Learn
Guides that answer one question clearly, then point you to the right ToolHub utilities.
How to use AES Encrypt/Decrypt
Password-based AES-256-GCM demo via Web Crypto. A practical guide to AES Encrypt/Decrypt: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Age Calculator: a practical guide
Age in years, months, and days between two dates. A practical guide to Age Calculator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Working with Area Unit Converter
Convert area units like acres, hectares, and m². A practical guide to Area Unit Converter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Getting started with ASCII Code Converter
Convert text to character codes and back. A practical guide to ASCII Code Converter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
When to reach for Aspect Ratio Calculator
Simplify a ratio and scale to a target dimension. A practical guide to Aspect Ratio Calculator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Base64 Encode/Decode explained
Unicode-safe Base64 encode/decode for text and files locally. A practical guide to Base64 Encode/Decode: when it fits, how to get a reliable result, and the mistakes worth avoiding.
What is Base64?
Learn Base64 encoding—why APIs use it, how it differs from encryption, and how to encode or decode strings locally in your browser.
How to use Binary Text Converter
Convert text to binary and binary to text. A practical guide to Binary Text Converter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
BMI Calculator: a practical guide
BMI and weight category in metric or imperial. A practical guide to BMI Calculator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Working with Caesar Cipher
Adjustable-shift Caesar cipher, encode and decode. A practical guide to Caesar Cipher: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Getting started with Canonical URL Checker
Client-side canonical URL heuristics (no crawl). A practical guide to Canonical URL Checker: when it fits, how to get a reliable result, and the mistakes worth avoiding.
When to reach for Case Converter
Convert naming cases locally with smart word splitting. A practical guide to Case Converter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Character Frequency explained
Sorted character frequency report with percentages. A practical guide to Character Frequency: when it fits, how to get a reliable result, and the mistakes worth avoiding.
How to use Coin Flip
Flip virtual coins with fair, local randomness. A practical guide to Coin Flip: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Color and contrast: making palettes readable
How WCAG contrast ratios work, why lightness is not brightness, and how to build a palette that passes accessibility checks.
Color Converter: a practical guide
Convert HEX, RGB, and HSL locally with a live swatch. A practical guide to Color Converter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Working with Color Mixer
Blend two HEX colors with a mix ratio. A practical guide to Color Mixer: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Getting started with Color Picker
Sample image colors and copy hex/rgb locally. A practical guide to Color Picker: when it fits, how to get a reliable result, and the mistakes worth avoiding.
When to reach for Complementary Color Finder
Find complementary and split-complementary colors. A practical guide to Complementary Color Finder: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Compound Interest Calculator explained
Future value and interest earned from compounding. A practical guide to Compound Interest Calculator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
How to use Contrast Checker
Check WCAG AA/AAA contrast ratios for text colors. A practical guide to Contrast Checker: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Countdown Timer: a practical guide
Count down from a duration or to a target time. A practical guide to Countdown Timer: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Working with Cron Explainer
Turn cron expressions into readable schedules. A practical guide to Cron Explainer: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Reading and writing cron schedules
The five cron fields, common expression patterns, and the timezone and overlap issues that make scheduled jobs misfire.
Getting started with CSS Color Name Converter
Map CSS color names to HEX and back. A practical guide to CSS Color Name Converter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Working with CSV and tabular data
Quoting rules, delimiters, type loss, and how to move safely between CSV rows and JSON records.
Hashing explained: digests, checksums, and integrity
How cryptographic hash functions work, what a digest proves, and where SHA-256, HMAC, and password hashing each belong.
When to reach for Data Size Converter
Convert bytes, KB, MB, GB, TB, and binary units. A practical guide to Data Size Converter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Dice Roller explained
Roll virtual dice with fair, local randomness. A practical guide to Dice Roller: when it fits, how to get a reliable result, and the mistakes worth avoiding.
How to use Diff Checker
Line-level text diff with inline and side-by-side views. A practical guide to Diff Checker: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Discount Calculator: a practical guide
Final price and savings from a percent-off discount. A practical guide to Discount Calculator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Everyday financial math, done carefully
Percentages, VAT direction, compounding frequency, and loan amortisation—the arithmetic that quietly produces wrong numbers.
