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Guides and how-tos for every tool on belun.app.
Morse Code in 2026: How It Works and How to Read It How Morse timing actually works, why E is a single dot, why SOS was chosen, and how to translate and hear dots and dashes in your browser. How to Sort Lines of Text Online (and Why 10 Sorts Before 9) A practical guide to sorting lists in the browser — alphabetical, numeric, and by length, plus how to strip duplicates that uniq misses. How to Format and Beautify HTML in the Browser (Free) Why HTML indentation gets messy, how a formatter handles void tags and script blocks, and how to prettify or minify markup with nothing to install. How to Format and Validate XML in the Browser (Free) Why XML formatting matters, what well-formed really means, and how to pretty-print, validate, and minify XML without installing anything. Image to Base64: When Data URIs Help and When They Hurt What Base64 image encoding is, how data URIs work in HTML and CSS, and the size trade-off you should know before inlining. Text to Speech in the Browser: A Practical Guide How free browser text to speech works, which voices you get, and when reading text aloud beats reading it on screen. How to Calculate a Discount (and Why Stacked Coupons Lie) Percent-off maths in plain English: work out a sale price by hand, spot fake discounts, and find out why 20% off twice is never 40% off. How to Merge PDFs Without Uploading Them Anywhere Most free PDF sites want your files on their servers first. Here's what that costs you, and how to merge PDFs entirely offline in a browser tab. Scientific Calculator: 3 Mistakes That Give You Wrong Answers Degree vs radian mode, the −2² trap, and what the memory keys are actually for. How to type expressions a scientific calculator can't misread. How Compound Interest Works: Formula, Examples, Rule of 72 What compounding frequency actually changes, why starting early beats saving more, and how to check the math behind your savings yourself. How Many Calories Do You Need? TDEE and BMR Explained What BMR and TDEE actually mean, how the Mifflin-St Jeor equation works, and how to pick a realistic calorie target for losing or gaining weight. Word Frequency Analysis: Find Overused Words in Any Text How counting word frequency helps you spot repetition, check keyword density, and tighten your writing — with a free browser tool. How Much to Tip: Percentages, Countries, and Splitting the Bill What to tip at restaurants, bars, and for delivery, how customs differ by country, and the fastest way to split a bill with tip among friends. HTML Entities Explained: When and Why to Escape Characters What HTML entities are, which characters to escape, how encoding stops XSS, and how to encode or decode entities free in your browser. Time Zone Converter Guide: Convert and Compare Times Worldwide How time zones and daylight saving really work, plus a fast way to pick a meeting time that works for people in three different countries. CSS Gradients Explained: Linear, Radial, and Color Stops How CSS gradients actually work — the angle trap, color stops, radial shapes, and the transition gotcha — with copy-paste code. How to Compress Images Without Wrecking the Quality A practical guide to shrinking JPEG, PNG, and WebP files, which quality settings to use, and why WebP usually wins on size. What Your Browser Knows About Where You Are How the browser Geolocation API works, what each field in the response means, and why accuracy swings from a few metres to several kilometres. The Online Notepad That Remembers: Local-First Notes Explained How a browser notepad autosaves without an account, what local storage can and can't keep, and when you should back your notes up. What Is My IP Address, and Who Can See It? A plain-English look at your public IP address: what it reveals about you, why it keeps changing, and how to hide it when you want to. What Is My IP Address? Public IP, Geolocation, and ISP Explained How public IP addresses work, what IP geolocation can and cannot reveal, and how to look up any IPv4 or IPv6 address for free. Online Stopwatch and Timer: Laps, Presets, and When to Use Each How a browser stopwatch and countdown timer differ, why lap splits matter, and practical ways to use both for workouts, work, and the kitchen. CSV to JSON: Delimiters, Quotes, and the Leading-Zero Trap How header rows become keys, why auto-detection beats guessing the delimiter, and the type-coercion gotcha that eats your ZIP codes. How to Convert SVG to PNG (and When You Should) A practical guide to turning SVG vectors into crisp PNG images in the browser — scaling, transparency, and when each format wins. Cron Expressions Explained: How to Read a Crontab Schedule The five cron fields, steps and ranges, the day-of-month/day-of-week gotcha, and a set of schedules you can copy straight into your crontab. How to Decode a JWT (and What Every Claim Actually Means) A practical guide to JSON Web Tokens — the three parts, the standard claims, and how to read a token safely without leaking it. JSON to CSV: How to Flatten an API Response into a Spreadsheet What converts cleanly, how nested objects and missing keys are handled, and the delimiter trap that breaks CSV in Excel. HTML to Markdown: When and Why You'd Convert the Other Direction Why people convert HTML back to Markdown, what survives the round trip, and the edge cases that trip up most converters. How a Random Number Generator Works (and When to Use One) What makes a random number generator fair, why crypto randomness beats Math.random(), and practical uses from raffles to sampling. How to Calculate Loan Payments: Amortization and Real Examples Understand how monthly payments and amortization work, with worked examples for car loans and mortgages — plus how to compare loans before you sign. How to Crop an Image Online Without Uploading It Crop photos to the right shape for any platform — and why doing it in the browser keeps your images private. A practical guide with exact ratios. Reverse Text Online: Letter and Word Reversal Explained How text reversal works, what it's used for, and how to flip any string in