Practical tips, in-depth guides, and resources to help you build better on the web.
Barcode types explained: UPC-A, EAN-13, Code 128, Code 39, Interleaved 2 of 5 and QR codes. Learn how each format works, when to use it, and how to create one free.
How to make a color wheel step by step: draw the 12 colors, mix primaries into secondaries and tertiaries, use a free blank template, plus creative color wheel project ideas.
The hair color wheel explained: use complementary colors to neutralize brassy, orange, yellow and green hair. Includes a color-correction chart, level guide and toning tips.
Schema markup examples with copy-paste JSON-LD code for FAQ, Article, LocalBusiness, Product, Organization, Breadcrumb and Review structured data — plus how to add and validate it.
How to calculate a tip fast: the simple tip percentage formula, a 15/18/20% tip chart, and how much to tip at restaurants, hair salons, tattoo artists, movers and delivery.
How to reverse image search on iPhone, Android and desktop. Step-by-step guides for Google Lens, Google Images, TinEye, Yandex and Pinterest — plus how to catch a catfish.
How to find and replace in Word, Excel, Google Docs, Notepad and more. Learn the Ctrl+H find and replace shortcut, wildcards, regular expressions, and how to replace text in bulk online.
Learn how to calculate BMI with the body mass index formula for metric and imperial units. Includes BMI chart, categories, calculation examples, limitations, and what your BMI score actually means.
Learn how to calculate discount percentage, sale price, and original price with simple formulas. Covers stacked discounts, tax calculation, common discount tables, and real-world examples.
The complete .htaccess redirect guide. Learn 301 and 302 redirects, URL rewriting with mod_rewrite, HTTP to HTTPS, www to non-www, SEO-friendly URLs, caching rules, and common mistakes to avoid.
The complete regex cheat sheet with metacharacters, quantifiers, character classes, lookaheads, flags, and common patterns for email, URL, and phone number validation — with copy-ready examples.
Learn how to calculate area for every shape — rectangle, triangle, circle, trapezoid, parallelogram, and irregular shapes. Step-by-step formulas, examples, and unit conversions.
Learn how Base64 encoding works, why it converts binary to text, and when to use it. Covers the algorithm, JavaScript btoa/atob, Python, PHP, data URIs, URL-safe variants, and real-world examples.
The complete guide to HTML meta tags for SEO. Learn essential meta tags, Open Graph tags, Twitter Cards, canonical tags, robots directives, and structured data to boost your search rankings and social sharing.
Learn the compound interest formula A = P(1 + r/n)^(nt), how to calculate compound interest step by step, the Rule of 72, compounding frequency effects, and real-world examples for savings, loans, and investments.
Learn how to calculate percentage with simple formulas and real-world examples. Covers percentage of a number, percentage change, increase and decrease, conversions between decimals and fractions, and common mistakes to avoid.
Learn how to create professional PDF invoices online for free. Step-by-step guide covering invoice elements, payment terms, tax calculations, and free invoice generator tools.
Understand Unix timestamps, epoch time, and how to convert between human-readable dates and timestamps in JavaScript, Python, PHP, and SQL with practical examples.
Learn how to optimize images for the web — choose the right format (WebP, AVIF, JPEG, PNG), compress without losing quality, implement lazy loading, and boost Core Web Vitals.
Learn how URL encoding works, why percent-encoding exists, which characters must be encoded, and the difference between encodeURI and encodeURIComponent with practical examples.
The complete Markdown cheat sheet with headings, lists, links, images, code blocks, tables, and advanced formatting — with examples you can copy and use.
JSON vs CSV: understand the strengths and limitations of each data format, when to use which, and how to convert between them instantly.
Learn how to create strong passwords, understand entropy, avoid common mistakes, and use two-factor authentication to protect your accounts from modern attacks.
Master WCAG color contrast requirements for web accessibility. Learn AA and AAA standards, calculate contrast ratios, and build accessible color palettes.
Learn how CSS minification works, why it matters for Core Web Vitals, and how to minify CSS, HTML, and JavaScript to make your website load up to 60% faster.
A deep dive into UUID versions, when to use each, and how v7 combines timestamps with randomness for sortable unique IDs.