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Side Note — The History of the Capo, a Shortcut for Transposition
The capo was invented to solve a problem that fretted instruments like the lute and guitar have struggled with for centuries: transposing is far more awkward than on a piano, where you can shift to any key just by moving your fingers to different keys. On a guitar, changing key often means swapping...
Read more at Guitar Capo Chart & Position Calculator →Crypto
Generator
Memorable Passphrase Generator (Diceware-style)
TOTP (One-Time Password) Generator
Hash
MD5 Hash Converter — Free Online MD5 Calculator
SHA-256 Hash Generator — Free Online Tool
Argon2 Hash Calculator | Argon2id, Argon2i & Argon2d
Argon2 Hash Verification | Compare a Password Against an Encoded Hash
Compute All Hashes at Once — MD5, SHA-1, SHA-256, SHA-512, SHA-3, BCrypt, Argon2id
File Hash Calculator — Verify Downloads with MD5, SHA-1, SHA-256, SHA-512
Bcrypt Verification
BCrypt Hash Checker | Verify Password Matches Hash Instantly
Classical Ciphers
Caesar Cipher & ROT13 Generator
Developer Tools
Generator
UUID Generator — Bulk v4 Generation, No-Hyphens & Uppercase Formats
Formatter
JSON Lines (JSONL) ⇔ JSON Array Converter
JSON to TypeScript Type Converter
Go Struct to JSON Sample Generator
CSV
CSV to SQL Converter (INSERT Statement Generator)
CSV to Markdown Table Converter
Markdown Table to CSV Converter
CSV ⇔ JSON Lines (JSONL) Converter
Encoding
Base64 Encode / Decode — Free, No Sign-up
ASCII Code Table (Free) — Character to Code Converter
Line break at a specified length
Mojibake Converter & Fixer — Character Encoding Repair Tool
SNS Character Counter (Twitter/X-style Count)
Extension ↔ MIME Type Converter
Unicode / Character Code Cross-Reference
File to Base64 Converter (with data URI support, both directions)
Server Config
Testing & Demo
Test Card Numbers for Stripe, PayPal, Braintree & Square (2026 List)
Credit Card Number Validator | Luhn Algorithm & Brand Detection
Sample CSV (Dummy Data) Generator
Text Processing
List Compare Tool (Common & Unique Lines)
Scheduler
Cron Expression Parser & Next Run Calculator
Cron Expression to systemd Timer Converter
systemd Timer to Cron Expression Converter
SEO Validators
JSON-LD Structured Data Validator
Web App Manifest (manifest.json) Validator
Robots Meta Tag / X-Robots-Tag Validator
JWT
JWT Signature Verifier (RS256/ES256, Public Key Verification)
Binary & Numbers
Data Size Converter (Bytes, KB, MB, GB, TB)
Number Base Converter (Binary, Octal, Decimal, Hexadecimal)
Bitwise Operation Simulator (AND, OR, XOR, NOT, Shift)
Byte Length Counter by Encoding
Binary Hex Editor | View and Edit Files in Hexadecimal
Two's Complement Calculator (Signed Integer Binary Converter)
Text
Text Analysis
Word Counter (Characters, Words and Reading Time)
Japanese Word Counter | Accurate Even Without Spaces
Case Converter — kebab-case, camelCase, snake_case (Free)
Number ↔ Kanji Numeral Converter
Jōyō Kanji List — Elementary School Readings & Stroke Counts (Grades 1–2)
Fun
