Articles & Guides
Practical how-tos, tips, and tutorials to help you get more from our tools.
92 articles · Page 5 of 10
Email Deliverability Guide: Why Emails Land in Spam and How to Fix It
Understand SPF, DKIM, DMARC, and sender reputation — the technical and content factors that determine whether your emails reach the inbox.
Game Theory Explained: The Prisoner's Dilemma and Why Cooperation Is Hard
A practical introduction to game theory — Nash equilibrium, the Prisoner's Dilemma, Tit-for-Tat, and why rational actors often fail to cooperate even when it benefits everyone.
BMI Calculator — How to Calculate Your Body Mass Index
Learn how to calculate BMI, what your result means, and the limitations of BMI as a health metric. Use our free BMI calculator for instant results.
Freelancer Finance Guide: Invoices, Taxes, and Managing Irregular Income
A practical financial guide for freelancers and independent contractors — covering invoicing, tax estimation, retirement savings, and building financial stability on variable income.
How to Convert JPG to PDF for Free — No Sign-Up, No Watermark
Convert one or multiple JPG images to a single PDF file in seconds. Free, no account required, no watermark. Works in your browser on any device.
How to Convert Video to GIF for Free — No Software Needed
Convert any video clip to an animated GIF instantly in your browser. Free, no sign-up, no watermark. Works with MP4, WebM, MOV, and AVI files.
CSS Developer Tools: Generate Gradients, Shadows, Convert Units, and Check Accessibility
A hands-on guide to browser-based CSS tools — build gradients and box shadows visually, convert between px/rem/em, check WCAG color contrast, generate color palettes, and convert CSS to Tailwind classes.
Financial Calculators: Plan Loans, Savings, Investments, and Debt Payoff in Your Browser
A practical guide to free browser-based financial calculators — loan amortization, savings goals, compound interest, debt snowball, salary take-home pay, and more — no spreadsheet required.
How to Convert HEIC to JPG for Free — iPhone Photos on Any Device
Convert HEIC and HEIF photos from iPhone to JPG instantly. No software, no sign-up, no upload to server. Works in your browser on Windows, Mac, and Android.
JSON & Data Tools: Format, Validate, Convert, and Query JSON Without Code
A complete guide to browser-based JSON tools — format and validate JSON, generate TypeScript interfaces, convert to CSV or SQL, build Zod schemas, compare JSON diffs, and run JSONPath queries.