Guides
Short, practical explanations of the ideas behind our tools, with examples you can try.
73 guides found
Developer
How to Read a Cron Expression (With Examples)
Learn what the five fields of a cron expression mean, how */5 and 1-5 work, and see common schedules explained clearly.
2 min read
Developer
How to Fix the Most Common JSON Errors
Trailing commas, single quotes, unquoted keys and more. Learn to read a JSON error message and fix invalid JSON quickly.
1 min read
Developer
Regex Cheat Sheet for Beginners
A plain-English guide to regular expressions: character classes, quantifiers, groups, flags and examples you can test.
2 min read
Developer
HTTP Status Codes Explained: The Ones You Actually Need
What 200, 301, 404, 500 and other HTTP status codes mean, how 401 differs from 403, and which code to return from your API.
2 min read
Developer
Base64 Explained: What It Is and When to Use It
How Base64 encoding works, why it makes data 33% larger, where it is used (data URIs, JWTs, email) and why it isn't encryption.
1 min read
Security
How to Create a Strong Password (and Keep It Safe)
Why length beats complexity, how long a password should be, how passphrases work and how developers should store passwords.
2 min read
Developer
Linux File Permissions and chmod Explained
Understand read, write and execute permissions, what 755 and 644 mean, and how to use chmod with octal and symbolic modes.
2 min read
Web & SEO
px vs rem vs em: Which CSS Unit Should You Use?
The difference between px, rem and em in CSS, how to convert between them, and when each one is the right choice.
1 min read
Developer
Subnet Masks and CIDR Notation Explained
What /24 and 255.255.255.0 mean, how to count hosts in a subnet, and how to split a network into smaller ones.
1 min read
Developer
Unix Timestamps Explained
What a Unix timestamp is, the difference between seconds and milliseconds, how time zones fit in, and the Year 2038 problem.
2 min read
Images
How to Compress Images Without Losing Quality
Make photos and graphics much smaller for your website or email. Learn which format and quality setting to use, and when to resize first.
2 min read
Images
PNG vs JPG vs WebP: Which Image Format Should You Use?
A plain-English comparison of PNG, JPG and WebP: file size, transparency, quality, and which one fits photos, logos and screenshots.
2 min read
Images
How to Make a Favicon for Your Website
Which favicon files you need, what sizes they should be, and the HTML to add so every browser, phone and bookmark shows your icon.
1 min read
Web & SEO
How QR Codes Work and How to Make a Good One
What a QR code stores, what the error correction levels mean, and the rules that make a code scan every time.
2 min read
Developer
UUID, ULID and NanoID: Which Unique ID Should You Use?
How UUID v4, UUID v7, ULID and NanoID differ, why sortable IDs help databases, and how to pick the right one for your project.
1 min read
Security
What Is a Hash Function? MD5, SHA-256 and Bcrypt Explained
Learn what hashing does, why the same input always gives the same hash, which algorithms are still safe, and why passwords need bcrypt.
1 min read
Security
How to Decode a JWT and Read Its Claims
A JSON Web Token has three parts. Learn what each part holds, what exp and iat mean, and why decoding a token isn't the same as trusting it.
1 min read
Developer
JSON vs YAML vs XML vs CSV: Choosing a Data Format
The strengths and weaknesses of JSON, YAML, XML and CSV, with simple advice on which to use for APIs, config files and spreadsheets.
1 min read
Web & SEO
How to Write a robots.txt File (With Examples)
What robots.txt does and doesn't do, how Disallow and Allow rules work, how to add your sitemap, and mistakes that can hide your whole site.
1 min read
Web & SEO
How to Build UTM Links and Track Your Campaigns
What the five UTM parameters mean, which ones are required, naming rules that keep reports clean, and mistakes that split your data.
1 min read
Web & SEO
SEO Meta Tags Explained: Title, Description and Open Graph
The meta tags that decide how your page looks in Google and when shared on social media, with length limits and examples you can copy.
1 min read
Writing & text
How to Improve the Readability of Your Writing
What a readability score measures, how the Flesch formula works, and practical ways to make your writing clearer and easier to scan.
2 min read
Money, health & time
How Loan Payments Are Calculated (With a Worked Example)
See the formula behind a monthly loan payment, how interest and principal split over time, and how extra payments save money.
1 min read
Money, health & time
Compound Interest Explained: How Money Grows Over Time
What compound interest is, how the formula works, why compounding frequency matters, and how the Rule of 72 gives a quick estimate.
1 min read
Money, health & time
BMI Explained: What It Means and What It Does Not
How body mass index is calculated, what the standard categories are, and why BMI is only a rough screening tool and not a diagnosis.
