About
About This Site
HandyTools (calc.codingmachine.co.kr) is a free online service designed to help anyone perform accurate financial calculations and everyday lookups with ease. Launched in March 2026, we currently offer over 34 calculators and information lookup tools, with new tools being added continuously. HandyTools provides financial calculators specialized for Korean tax law, including salary after-tax calculations, severance pay, loan interest comparisons, VAT calculations, and capital gains tax simulations. We also feature various practical lookup functions such as exchange rates, apartment transaction prices, gas station prices, financial product rate comparisons, and product price lookups. We also provide commonly used everyday tools including unit converters (length, weight, temperature, area, volume, speed, data size), percentage calculations, BMI calculations, and compound interest calculations — allowing you to handle various calculations and lookups all in one place.
Our Purpose
Our goal is to simplify complex financial calculations and everyday lookups so you can make smarter decisions. All tools are free to use without registration, and the data you enter is processed only in your browser — nothing is stored on our servers.
Key Features
We provide accurate calculations based on Korean tax law, multilingual support (Korean and English), mobile-optimized design, dark mode support, and a privacy-safe service that does not collect personal information.
Data Sources and Methodology
HandyTools utilizes official APIs and data from the Korean government and public institutions to provide accurate and reliable information. • Bank of Korea Economic Statistics System (ECOS): Real-time integration of key economic indicators including base interest rates, Consumer Price Index (CPI), and CD 91-day rates. Used for inflation-adjusted compound interest calculations and loan interest base rate references. • Korea Eximbank: Real-time exchange rate information including buying/selling rates and remittance rates. Updated every hour. • Financial Supervisory Service (FSS): Comparative rates for 5 types of financial products — deposits, savings, mortgages, jeonse loans, and credit loans. Updated every 24 hours. • Ministry of Land, Infrastructure and Transport: Integration with the apartment transaction price disclosure system and car-sharing information service. • Korea National Oil Corporation (OPINET): Gasoline, diesel, and LPG prices at gas stations nationwide, available by region and brand. • Financial Services Commission: Securities data including stock prices and dividend information. • Ministry of the Interior and Safety: Regional waste disposal information. • Korea Astronomy and Space Science Institute: 5 types of special day information including public holidays, memorial days, 24 solar terms, miscellaneous days, and national holidays. • Public Data Portal (data.go.kr): Various public data including online-collected product prices. Tax calculations apply the current tax rates and contribution rates based on 2026 Korean tax law, including the Income Tax Act, Local Tax Act, National Pension Act, National Health Insurance Act, and Employment Insurance Act. We strive to reflect legislative amendments as quickly as possible, though there may be some delay.
Technology and Security
HandyTools utilizes modern web technologies to provide a fast and secure service. • Built on Next.js 15 with server-side rendering (SSR) and static site generation (SSG) for fast page loading speeds. • All calculations are performed in the user's browser (client-side), so personal financial data is never transmitted to our servers. • HTTPS encrypted communication ensures all data transfers are secure. • Responsive design provides an optimized experience on all devices — PC, tablet, and mobile. • Dark mode support to reduce eye strain. • Bilingual support (Korean and English) for convenient use by international users.
Update History
• March 2026: Service launch. Initial calculators including salary after-tax, severance pay, compound interest, salary-to-hourly, VAT, exchange rate, percentage, BMI, and unit converters (length, weight, temperature, area, volume, speed, data size). • March 2026: Added housing subscription points, loan interest (3 repayment methods with ECOS integration), capital gains tax (with apt transaction price lookup), lease rate calculator, and year-end tax settlement. • March 2026: Added financial product rate comparison (FSS API), product price lookup (data.go.kr), gas station prices (OPINET), electricity bill (progressive rates), apartment transaction prices, stock capital gains tax, investment simulator, stock return, and dividend calculators. • March 2026: Added waste disposal info, nearby gas station map (Leaflet), holiday/memorial day calendar, car-sharing depot lookup, and world clock/stopwatch.
Operator Information
This website is a non-commercial information service operated by an individual.
Contact
If you have any questions, please contact us at 2000ko132@gmail.com.