Working with Extract Emails
Pull deduplicated email addresses from text. A practical guide to Extract Emails: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Getting started with Find and Replace
Find and replace text with optional regex support. A practical guide to Find and Replace: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Focus sessions and honest time tracking
How countdowns, Pomodoro cycles, and stopwatches solve different problems—and why browser timers sometimes drift.
When to reach for GPA Calculator
Weighted 4.0-scale GPA from grades and credits. A practical guide to GPA Calculator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Gradient Generator explained
Build CSS linear-gradient strings with a live preview. A practical guide to Gradient Generator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
How to use Hash Generator
SHA-256/512 hashing for text and files via Web Crypto. A practical guide to Hash Generator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Hex Text Converter: a practical guide
Convert text to hex and hex to text. A practical guide to Hex Text Converter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Working with HMAC Generator
HMAC-SHA256/384/512 signing via Web Crypto. A practical guide to HMAC Generator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Getting started with HSL Adjuster
Tune hue, saturation, and lightness from a base HEX. A practical guide to HSL Adjuster: when it fits, how to get a reliable result, and the mistakes worth avoiding.
When to reach for HTML Encode/Decode
HTML entity encode/decode for markup and text locally. A practical guide to HTML Encode/Decode: when it fits, how to get a reliable result, and the mistakes worth avoiding.
HTTP headers you should recognise
Request and response headers that matter for debugging, caching, and security—plus how to read a raw header dump.
HTTP Headers Parser explained
Parse raw HTTP headers into a structured list. A practical guide to HTTP Headers Parser: when it fits, how to get a reliable result, and the mistakes worth avoiding.
How to use Image Compressor
Compress images locally with quality and size controls. A practical guide to Image Compressor: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Image Cropper: a practical guide
Crop images with accessible numeric controls. A practical guide to Image Cropper: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Working with Image Format Converter
Convert images to PNG, JPEG, or WebP locally. A practical guide to Image Format Converter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Image optimisation for the web
Choosing a format, sizing for the layout, and compressing without visible damage—an order of operations that saves the most bytes.
Getting started with Image Resizer
Resize images by size or percent, locally. A practical guide to Image Resizer: when it fits, how to get a reliable result, and the mistakes worth avoiding.
When to reach for JSON CSV Converter
Convert JSON arrays to CSV and back locally. A practical guide to JSON CSV Converter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
JSON Formatter explained
Format, validate, and minify JSON locally in your browser. A practical guide to JSON Formatter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
How to use JSON Minifier
Minify JSON locally into a compact single-line string. A practical guide to JSON Minifier: when it fits, how to get a reliable result, and the mistakes worth avoiding.
JSON Validator: a practical guide
Validate JSON locally with clear syntax error messages. A practical guide to JSON Validator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Working with JSON YAML Converter
Convert JSON and YAML both ways in your browser. A practical guide to JSON YAML Converter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
What is JSON?
Learn what JSON is, why APIs use it, common syntax rules, and which ToolHub utilities help you format and validate payloads locally.
Getting started with JWT Decoder
Inspect JWT header and payload locally—no signature verify. A practical guide to JWT Decoder: when it fits, how to get a reliable result, and the mistakes worth avoiding.
What is JWT?
Understand JSON Web Tokens—header, payload, signature—and how to inspect claims locally without treating decoding as verification.
When to reach for Keyword Density Analyzer
Local text stats and keyword density (no snake oil). A practical guide to Keyword Density Analyzer: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Length Unit Converter explained
Convert length units instantly in your browser. A practical guide to Length Unit Converter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
How to use Line Deduper
Remove duplicate lines from a list instantly. A practical guide to Line Deduper: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Line Sorter: a practical guide
Sort lines A–Z or Z–A instantly. A practical guide to Line Sorter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Working with List Randomizer
Shuffle or pick unique random entries from a list. A practical guide to List Randomizer: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Getting started with Loan Payment Calculator
Amortized monthly loan payment and total interest. A practical guide to Loan Payment Calculator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
When to reach for Local Notepad
Autosaving notepad that stays on your device. A practical guide to Local Notepad: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Markdown Preview explained
Live GFM preview with sanitized, XSS-safe rendering. A practical guide to Markdown Preview: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Markdown basics for documentation
Core Markdown syntax, GitHub-flavoured extensions, and when to drop into HTML—plus the sanitisation rule that matters.