Emoji Search & List — All Unicode Emoji to Copy and Paste
"Ojisan" Text Style Generator (Japanese "Uncle-Speak")
"Gyaru-go" Text Style Generator (Japanese Gal Slang)
Okinawan Dialect ("Uchinaguchi") Generator
Fancy Text Generator (Unicode Stylish Fonts)
Morse Code Encoder (Text to Morse Code)
Morse Code Decoder (Morse Code to Text)
Flag Semaphore Encoder (Text to Signal Diagrams)
Flag Semaphore Decoder (Positions to Text)
Japanese Business Honorifics Chart ("Kisha" / 貴社) by Organization Type
Phonetic Alphabet Converter (NATO Alphabet) | Alpha, Bravo, Charlie
Generators
Math
Basic Calculations
Calculator (Free, No Sign-up) — Type Full Formulas with Parentheses
Discount Calculator — % Off, Markdown & Half-Price in One Click
Compound Interest Calculator with Monthly Deposits
Million/Billion/Trillion Converter — 万/億/兆 (Free)
Big Number Calculator — Exact Arithmetic with Unlimited Digits (BigInt)
Scientific Calculator (sin, cos, tan, log, power, factorial)
Fraction Calculator (Add, Subtract, Multiply, Divide, Simplify)
Factorial Calculator (n!, Permutations nPr, Combinations nCr)
Statistics Calculator (Mean, Median, Variance, Standard Deviation, Quartiles)
GPA Calculator (Grade Point Average)
Scale Calculator (Convert Between Actual Size and Drawing Length)
Function Graphs
Linear Function Grapher y = ax + b (Free Online Tool)
Quadratic Function Grapher & Calculator — Vertex and Roots
Cubic Function Grapher & Calculator — Inflection and Extrema
Exponential Function Graph (y = a·bˣ + c)
Logarithm Graph Maker — Free Online (y = a·log_b(x) + c)
Ellipse Graph (x²/a² + y²/b² = 1)
Hyperbola Graph (x²/a² − y²/b² = 1)
Chart Maker
Free Pie Chart Maker — Online Tool
Sequences
Arithmetic Sequence Calculator (aₙ = a₁ + (n−1)d)
Geometric Sequence Calculator (aₙ = a₁·rⁿ⁻¹)
Fibonacci Sequence Calculator — Instant Nth Term & Golden Ratio Chart
Figurate Numbers Calculator (Triangular, Square, Pentagonal, Hexagonal)
Number Theory
Prime Number Checker – Up to 1,000 Digits, Free
Sieve of Eratosthenes Generator (Free) – List Primes & Find the Nth Prime
Prime Factorization Calculator — Free Online Tool (up to 1,000,000)
Modular Arithmetic Calculator (Mod Calculator)
Chinese Remainder Theorem (CRT) Calculator — Solve Simultaneous Congruences
Euler's Totient Function (φ) Calculator
Geometry
Triangle Calculator (Sides, Angles, Area)
Bearing & Distance Calculator (Latitude/Longitude)
Vector Calculator (Dot Product, Cross Product, Magnitude, Unit Vector, Angle)
Slope Calculator (Degrees, Percent Grade, Ratio)
Size & Unit Converters
Unit Converter (Length, Weight, Temperature)
Area Unit Converter (m², tsubo, tatami mats, acres, and more)
Shoe Size Converter (Japan, US, UK, EU)
Ring Size Converter (Japan, US, UK, EU)
Clothing Size Converter (Women's & Men's / Japan, US, UK, EU)
Date/Time
Clocks & Timers
Timezone Converter | Instantly Calculate the Time Difference (Free)
World Clock — Free Interactive Map, Any Date & Time Zone (DST-Aware)
Calendar
Japan Holiday Calendar — Is This Date a Holiday? Plus Streak Ranking
Holiday Checker (Is This Day a Holiday?)
