Free Online Tools
Free tools for everyday life and business — mortgage calculator, investment simulator, salary calculator, JSON formatter, password generator, and more. Everything runs in your browser. Your data is never sent externally.
Loans & Investment
Mortgage Calculator
Calculate monthly payments, total payments, and total interest for mortgages with equal payment or equal principal methods.
Investment Simulator
Simulate future asset value from monthly contributions and expected returns.
iDeCo / NISA Tax Saving Simulator
Simulate tax savings and investment returns from iDeCo and NISA contributions.
Car Loan Calculator
Calculate monthly payment, total payment, and total interest for car loans from interest rate and repayment period.
Loan Prepayment Simulator
Simulate interest savings and term reduction from mortgage prepayments. Compare term-shortening and payment-reduction methods.
Tax & Salary
Take-home Pay Calculator
Calculate take-home pay after social insurance and taxes from gross annual salary.
Pension Simulator
Estimate old-age basic pension and employee pension amounts from enrollment period and average salary.
Furusato Tax Deduction Simulator
Calculate your maximum Furusato tax deduction based on income and family composition. Supports freelancers and side income.
Inheritance Tax Simulator
Calculate estimated inheritance tax from total estate value and number of legal heirs. Shows basic deduction, taxable estate, and tax amount.
Income Tax Calculator
Calculate income tax and tax refund/payment from salary, side income, medical expense deductions, and more.
Retirement Bonus Tax Calculator
Calculate take-home amount after deducting retirement income deduction, income tax, and resident tax.
Health
BMI Calculator
Calculate BMI from height and weight and assess obesity level based on Japan Society for the Study of Obesity standards.
Body Fat Calculator
Estimate body fat percentage from height, weight, age, and gender using the BMI method.
Sleep Cycle Calculator
Suggests optimal wake-up or bedtimes based on 90-minute sleep cycles for refreshing mornings.
Developer Tools
Character Counter
Count characters, words, lines, and bytes in real-time. Supports full-width characters.
JSON Formatter & Minifier
Format, minify, and validate JSON data in your browser.
Base64 Encode/Decode
Instantly encode and decode Base64 text in your browser. Supports multi-byte characters.
Hash Generator (SHA-256, etc.)
Generate SHA-1/SHA-256/SHA-384/SHA-512 hash values in your browser. Data is never sent to a server.
URL Encode/Decode
Encode and decode URLs in real-time. Supports Japanese URL conversion.
Unix Timestamp Converter
Convert between Unix timestamps and dates. Auto-detects seconds vs. milliseconds.
Text Diff
Compare two texts and highlight added and removed lines. Useful for code review and document comparison.
Regex Tester
Test regex matching and replacement in real-time. Supports group capture inspection.
CSV / JSON Converter
Convert between CSV and JSON in your browser. Supports header row auto-detection.
Cron Expression Generator
Easily generate and edit cron expressions with a GUI. Includes natural language descriptions and execution previews.
QR Code Reader
Read QR codes from image files. Supports JPEG, PNG, GIF, and WebP.
Converters
Image Compressor
Compress and resize images in your browser. Nothing is uploaded to a server.
Color Code Converter
Convert between HEX, RGB, and HSL color codes. Includes an intuitive color picker.
Unit Converter
Convert between units of length, weight, temperature, area, volume, speed, and data.
PDF Merge / Split / Compress
Merge, split, and compress PDF files in your browser. Data is never sent to a server.
Image to PDF Converter
Combine multiple images into a PDF. Save as PDF using your browser's print function.
Image Resizer
Resize images by pixel, percentage, or social media presets. Supports aspect ratio lock. Data is never sent to a server.
Generators
QR Code Generator
Generate QR code-style pattern images from text or URLs. Downloadable as PNG.
Password Generator
Generate strong passwords using cryptographically secure random numbers.
Random Number Generator
Generate random numbers within a specified range and count. Supports no-duplicates and integer-only modes.
Calculators
Date Counter
Calculate days, weeks, business days, and more between two dates.
Age Calculator
Calculate your exact age, total days lived, days until next birthday, and zodiac sign from your date of birth.
Sales Tax Calculator
Calculate tax-inclusive from tax-exclusive prices, or vice versa. Supports standard 10% and reduced 8% rates.