How to use Meta Tag Preview
SERP-style meta title and description preview. A practical guide to Meta Tag Preview: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Number Base Converter: a practical guide
Convert bin/oct/dec/hex locally with BigInt. A practical guide to Number Base Converter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Summary statistics without misleading yourself
Mean, median, mode, spread, and percentages—which summary to report and how each one hides a different part of the data.
Working with Open Graph Preview
OG card layout mocks and meta tag export. A practical guide to Open Graph Preview: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Getting started with Palette Generator
Generate complementary, analogous, and triadic palettes from a base HEX. A practical guide to Palette Generator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
When to reach for Password Generator
Secure local password generator with strength meter. A practical guide to Password Generator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Password security that actually helps
Why length beats complexity rules, how entropy is estimated, and what to do with generated secrets after you copy them.
Password Strength Checker explained
Local entropy and checklist-based password strength check. A practical guide to Password Strength Checker: when it fits, how to get a reliable result, and the mistakes worth avoiding.
How to use PDF Merger
Merge PDFs locally with full order control. A practical guide to PDF Merger: when it fits, how to get a reliable result, and the mistakes worth avoiding.
PDF Metadata Viewer/Editor: a practical guide
View and edit basic PDF metadata locally. A practical guide to PDF Metadata Viewer/Editor: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Working with PDF Splitter
Extract PDF page ranges locally with validation. A practical guide to PDF Splitter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
PDF workflows without uploading files
How merging, splitting, and metadata edits work in the browser, and what a PDF still reveals after you share it.
Getting started with PEM Decoder
Inspect PEM structure and Base64 body locally. A practical guide to PEM Decoder: when it fits, how to get a reliable result, and the mistakes worth avoiding.
When to reach for Percentage Calculator
Percent of, percent-of-total, and percent change. A practical guide to Percentage Calculator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Pomodoro Timer explained
Focus with automatic Pomodoro work/break cycles. A practical guide to Pomodoro Timer: when it fits, how to get a reliable result, and the mistakes worth avoiding.
How to use Prime Number Checker
Check primality and list primes up to a limit. A practical guide to Prime Number Checker: when it fits, how to get a reliable result, and the mistakes worth avoiding.
QR Code Generator: a practical guide
Create PNG/SVG QR codes locally—no API. A practical guide to QR Code Generator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Working with Query String Parser
Parse and build URL query strings safely, client-side. A practical guide to Query String Parser: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Getting started with Random Color Generator
Generate random HEX colors with crypto randomness. A practical guide to Random Color Generator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
When to reach for Random Number Generator
Generate random integers in any range, locally. A practical guide to Random Number Generator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Random String Generator explained
Generate random strings with custom character sets. A practical guide to Random String Generator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Randomness and entropy in the browser
The difference between cryptographic randomness and Math.random(), how entropy is measured, and when each source is appropriate.
How to use Reading Time Calculator
Estimate minutes-to-read from word count and WPM. A practical guide to Reading Time Calculator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Regex Tester: a practical guide
Test regex patterns with flags, highlights, and safe timeout protection. A practical guide to Regex Tester: when it fits, how to get a reliable result, and the mistakes worth avoiding.
What is Regex?
Learn regular expressions—what they are good for, when parsers are safer, and how to test patterns locally without pasting sensitive data.
Working with Remove Empty Lines
Strip blank and whitespace-only lines instantly. A practical guide to Remove Empty Lines: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Getting started with Remove Line Breaks
Join wrapped lines into flowing paragraphs. A practical guide to Remove Line Breaks: when it fits, how to get a reliable result, and the mistakes worth avoiding.