Rokuyou Calendar (Auspicious & Inauspicious Days at a Glance)
CE / Japanese Era Quick-Reference Chart — Era Changeover Dates & Age by Birth Year
Japanese Era Names (Gengō) — Full List, Taika to Reiwa
Free Japanese Name Numerology (Seimei Handan)｜Five Grids by Kanji Stroke Count
Edo-Era Japanese Time Converter — Zodiac Hours & Bells
Japanese Seasonal Letter Greetings by Month
Age & Life
Japan Age Calculator with Japanese Era (Wareki)
Yakudoshi & Happosagari Checker
Japan School Age Calculator (Elementary, Middle, High School, Retirement by Birth Year)
Japanese School Timeline Calculator (Enrollment & Graduation Years)
Japanese Longevity Milestones Calculator
Japanese Buddhist Memorial Service Calculator (Isshuki, Sankaiki, Nanakaiki)
Mochu Hagaki Checker — Japanese Mourning Postcard Eligibility & Timing
Koden-Gaeshi Calculator (Funeral Return Gift Amount)
Buddhist Memorial Service Offering (Ofuse) Calculator
Condolence Money (Koden) Amount Calculator — Giving Side
Wedding Gift Money (Goshugi) Amount Calculator — Giving Side
Childbirth Gift Money Amount Calculator — Giving Side
Calculators
Date Calculator (Add or Subtract Days)
Time Duration Calculator (Add/Subtract Hours, Minutes, Seconds)
Design
Color
RGB ⇄ Hex Color Code Converter — Free, No Sign-Up
Color Model Converter (RGB, HSL, HSV, CMYK)
Contrast Ratio Checker (WCAG Compliance Check)
Color Palette Reference — Copy Standard Web & Material Design Colors
Extract Colors from an Image (Dominant Color Extractor)
RGBA to RGB Converter (Flatten onto a Background)
Icon
Favicon Generator | Multi-Size ICO and PNG in One Click
CSS
CSS position Property Generator
PX to REM Converter (& REM to PX)
Image
Aspect Ratio Calculator & Converter (Simplify & Resize)
Placeholder Image Generator (Sample Image Maker)
Image Compressor (Free, No Upload — Reduce Image File Size)
Image Format Converter (PNG/JPG/WebP)
HEIC Converter — HEIC to JPG, PNG and WebP (Free, Batch)
AVIF to JPG Converter (also PNG, WebP) — Free, Batch
Combine Images Online — Free Image Joiner
Image Resizer (Resize by Width & Height)
Make Image Transparent (Remove Solid-Color Background)
Documents & Print
Paper Size Chart (A/B Series, mm to px Converter)
Network
URL & API
curl Exit Code List: Look Up Any Code (1-99), Meaning & Fix
IP & Subnet
Subnet Calculator & Quick-Reference Table — Free, /1–/32 CIDR
CIDR / Subnet Mask Reference Table
What Is My IP Address? Free IP Checker
IP Address / Domain Blacklist (DNSBL) Checker
IP Address Validator — Check IPv4/IPv6 Format & Detect Private Ranges (Free)
IPv6 CIDR Reference Table — Address Counts by Prefix Length (Free)
Subnet Overlap Checker — Detect Whether Two CIDR Blocks Overlap (Free)
Domain
Punycode Converter (Internationalized Domain Names)
Domain Name Validator (RFC Compliance Check)
SSL Certificate Checker (Expiry & Issuer Lookup)
TLS Protocol Version Diagnostic Tool
Reference
Free Internet Speed (bps) Converter | Kbps, Mbps, Gbps & Bandwidth Guide
DNS Record Type Reference Guide
DNS Propagation Checker (Free) - Check DNS Records Worldwide
Money
Salary & Tax
Japan Net Salary Calculator: Annual Income to Take-Home Pay
German Salary Calculator (Brutto Netto Rechner) – Gross to Net Pay
French Salary Calculator (Salaire Brut en Net)
Self-Employed Tax Calculator (UK) — Income Tax & Class 4 NI
UK Dividend Tax Calculator — Director's Salary & Dividends