1 min read
Images
Aspect Ratios Explained: 16:9, 4:3, 1:1 and Resizing
What an aspect ratio is, the common ones for video, photos and social media, and the simple maths to resize without distorting your image.
1 min read
Money, health & time
The Pomodoro Technique: How to Focus in 25-Minute Sprints
How the Pomodoro Technique works, the exact steps, how to adjust the timings, and what to do when interruptions get in the way.
2 min read
Money, health & time
Time Zones, UTC and Daylight Saving: A Practical Guide
Why time zones cause bugs and missed meetings, what UTC is, how daylight saving shifts things, and rules for working across zones.
2 min read
Writing & text
Markdown Cheat Sheet: Syntax You Will Use Every Day
The Markdown basics in one page: headings, bold, lists, links, images, code and tables, with examples you can copy.
1 min read
Writing & text
How to Clean Up Text Copied From PDFs and Websites
Fix broken line breaks, double spaces and stray characters in copied text, then sort, number and tidy it in a few clicks.
2 min read
Writing & text
Title Case Rules: AP, APA, Chicago and MLA Compared
Which words to capitalize in a title, how the four main styles differ, and what to do with hyphens, colons and short words.
2 min read
Writing & text
How to Cite a Website, Book or Article in APA, MLA and Chicago
What each citation style needs, how the same source looks in APA, MLA and Chicago, and how in-text citations and reference lists work.
2 min read
Writing & text
Palindromes, Reversed Text and Morse Code Explained
What makes a palindrome, how reversed and mirrored text is used, how Morse code is timed, and when fancy Unicode text is a bad idea.
2 min read
Writing & text
Roman Numerals and Writing Numbers in Words
How Roman numerals work, how to read and write them, and the rules for spelling numbers out in words for cheques and documents.
2 min read
Writing & text
How to Type Emoji and Special Characters on Any Device
Keyboard shortcuts for emoji and symbols on Windows, Mac and phones, how Unicode and HTML entities work, and why some characters break.
1 min read
Writing & text
Lorem Ipsum and Placeholder Text: When and How to Use It
Where lorem ipsum comes from, why designers use it, when to use real sample data instead, and how to fill a design with realistic content.
1 min read
Writing & text
How to Type Faster and What Your WPM Really Means
How words per minute is measured, what a good typing speed is, and practical habits that raise speed and accuracy without strain.
1 min read
Writing & text
How to Proofread Your Writing by Listening to It
Why hearing your text read aloud finds mistakes your eyes skip, and how to use text to speech with other checks to polish a draft.
2 min read
Developer
Turn JSON or XML Into Classes (DTOs) in Java, C# and More
What a DTO is, how generated classes map JSON and XML, and the details to check before you trust a generated model.
1 min read
Developer
How to Format SQL So Anyone Can Read It
Simple formatting habits that make SQL queries easy to read and review, plus how to handle quotes and when a formatter helps.
1 min read
Web & SEO
HTML Entities, Formatting and Minifying Explained
When to escape characters in HTML, how formatting and minifying differ, and how much minifying HTML, CSS and JavaScript really saves.
1 min read
Developer
Base32 vs Base64: What the Difference Is and When to Use Each
How Base32 and Base64 work, why Base32 is longer but safer for people, and where each is used, from authenticator apps to data URLs.
1 min read
Developer
How Random Number Generators Work and Why Fair Picks Matter
The difference between ordinary and secure randomness, how to pick fairly without repeats, and what dice and coins really do.
2 min read
Security
How to Choose a Good Username (and Keep It Safe)
What makes a username memorable and safe, what personal details to leave out, and how to pair it with a strong password.
1 min read
Money, health & time
Notes and To-Do Lists That Actually Work
A simple system for capturing notes and tasks, keeping the list short, and staying focused, plus what to know about browser-based notes.
1 min read
Money, health & time
Week Numbers and Countdowns: ISO Weeks, Business Days and Time Left
How ISO and US week numbers work, why week 53 exists, how to count days and weekdays to a deadline, and where countdowns go wrong.
1 min read
Money, health & time
How to Calculate Hours Worked, Overnight Shifts and Pay
How to work out hours between clock times, take off breaks, convert minutes to decimal hours, and turn hourly pay into a yearly salary.
1 min read
Money, health & time
How to Calculate a Tip, Sales Tax and VAT
Easy ways to work out a tip and split a bill, and how to add or remove sales tax and VAT from a price without the common mistake.
1 min read
Money, health & time
Profit Margin vs Markup vs ROI: What Each Means
The difference between margin and markup, how to price from a target, how to convert between them, and how to read return on investment.
