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Free tools, useful references, and practical information.
Age Calculator
Calculate age in complete years, months, and days between two dates.
CalculatorsAspect Ratio Calculator
Calculate proportional image and video dimensions.
File ToolsAudio File Converter
Convert browser-supported audio files to WAV or MP3 locally.
Developer ToolsBase64 Encoder and Decoder
Encode Unicode text as Base64 or decode Base64 back to text.
CalculatorsBusiness Days Calculator
Count weekdays between dates with optional holiday exclusions.
Text ToolsCaesar Cipher Encoder and Decoder
Shift letters to encode or decode a classic Caesar cipher.
Text ToolsCase Converter
Convert text to lowercase, uppercase, title case, or sentence case in your browser.
Music ToolsChord and Scale Explorer
Explore common chord and scale formulas, notes, and piano positions.
GamesCoin Flip Simulator
Flip one or many virtual coins and review the result distribution.
Color ToolsColor Contrast Checker
Check two colors against WCAG text contrast thresholds.
Color ToolsColor Format Converter
Convert colors between HEX, RGB, and HSL formats.
Color ToolsColor Picker
Choose a color, build a small palette, and copy HEX, RGB, or HSL values.
CalculatorsCompound Interest Calculator
Estimate investment growth with regular monthly contributions.
ConvertersCooking Measurement Converter
Convert common cooking volume and weight measurements.
CalculatorsCoordinate Distance Calculator
Calculate distance, midpoint, direction, and angles between 2D or 3D points.
Time ToolsCountdown Date Calculator
See a live countdown to any local date and time.
Developer ToolsCron Expression Builder
Build standard five-field cron expressions with useful presets.
Developer ToolsCSS Border-Radius Generator
Adjust four corner radii and copy the CSS.
Developer ToolsCSS Box-Shadow Generator
Build and preview a CSS box-shadow declaration.
Developer ToolsCSS Clamp Calculator
Generate a fluid CSS clamp value between two viewport sizes.
Color ToolsCSS Gradient Generator
Create a two-color linear gradient and copy its CSS.
Developer ToolsCSS Grid Generator
Preview a column layout and generate copy-ready CSS Grid code.
Developer ToolsCSV and JSON Converter
Convert tabular CSV data to JSON and JSON arrays back to CSV.
Developer ToolsCSV Viewer and Editor
View and edit CSV data as a browser-based table.
ConvertersCurrency Converter
Convert currencies using dated ECB euro reference rates.
ConvertersData Storage Converter
Convert decimal and binary data storage units.
CalculatorsDate Difference Calculator
Calculate calendar years, months, days, total days, weeks, and weekdays between two dates.
GamesDice Roller
Roll multiple dice with configurable sides and a numeric modifier.
CalculatorsDiscount Calculator
Calculate savings, discounted price, and optional tax.
Text ToolsDuplicate Line Remover
Remove repeated lines from lists while preserving their original order.
CalculatorsElectricity Cost Calculator
Estimate appliance energy use and electricity cost.
Text ToolsEmail and URL Extractor
Extract unique email addresses and web links from text.
Image ToolsFavicon Generator
Generate common square favicon and app-icon PNG sizes from one image.
CalculatorsFraction Calculator
Add, subtract, multiply, or divide fractions and simplify the result.
ConvertersFuel Economy Converter
Convert US MPG, Imperial MPG, L/100 km, and km/L.
CalculatorsGreatest Common Divisor and LCM Calculator
Find the greatest common divisor and least common multiple of several integers.
Music ToolsGuitar and Piano Tuner
Estimate musical pitch from your microphone for tuning instruments.
Developer ToolsHash Generator
Generate SHA-1, SHA-256, SHA-384, or SHA-512 hashes from text.
Developer ToolsHTML Entity Encoder and Decoder
Encode HTML-sensitive characters or decode HTML entities.
Developer ToolsHTML Table Generator
Edit a browser table and generate its semantic HTML markup.
Image ToolsImage Compressor
Reduce image dimensions and quality to create a smaller download.
Image ToolsImage Format Converter
Convert images to PNG, JPEG, or WebP in your browser.
Image ToolsImage Metadata Remover
Remove common embedded image metadata by creating a clean re-encoded copy.
Image ToolsImage Resizer
Resize an image to custom pixel dimensions in your browser.
File ToolsImages to PDF Converter
Combine PNG and JPEG images into one downloadable PDF locally.
Learning ToolsInteractive Periodic Table
Explore all 118 elements by atomic number, symbol, category, period, and group.
Network ToolsIP Address Converter
Convert IPv4 and IPv6 addresses between normalized, integer, hexadecimal, and binary formats.
