas in metric and imperial units, adult categories, and important limits.
Read the guideUnits & conversions
Metric vs Imperial Units: Complete Guide
Why two measurement systems persist, how base units relate, and which everyday conversions matter most.
Read the guide
Articles
Ideas worth understanding
Broader articles on technology, AI, programming, science, and learning, with examples you can check.
Programming
Encoding vs Encryption: What's the Difference?
Encoding, encryption, hashing, and compression solve different problems. Confusing them—especially Base64 with secrecy—creates real security failures.
6 min read · 2026-10-04
Read the article
Technology
How a Web Browser Actually Works
From typing a URL to painting pixels—what the browser is doing under the calm address bar.
8 min read · 2026-10-04
Read the article
AI
How Large Language Models Actually Work
From training data and tokenization through transformers, attention, and inference—what “next-token prediction” really means under the hood.
9 min read · 2026-10-04
Read the article
Education
How Spaced Repetition Works
Why reviewing just before you forget beats cramming—and how forgetting curves, retrieval, and expanding intervals fit into a practical schedule.
7 min read · 2026-10-04
Read the articleTools
Popular tools
Ready-to-use calculators, converters, and utilities—linked from guides and articles when a deeper explanation helps.
Calculator
Percentage
Work out a percentage of a number, the reverse (“X is what percent of Y?”), or how much a value has gone up or down.
Calculator
Loan
Estimate equal installments on an amortizing loan, plus total interest, from the amount borrowed, annual rate, and length in years.
Image Tool
Compress
Make photos smaller for email, websites, or upload limits by lowering the encoding quality. You can check the result and its file size before downloading.
Image Tool
Resize
Change an image to an exact width and height in pixels, for profile pictures, product listings, or upload requirements.
PDF Tool
Merge
Combine several PDF files into a single document, in the order you add them, without uploading them anywhere.
PDF Tool
JPG→PDF
Combine one or more JPG or PNG images into a PDF, one image per page, for example to send scanned receipts or photos as a single document.
Converter
Length
Convert between metric lengths (millimeters to kilometers) and the international units used in the US and UK (inches, feet, yards, miles). Every unit is defined exactly in meters, so results are exact before rounding.
Converter
Weight
Convert mass between kilograms, grams, milligrams, pounds, and ounces. The pound and ounce are the international avoirdupois units, which are defined exactly in kilograms.
Categories
Tool families
When you are ready to calculate or convert, open a family—or search by name.
Calculators
Percentages, loans, BMI, dates, and everyday math — with the formula in view.
Image Tools
Compress, resize, crop, and convert images in the browser. The file is not uploaded to SmartKitio.
PDF Tools
Merge, split, convert, and inspect PDFs in your browser when possible.
Converters
Length, weight, energy, pressure, and more — instant unit conversion in your browser.
Text Tools
Count words, change case, clean pasted text, and sort lines. Your text stays on this device.
Developer Tools
JSON, Base64, JWT, regex, UUIDs, and formatters. Local processing, no account required.
Security Tools
Passwords, hashes, JWT decode, and encoding. What you type stays in the browser.
SEO Tools
Meta tags, Open Graph, robots.txt, slugs, UTM links, and social previews.
Design Tools
Colors, palettes, contrast, and copy-ready CSS generators.
Everyday Tools
Timers, dice, QR codes, and simple daily cost tools.
How it fits together
How SmartKitio works
Use a tool for a result. Read a guide when you need the method. Open an article when you want the bigger idea. Each layer links to the others when it genuinely helps.
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Tools
Open a calculator, converter, or utility and get a result you can check. When a tool can run locally, what you type stays on this device.
Browse tools - 02
Guides
Learn the method: what the idea means, the formula or steps, a worked example, and the mistakes that throw the result off.
Read guides - 03
Articles
Go wider—how a browser loads a page, how JSON is structured, or why encoding is not the same thing as encryption.
Read articles