1 min read
Money, health & time
Savings Goals and Inflation: Planning Money That Keeps Its Value
How to work out how long a savings goal takes, how much to save each month, and how inflation quietly shrinks what your money can buy.
1 min read
Money, health & time
How to Calculate GPA: Scales, Weighted Courses and Final Grades
How GPA is worked out on 4.0 and 5.0 scales, what weighted GPA means, how to combine terms, and what you need on a final exam.
2 min read
Money, health & time
Mean, Median, Mode and Standard Deviation: A Plain Guide
What each average tells you, when the median beats the mean, how standard deviation measures spread, and when to use sample or population.
1 min read
Money, health & time
GCD, LCM and Fractions: How They Connect
How to find the greatest common divisor and least common multiple, and how they help you simplify and add fractions step by step.
1 min read
Money, health & time
How Many Calories Do You Need? BMR, TDEE and Weight Goals
What BMR and TDEE mean, how daily calories are estimated, how a calorie change relates to weight change, and the limits of any calculator.
1 min read
Money, health & time
How Pregnancy Due Dates Are Calculated
How a due date is worked out from the last period or conception, how cycle length changes it, and what the weeks and trimesters mean.
1 min read
Images
SVG vs PNG: When to Use Each and How to Shrink SVG Files
How vector SVG differs from PNG, when each is best, how to turn an SVG into a PNG at any size, and how to clean up and optimize SVG files.
2 min read
Images
What Is HEIC and How to Open iPhone Photos Anywhere
Why iPhones save photos as HEIC, why they won't open on some computers and sites, and how to convert them to JPG or PNG safely.
1 min read
Web & SEO
Barcodes Explained: EAN, UPC, Code 128 and Code 39
How the main barcode types differ, what the digits and check digit mean, tips for printing barcodes that scan, and how they compare to QR codes.
2 min read
Security
How Password Encryption Works (AES) and When to Use It
What AES encryption does, why a password becomes a key, how to protect a message or file, and what you can't recover if you forget the password.
2 min read
Security
Two-Factor Codes Explained: How TOTP Authenticator Apps Work
How the six-digit codes in authenticator apps are made, why they change every 30 seconds, what the secret key is, and how to set one up safely.
2 min read
Developer
SSH Keys and Key Pairs Explained: Which Type to Pick
What a public and private key pair is, how SSH keys let you sign in without a password, and how to choose between Ed25519, RSA and ECDSA.
2 min read
Security
How to Check a Download With a Checksum (and Why It Matters)
What a checksum is, how to compare a file against the one on a download page, which hash to trust, and what to do if the result doesn't match.
2 min read
Images
What Is EXIF Data in Photos and How to Remove It
Photos carry hidden details like where and when they were taken. Learn what EXIF data holds, why it matters for privacy, and how to strip it safely.
2 min read
Images
How to Watermark Photos Without Ruining Them
How to add a text or logo watermark to photos, where to place it, what opacity works, and why a watermark slows copying but doesn't stop it.
2 min read
Images
How to Hide Faces and Private Details in Photos Properly
When to use a black box, blur or pixelation, why text can sometimes be read back from a blur, and how to share screenshots and photos safely.
2 min read
Images
How to Make a Photo Collage That Looks Good
How to choose a layout, pick photos that fit together, set the spacing and shape, and save a collage at the right size for social media or print.
1 min read
Images
How to Make a Meme: Text, Fonts and What Makes It Work
How the classic top and bottom text meme works, how to place and style the words so they're readable, and what to check before you share one.
1 min read
Images
How to Pick a Color Palette From a Photo
How to build a color scheme from an image, how a palette is found, and how to use the colors in a design, a website or a room.
1 min read
Images
How to Make a Signature Image for Documents and Emails
How to draw or type a signature, save it as a transparent PNG, and use it on documents, plus what an image signature is and isn't worth legally.
1 min read
Money, health & time
How to Record Your Voice Online Without Installing Anything
Record a voice note, interview or practice talk right in your browser, with tips for clear sound, and how to save and share the file.
1 min read
Money, health & time
How to Record Your Screen for Free, No Download Needed
Record a window, a tab or your whole screen from the browser, with or without sound, and save the video. Includes tips for tutorials and bug reports.
1 min read
Money, health & time
How to Use Your Webcam to Take Photos and Record Video
Test your camera, take photos and record short videos in the browser. Includes fixes for a black picture, the wrong camera, and permission problems.
1 min read
Money, health & time
How to Trim, Fade and Convert Audio Files in Your Browser
Cut a sound file to the part you want, add fades, level the volume and save it as WAV. Covers ringtones, voice notes and podcast clips.
2 min read