Network ToolsIP and Domain Lookup
Inspect approximate IP network details or public DNS records for a domain.
Network ToolsIPv4 Subnet Calculator
Calculate network, broadcast, mask, host range, and address counts from CIDR notation.
Developer ToolsJSON Formatter and Validator
Validate, format, or minify JSON directly in your browser.
Developer ToolsJWT Decoder
Decode JSON Web Token headers and payloads without uploading the token.
Learning ToolsKeyboard Key-Code Inspector
Inspect key, code, location, modifier, and repeat data from keyboard events.
Learning ToolsLarge Number Names
Compare short-scale and long-scale names such as billion, milliard, and trillion.
Electronics ToolsLED Resistor Calculator
Calculate a safe series resistor and power rating for LEDs.
Text ToolsList Randomizer
Shuffle a list securely or pick one random item.
CalculatorsLoan Payment Calculator
Estimate monthly loan payments, total interest, and payoff time.
Text ToolsLorem Ipsum Generator
Generate placeholder paragraphs for layouts and prototypes.
Developer ToolsMarkdown Editor and Preview
Write Markdown and see a safe live HTML preview.
CalculatorsMatrix Calculator
Add, subtract, multiply, transpose, and invert matrices with configurable dimensions.
Marketing ToolsMeta-Description Preview
Preview a page title and meta description in a search-style result.
Text ToolsMorse Code Translator
Translate text to International Morse code and back.
Text ToolsNATO Phonetic Alphabet Converter
Spell text with the NATO phonetic alphabet or decode phonetic words.
Developer ToolsNumber Base Converter
Convert whole numbers between bases 2 and 36.
Electronics ToolsOhm’s Law Calculator
Calculate voltage, current, resistance, and power from any two values.
Network ToolsPage Indexability Checker
Review public technical signals that can affect crawling and indexing.
Developer ToolsPassword Generator
Generate strong random passwords with configurable character sets.
File ToolsPDF Merger and Page Extractor
Merge PDF files or extract selected pages locally in your browser.
File ToolsPDF to Images Converter
Render PDF pages as downloadable PNG or JPEG images locally.
CalculatorsPercentage Calculator
Calculate a percentage of any number instantly with a simple browser-based calculator.
Image ToolsPhoto Editor and Effects
Adjust brightness, contrast, saturation, blur, rotation, and effects locally.
CalculatorsPrime Factorization Calculator
Break a whole number into prime factors and count its divisors.
CalculatorsPrint Size and DPI Calculator
Estimate print dimensions from image pixels and target DPI.
Marketing ToolsQR-Code Generator
Create a downloadable QR code from text or a URL.
Developer ToolsQuery String Parser and Builder
Inspect, edit, and rebuild URL query parameters.
CalculatorsRandom Number Generator
Generate configurable random integers or decimal numbers.
CalculatorsRatio Calculator
Simplify ratios and calculate equivalent proportional values.
Text ToolsReading Time Calculator
Estimate reading and speaking time from any text and chosen reading speed.
Developer ToolsRegular Expression Tester
Test JavaScript regular expressions and inspect every match.
Electronics ToolsResistor Color-Code Calculator
Decode four-band and five-band resistor color markings.
Marketing ToolsRobots.txt Generator
Create a simple robots.txt file with allow, disallow, and sitemap rules.
ConvertersRoman Numeral Converter
Convert standard Roman numerals and whole numbers from 1 to 3,999.
CalculatorsRunning Pace Calculator
Calculate pace per kilometer, pace per mile, and average speed.
CalculatorsSales Tax Calculator
Add sales tax to a price or extract tax from an inclusive price.
ConvertersScientific Notation Converter
Convert numbers between decimal, scientific, and engineering notation.
CalculatorsScreen PPI Calculator
Calculate display pixel density, pixel pitch, and physical dimensions.
ConvertersShoe Size Converter
Estimate EU, UK, and US adult shoe sizes from foot length or another size.
CalculatorsStatistics Calculator
Calculate count, sum, mean, median, mode, range, and standard deviation.
Time ToolsStopwatch and Lap Timer
Measure elapsed time and record individual lap times.
GamesSudoku
Generate and play accessible Sudoku puzzles at three difficulty levels.
CalculatorsTemperature Converter
Convert temperatures between Celsius, Fahrenheit, and Kelvin.
Text ToolsText and Binary Converter
Convert Unicode text to UTF-8 binary bytes and back.
Developer ToolsText Difference Checker
Compare two texts and highlight changed, added, and removed lines.
Text ToolsText Sorter
Sort lines alphabetically or naturally in ascending or descending order.