When to reach for Robots.txt Generator
Form-based robots.txt builder with download. A practical guide to Robots.txt Generator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Roman Numeral Converter explained
Convert numbers to and from Roman numerals. A practical guide to Roman Numeral Converter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
How to use ROT13 Cipher
Classic ROT13 letter-shift cipher, encode = decode. A practical guide to ROT13 Cipher: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Security Headers Analyzer: a practical guide
Check for missing common security response headers. A practical guide to Security Headers Analyzer: when it fits, how to get a reliable result, and the mistakes worth avoiding.
SEO metadata that earns the click
Titles, descriptions, canonical tags, robots directives, and social cards—what each one controls and how they interact.
Working with Sitemap XML Generator
Build basic sitemap XML from a URL list. A practical guide to Sitemap XML Generator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Getting started with Slug Generator
URL slugify with diacritic stripping, locally. A practical guide to Slug Generator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
When to reach for Speed Unit Converter
Convert speed units like mph, km/h, and knots. A practical guide to Speed Unit Converter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Statistics Calculator explained
Count, mean, median, mode, and stdev from a list. A practical guide to Statistics Calculator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
How to use Stopwatch
Time tasks with a start/stop/lap stopwatch. A practical guide to Stopwatch: when it fits, how to get a reliable result, and the mistakes worth avoiding.
SVG Viewer: a practical guide
Sanitize, preview, and clean SVG locally. A practical guide to SVG Viewer: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Working with Temperature Converter
Convert Celsius, Fahrenheit, and Kelvin instantly. A practical guide to Temperature Converter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Text cleanup workflows that scale
A repeatable order for trimming, deduplicating, sorting, and replacing text so cleanup steps stop undoing each other.
Getting started with Text Repeater
Repeat text N times with an optional separator. A practical guide to Text Repeater: when it fits, how to get a reliable result, and the mistakes worth avoiding.
When to reach for Text Reverser
Reverse text, lines, or words instantly. A practical guide to Text Reverser: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Timestamp Converter explained
Convert Unix timestamps and dates with timezone display. A practical guide to Timestamp Converter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Timestamps, epochs, and timezones
Unix time, seconds versus milliseconds, UTC offsets, and the daylight-saving edge cases that break scheduled work.
How to use Tint Shade Generator
Generate tints and shades from a base HEX color. A practical guide to Tint Shade Generator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Tip Calculator: a practical guide
Tip amount, total, and per-person bill split. A practical guide to Tip Calculator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Unit conversion without the rounding traps
Why unit conversions go wrong—ambiguous unit names, offset scales, decimal versus binary prefixes—and how to keep results honest.
Working with Unsigned JWT Builder
Build unsigned JWTs for learning—never for production. A practical guide to Unsigned JWT Builder: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Getting started with URL Encode/Decode
URL percent-encoding with component and URI modes locally. A practical guide to URL Encode/Decode: when it fits, how to get a reliable result, and the mistakes worth avoiding.
When to reach for UUID Generator
Generate UUID v4 and v7 IDs locally with bulk output. A practical guide to UUID Generator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
What is a UUID?
Learn what UUIDs are, how versions differ (especially v4 vs v7), and how to generate identifiers locally without a server.
VAT Calculator explained
Add or remove VAT and see net/gross amounts. A practical guide to VAT Calculator: when it fits, how to get a reliable result, and the mistakes worth avoiding.
How to use Volume Unit Converter
Convert volume units for cooking, science, and more. A practical guide to Volume Unit Converter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Weight Unit Converter: a practical guide
Convert weight and mass units locally. A practical guide to Weight Unit Converter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Working with Whitespace Trimmer
Trim and normalize whitespace in text instantly. A practical guide to Whitespace Trimmer: when it fits, how to get a reliable result, and the mistakes worth avoiding.
Getting started with Word Counter
Live word, character, sentence, and line counts. A practical guide to Word Counter: when it fits, how to get a reliable result, and the mistakes worth avoiding.
When to reach for Yes/No Generator
Get a weighted random Yes or No answer. A practical guide to Yes/No Generator: when it fits, how to get a reliable result, and the mistakes worth avoiding.