seconds with a free browser tool. Flesch Reading Ease and Grade Level Explained — With a Free Checker What the Flesch-Kincaid readability scores mean, why they matter for web writing, and how to use them to cut through dense text. Text to Binary: How ASCII Encoding Turns Characters into Bits A practical guide to how computers store text as binary, how to read binary-encoded strings by hand, and when you'd actually need to do this. Aspect Ratio Calculator: Scale Images and Video Without Distortion How to find equivalent dimensions when resizing images, videos, or UI elements — with examples for 16:9, 4:3, and other common ratios. Binary, Octal, Decimal, and Hex: A Developer's Guide to Number Bases Why computers use binary and hex, how to convert between number bases, and when each system shows up in real-world code. Regular Expressions Explained: Patterns, Flags, and Practical Examples Learn how regular expressions work in JavaScript: flags, character classes, anchors, and common patterns for emails, URLs, and phone numbers. Markdown to HTML: A Practical Guide for Writers and Developers How Markdown-to-HTML conversion works, what syntax is supported, and when a browser-based converter beats a build tool. How to Minify CSS: Tools, Techniques, and What Actually Matters A practical guide to CSS minification — what it removes, how much it saves, and when manual tools make sense over build pipelines. How to Resize Images Online Without Losing Quality A practical guide to image resizing: right dimensions for email, social media, and web — plus how a free browser-based tool works with no upload needed. Unix Timestamps Explained: What They Are and How to Convert Them A practical guide to Unix timestamps — what epoch time means, seconds vs milliseconds, timezones, and how to convert between timestamps and dates. How to Calculate Your Exact Age in Years, Months, and Days A practical guide to age calculation — the exact formula, leap year edge cases, and how to find how many days you've lived. BMI Calculator: How to Calculate Body Mass Index and What It Means A practical guide to BMI — the formula, healthy ranges, limitations, and how to use the calculator for metric and imperial units. How to Create a QR Code for Free (and What to Put In It) A practical guide to QR codes — what to encode, how to create them instantly in the browser, and tips for printing and sharing. How to Convert Units Online: Length, Weight, Temperature & Volume A practical guide to unit conversions — metric vs imperial, common mistakes, and when each unit type matters. How to Compare Two Texts and Spot the Differences Instantly A practical guide to text diffing — use cases, how line-level comparison works, and why browser-based tools keep your data private. Lorem Ipsum: History, Uses, and How to Generate It Free A practical guide to Lorem Ipsum placeholder text — where it comes from, when to use it, and how to generate custom paragraphs instantly for free. UUID v4 Explained: What It Is and When to Use It A practical guide to UUID v4 — how it works, when to use it as a primary key, and how it compares to other unique ID strategies. Hash Functions Explained: MD5, SHA-1, SHA-256, and SHA-512 A practical guide to cryptographic hash functions — what they are, when to use each one, and why MD5 and SHA-1 are no longer safe for security-critical work. Color Codes Explained: HEX, RGB, HSL, and HSV A practical guide to color formats used in web design and development, and how to convert between them instantly. How to Create a Strong Password (and Never Forget It) A practical guide to password strength, entropy, and why a random password generator is safer than anything you can invent yourself. How to Calculate Percentages: Formulas, Examples & Free Tool A practical guide to the four most common percentage problems — with formulas, worked examples, and a free online calculator that updates as you type. WebP vs JPEG vs PNG: When to Use Each Format A practical guide to image formats and how a free online converter can help you pick the right one for photos, graphics, and web use. How to Catch Spelling Mistakes Before They Cost You A practical guide to common spelling errors in English and how a free online spell checker can help you find them instantly. How to Check for Plagiarism Online for Free A practical guide to detecting duplicate content, understanding similarity scores, and avoiding plagiarism in essays and documents. Text Case Styles Explained: camelCase, snake_case, kebab-case & More A practical guide to the most common text case styles — when to use each one and how to convert between them instantly. 5 Grammar Mistakes a Professional Engine Catches That You Might Miss A practical guide to common English grammar errors — and how Harper, an open-source grammar engine, detects them automatically. Character Count Online: Why It Matters and How to Do It Right A practical guide to character counting for social media, SEO, SMS, and coding — with tips on platform limits and how different tools count. DNS Records Explained: A, MX, TXT, CNAME, NS and How to Look Them Up A practical guide to DNS record types, what each one does, and how to query them instantly without installing any tools. JSON Formatting & Validation: A Developer's Practical Guide Why JSON formatting matters, common pitfalls, and how to validate JSON for free in your browser — no tools to install. How to Calculate Triangle Area, Angles & Perimeter: Complete Guide Understand Heron's formula, the Law of Cosines, and triangle classification — with a free online calculator that shows all results instantly. URL Encoding Explained: When, Why, and How to Encode URLs A clear guide to percent-encoding — what it is, when you need it, and how to encode and decode URL strings for free in your browser. How to Count Words Online for Free (and Why It Matters) A practical guide to word counting for students, writers, and developers — with tips on character limits, reading time, and more. Base64 Encoding Explained: What It Is and When to Use It A beginner-friendly guide to Base64 — how it works, real-world use cases, and how to encode or decode strings for free in your browser.