Spain Net Salary Calculator (Salario Bruto a Neto)
Italy Net Salary Calculator (Calcolo Stipendio Netto)
Freelancer Take-Home Pay Simulator (Japan) — Income Bracket Quick Reference
Gross-Up Calculator — Reverse-Calculate Salary from Take-Home Pay
Japan Bonus Take-Home Pay Calculator (Free) | Social Insurance & Withholding Tax
Overtime Pay Calculator - Overtime, Late-Night & Holiday Wage Premiums (Japan)
Paid Leave Days Calculator - Entitlement & Balance from Your Hire Date (Japan)
Furusato Nozei Limit Calculator
Salary to Hourly Wage Converter | Annual, Monthly & Daily Pay
Japan Income Percentile & Deviation Score Calculator
Maternity Allowance Calculator (Japan Shussan Teatekin)
Sickness and Injury Allowance Calculator (Japan Shobyo Teatekin)
High-Cost Medical Expense Benefit Calculator (Japan Kogaku Ryoyohi)
Medical Expense Deduction Calculator (Japan Iryohi Kojo)
Self-Medication Tax System Calculator (Japan)
Specific Expense Deduction Calculator
Life Insurance Premium Deduction Calculator
Earthquake Insurance Premium Deduction Calculator
Japan Childcare Leave Benefit Calculator
Severance Pay Take-Home Calculator (Retirement Income Deduction & Separate Taxation)
Japan "Income Wall" Calculator (¥1.03M/1.06M/1.30M/1.50M Walls)
Wealth Building & Investing
Mortgage Refinance Calculator — Break-Even & Total Savings
HELOC Repayment Calculator — Draw Period vs. Repayment Period
Cash-Out Refinance Calculator | Compare Tapping Equity vs. a Separate Loan
Home Equity Loan Calculator | Monthly Payment, Total Interest & Combined Loan-to-Value (CLTV)
HELOC vs. Home Equity Loan Calculator
DTI Calculator (Debt-to-Income Ratio)
Mortgage Repayment Method Comparison (Equal Installment vs Equal Principal)
Debt Payoff Calculator (Snowball vs. Avalanche)
Rent vs Buy Comparison Simulator
Savings & Investment Calculator
New NISA Simulator (Tsumitate & Growth Investment Quotas)
Investment Return Calculator (Free Compound Interest Simulator)
Learn Technical Indicators (MACD, RSI, Bollinger Bands)
Real Estate Investment Calculator
Japanese Inheritance Tax Simulator | Estimate Tax From Estate Value and Heirs
Lifetime Gift Planner | Simulate Annual Gifting vs. Inheritance Tax (Japan)
Lump-Sum Gift Settlement Simulator | Estimate Combined Gift & Inheritance Tax (Japan)
Life Insurance Inheritance Tax Exemption Calculator | Estimate the Tax Difference
Life Insurance Needs Calculator | Estimate How Much Coverage You Need
Term Life vs Income Protection Insurance Comparison | Compare Premiums for the Same Coverage
Spousal Inheritance Tax Reduction Calculator | First & Second Inheritance Combined
Small-Scale Residential Land Exception Calculator | Reduce Land Value up to 80%
Inheritance Tax Minor & Disability Deduction Simulator | Estimate Deductions and Tax Owed
Consecutive Inheritance Tax Credit Simulator | Reduce Tax When Inheritance Occurs Within 10 Years
Foreign Tax Credit Simulator for Inheritance Tax | Ease Double Taxation on Overseas Assets
Japanese Inheritance Tax 20% Surcharge Simulator | How Much More Do Non-Spouse/Child Heirs Pay?
Spousal Residence Right Valuation Simulator | How Much Is the Inheritance Tax Value?
Base Estate Value Calculator for Forced Heirship | Factor In Lifetime Gifts for an Accurate Figure
Forced Heirship Claim Simulator | Did a Will or Gift Leave You Short of Your Reserved Portion?