Electronics ToolsThree-Oscillator Sound Generator
Combine three oscillators with fine tuning and LFO pitch or volume modulation.
ConvertersTime-Zone Converter
Convert a date and time between world time zones with daylight-saving rules.
CalculatorsTip Calculator
Calculate a tip, total bill, and per-person amount.
Learning ToolsTyping Tutor
Practice typing and measure speed, accuracy, elapsed time, and progress.
Developer ToolsUnicode Character Inspector
Inspect characters, code points, UTF-16 units, and HTML entities.
CalculatorsUnit Converter
Convert common length, weight, and volume units with one flexible calculator.
Developer ToolsUnix Timestamp Converter
Convert Unix timestamps to readable dates and dates back to timestamps.
Developer ToolsURL Encoder and Decoder
Encode text for URL components or decode percent-encoded values.
Text ToolsURL Slug Generator
Turn titles and phrases into clean URL-friendly slugs.
Marketing ToolsUTM Link Builder
Build campaign URLs with properly encoded UTM tracking parameters.
Developer ToolsUUID Generator
Generate one or many random version 4 UUIDs.
Network ToolsWhat Is My IP?
View your public IP address and approximate network information.
Text ToolsWhitespace Cleaner
Clean repeated spaces, tabs, line edges, and excessive blank lines.
Text ToolsWord Counter
Count words, characters, sentences, and estimated reading time instantly in your browser.
Text ToolsWord Frequency Analyzer
Count repeated words and measure their share of a text.
Time ToolsWorld Time Meeting Planner
Compare one meeting time across four world time zones.
Developer ToolsXML Formatter and Validator
Check well-formed XML, format it, or create a minified copy.
Games2048 Puzzle
Merge matching number tiles and try to reach 2048.
GamesBreakout Game
Bounce the ball and break the blocks.
GamesFlag Explorer
Show a large flag, then reveal the country, continent, and capital.
GamesGeography Quiz
Answer quick country, capital, and continent questions.
GamesLights Out Puzzle
Turn off every light in the grid.
GamesMastermind Game
Crack the hidden color code.
GamesMemory Matching Game
Flip cards and find every matching pair.
GamesMinesweeper Game
Reveal safe squares and avoid the mines.
GamesNurikabe Puzzle
Shade cells around numbered islands.
GamesPower Grid Puzzle
Rotate the wires to light every bulb from the power source.
GamesReaction Time Game
Measure how quickly you can react when the target changes color.
GamesSimon Game
Repeat the flashing color sequence.
GamesSliding Puzzle
Arrange numbered tiles in order by sliding them into the empty space.
GamesSnake Game
Steer the snake, eat gems, and avoid the walls and your own tail.
GamesWord Search Game
Find hidden words in a letter grid.
ReferencesBattery Runtime Estimation Guide
Estimate runtime from watt-hours, load, efficiency, discharge limits, and battery chemistry.
ReferencesChemical Element Comparison Guide
Compare element families, states, conductivity, reactivity, and common uses.
ReferencesCooking Conversions and Substitutions
Common kitchen conversions, ingredient notes, and practical substitutions.
ReferencesCountry Codes, Currencies, and Time Zones
Compare codes, calling prefixes, currencies, and time zones for all 250 ISO-listed countries and territories.
ReferencesCSS and Browser Compatibility Checklist
A practical checklist for resilient layouts across modern browsers and devices.
ReferencesDNS Record Types Reference
Understand A, AAAA, CNAME, MX, TXT, CAA, NS, SOA, SRV, and PTR records.
ReferencesElectrical Wire Size Reference
Compare AWG wire diameters, areas, copper resistance, and illustrative current guidance.
ReferencesFile Signatures and Magic Numbers
Identify common file formats from their opening hexadecimal bytes.
ReferencesHTTP Status Codes and Security Headers
Reference common HTTP responses and the purpose of important browser security headers.
ReferencesLarge Number Scales Around the World
Understand billion, milliard, trillion, and the difference between short and long scales.
ReferencesPaper and Envelope Sizes
Compare ISO A-series paper, common North American sheets, and envelope dimensions.
ReferencesPhotography Exposure and Depth of Field
Understand aperture, shutter speed, ISO, focal length, focus distance, and depth of field.
ReferencesSolar Panel Output Estimation Guide
Estimate daily and annual solar generation from panel rating, sun hours, and system losses.
ReferencesUnicode Latin Characters, Symbols, and Emoji Reference
Browse Latin-script letters and combining marks used across many languages, plus punctuation, symbols, and emoji.
ReferencesWorld Currencies and Symbols
Reference currencies and symbols for all 250 ISO-listed countries and territories.
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