Forced Heirship Apportionment Calculator | How Multiple Recipients Share the Burden
Special Benefit Advancement Calculator | Simulate Each Heir's Concrete Share
Contribution Share (Kiyo-bun) Calculator | Simulate Your Concrete Inheritance Share
Excess Advancement Reapportionment Calculator | Reallocate an Inheritance Fairly
Living Costs
Electricity Cost Calculator | Estimate Monthly Bill by Appliance
Car Maintenance Cost Calculator | Monthly & Annual Running Costs
Vehicle Tax Calculator (Japan)
Vehicle Tax Proration Calculator (Japan)
Environmental Performance Tax Calculator (Japan)
Compulsory Automobile Liability Insurance (CALI / Jibaiseki) Calculator
Vehicle Weight Tax Calculator (Japan)
Japan Vehicle Recycling Fee Estimator
Japan Vehicle Inspection (Shaken) Total Cost Calculator
EV vs Gasoline Car Lifetime Cost Comparison
Kei Car vs Regular Car Running Cost Comparison
Japanese Car Insurance Grade Premium Calculator
Japanese Car Insurance Claim vs Self-Pay Break-Even Simulator
Second-Car Discount Eligibility Checker & Grade Simulator
Gold License & Driver Age Condition Premium Impact Comparison
Driver Scope Rider (Named Insured Only / Named Insured & Spouse Only) Premium Impact Comparison
Deductible (Self-Pay Amount) Change Premium Impact Comparison
Telematics Insurance Enrollment Premium Impact Comparison
Sales Channel (Agent vs. Direct) Insurance Premium Impact Comparison
Paperless Policy Discount Insurance Premium Impact Comparison
Usage Purpose (Daily/Commute/Business) Insurance Premium Impact Comparison
Commute Cost Comparison (Car vs Public Transit)
Everyday Calculators
Percentage Calculator | 4 Modes: Discount, Increase, Ratio & More
VAT Calculator | Add or Remove VAT and Compare Rates by Country
VAT Number Validator - Offline Format & Check Digit Verification
Lottery & Gambling Odds
Lottery Win Simulator | Visualize Expected Value & Payout Ratio with Monte Carlo
Which Lottery Is Easiest to Win? Loto 6 vs Loto 7 vs Bingo 5
Lottery Winnings Gift Tax Simulator | Tax on Sharing Prize Money With Family
Business
SaaS Metrics
Net Revenue Retention (NRR) Calculator
Gross Revenue Retention (GRR) Calculator
Cohort Retention Table & Chart Generator
SaaS ARR per Employee Calculator
ARPA (Average Revenue Per Account) Calculator
Sales Metrics
ACV (Annual Contract Value) Calculator
Weighted Pipeline Value Calculator — Forecast Revenue from Deal Size & Win Probability
Creator Economy
Ad Revenue & YouTube Earnings Calculator
SNS Engagement Rate Calculator
Influencer Sponsored Post Rate Calculator
SNS Follower Growth Rate & Target Date Calculator
Business Metrics
Marketing Metrics Calculator — CTR, CPC, ROAS & LTV
Progress Rate Calculator | Weighted Average of Multiple Tasks
NPS (Net Promoter Score) Calculator | Free Customer Loyalty Metric
eNPS (Employee Net Promoter Score) Calculator | Free Employee Engagement Metric
Turnover Rate Calculator | Free Voluntary vs. Involuntary Breakdown
Cost per Hire Calculator | Free Recruiting Cost Breakdown
Time to Hire Calculator | Free Recruitment Lead Time Calculation
Quality of Hire Score Calculator | Weighted Multi-Metric Free Calculation
Offer Acceptance Rate Calculator | Free Hiring Funnel Yield Tool
Hiring Funnel Conversion Rate Calculator | Free Recruiting Analysis
New Hire Retention Rate (Early Turnover Rate) Calculator | Free Post-Hire Retention Tool
Absenteeism Rate Calculator | Free HR Metric Tool
Paid Leave Utilization Rate Calculator | Free HR Metric Tool
Overtime Hours & Article 36 Agreement Limit Checker | Free 45h/Month & 360h/Year Alert
CSAT (Customer Satisfaction Score) Calculator | Free Survey Aggregator
Customer Effort Score (CES) Calculator | Quantify How Easy Support Was
Gross Margin Calculator (with Cost Ratio) | Free Profitability Tool
Operating Margin Calculator (Revenue, COGS & SG&A)
Ordinary Income Margin Calculator (Operating Profit & Non-Operating Income/Expenses)
Net Profit Margin Calculator (From Ordinary Income, Extraordinary Items & Taxes)
Break-Even Point Calculator (Fixed & Variable Costs)
Depreciation Calculator (Straight-Line & Declining Balance)
Small Asset Depreciation Checker (Japan Tax Rules)
Japan Corporate Tax Calculator (Estimate)
Japan Corporate Tax Interim Payment Calculator
Japanese Consumption Tax Interim Payment Calculator (Chukan Shinkoku)
Japan Invoice Registration Number Validator | T-Number Check Digit Verification
File Operations
Chemistry
Basics
Periodic Table of Elements — Search & Detailed Data for All 118 Elements
Ideal Gas Law Calculator (PV=nRT)
pH Calculator (Acid/Base Test)
Molarity & Dilution Calculator (C1V1=C2V2)
Radioactive Isotope Half-Life Calculator
Chemical Equation Balancer (Coefficient Calculator)
Partial Pressure Calculator (Dalton's Law)
Water Vapor Pressure Calculator (Antoine Equation)
Raoult's Law Calculator (Boiling Point Elevation & Freezing Point Depression)
Physics
Mechanics
Uniform Acceleration Calculator (Velocity & Displacement)
Work & Energy Calculator (Work, Kinetic Energy & Potential Energy)
Friction Force Calculator (Static, Kinetic & Inclined Plane)
Momentum & Collision Calculator (Elastic, Inelastic, Restitution Formula) - Free
Simple Harmonic Motion Calculator (Spring-Mass & Pendulum)
Uniform Circular Motion Calculator (Centripetal Force, Angular Velocity, Period)
Torque (Moment of Force) Calculator — τ = rFsin(θ)
Electricity
Ohm's Law Calculator (Voltage, Current, Resistance)
Resistor Color Code Calculator (Color to Value & Value to Color)
Series & Parallel Resistor Calculator (Total Resistance)
Ceramic Capacitor Code Converter (Code to Capacitance & Capacitance to Code)
Free LC Resonant Frequency Calculator | Inductor-Capacitor Circuit
Inductor (Coil) Color Code Calculator (Colors → Inductance & Inductance → Colors)
RC Circuit Time Constant Calculator (with Charge/Discharge Graph)
Music
Practice
Note Name to Frequency Converter (Concert Pitch Supported)
Chromatic Tuner (Free, Online)
Circle of Fifths — Click a Key to See Its Signature, Relative Key, and Chords
Guitar Capo Chart & Position Calculator
BPM to Delay Time (ms) Calculator
Chord Progression Generator ― Pick a Key and Play Popular Progressions
Chord Finder — Identify Chord Names from Notes (Piano Keyboard)
Media
Device Tests
ID Photo Maker with Your Webcam | Passport & Visa Sizes
Microphone Test (Free, Online)
Speaker & Headphone Test (Free, Online)
Dead Pixel Test (ドット抜けチェック) — Free Fullscreen Screen Check
Keyboard Tester | Check Every Key, Ghosting & N-Key Rollover (NKRO)
Reaction Time Test — Measure Your Reflexes in Milliseconds
Color Blind Test — Free Online Color Vision Check
Hearing Test Online — Check Your High-Frequency Hearing Range
Health
Checkups & Reference Values
Health Checkup Reference Guide
Calculators
BMR Calculator (Basal Metabolic Rate)
Macro Calculator (Protein, Fat, Carb Split)
Body Fat Calculator (Tape Measure Only, No Scale Needed)
Lean Body Mass (LBM) Calculator
Alcohol Elimination Time Calculator (Blood Alcohol Content Simulator)
One Rep Max Calculator (1RM Calculator)
Pace Calculator (Distance, Time & Pace Converter)
Pregnancy Due Date & Ovulation Calculator
Daily Life
Travel & Transport
Travel Time & Step Count Calculator
Fuel Cost Calculator | Distance, Efficiency & Price
Science & Nature
Layers of the Atmosphere (Interactive Diagram)
Pets
Dog Age Calculator (Dog & Cat Years to Human Years, by Breed Size)
Dog & Cat Body Condition Score Checker (BCS Rating & Ideal Weight Estimate)
Dog & Cat Daily Feeding Amount & Calorie Calculator (by Weight & Life Stage)