Tools

Use public tools other people built, and star the ones worth keeping.

Gym Membership Refund Calculator (Korea)

Works out the refund for cancelling a Korean gym membership under the Fair Trade Commission's dispute-resolution standard, and drafts a reference letter.

Academy Tuition Refund Calculator (Korea)

Refund for leaving a Korean private academy under the Enforcement Decree of the Academy Act, with a reference letter.

Postpartum Care Center Refund Calculator (Korea)

Refund for cancelling a Korean postpartum care center contract, before or after entry, with a reference letter.

Study Room Refund Calculator (Korea)

Works out the refund when you quit a Korean registered study room (dokseosil) early or the operator closes, under the Hagwon Act enforcement decree Annex 4.

Travel Cancellation Fee Calculator (Korea)

Cancellation fee for a Korean package or domestic tour under the standard terms, with a reference letter.

Wedding Hall Cancellation Calculator (Korea)

Penalty for cancelling a Korean wedding hall contract under the standard terms, with a reference letter.

Korean Hotel / Pension Booking Cancellation Refund Calculator

Works out the refund for cancelling a Korean hotel, pension or campsite booking under the Fair Trade Commission's dispute-resolution standard (lodging).

Show Ticket Cancellation Refund Calculator (Korea)

Works out the refund for cancelling a Korean concert, musical or play ticket under the Fair Trade Commission's dispute-resolution standard.

Golf Course Booking Cancellation Penalty Calculator (Korea)

Works out the penalty and deposit refund for cancelling a Korean golf course booking under the Fair Trade Commission's dispute-resolution standard and the standard golf course terms.

Water Purifier Rental Cancellation Fee Calculator (Korea)

Works out the early-termination fee for a Korean rental contract (water purifier etc.) under the Fair Trade Commission's dispute-resolution standard.

Moving Contract Cancellation Penalty Calculator (Korea)

Works out the penalty or compensation when a Korean moving contract is cancelled before the move date, under the Fair Trade Commission's dispute-resolution standard.

Korean Real Estate Brokerage Fee Calculator (Cap and Overcharge)

Works out the legal cap on a Korean real estate agent's commission for housing, officetels and other property, and how much of an amount already paid exceeds it.

Lease Renewal Notice Period and 5% Cap Calculator (Korea)

Works out the window for renewal notices on a Korean residential or commercial lease and the 5% rent increase cap. Korean only.

Rental Car Cancellation Refund Calculator (Korea)

Works out the refund for cancelling a Korean rental-car booking or ending a rental early, under the Fair Trade Commission's dispute-resolution standard and the standard rental terms.

Insurance Cooling-off Deadline Calculator (Korea)

Finds the deadline to withdraw a Korean insurance application (the earlier of 15 days after receiving the policy and 30 days after applying) and the 3-month cancellation date.

Funeral Service (Sangjo) Cancellation Refund Calculator (Korea)

Works out the minimum refund when you cancel a Korean prepaid funeral-service (sangjo) installment contract early, under the Fair Trade Commission's notice.

Late Payment Interest Calculator (Korea)

Calculates late payment interest on an unpaid sum by date: 5% civil, 6% commercial or an agreed rate, switching to the 12% litigation rate after the complaint is served. Korean only.

Refund Policy Notice Maker (Korea)

Generates a refund policy notice for Korean gyms, academies, study rooms and postpartum care centers based on the consumer dispute resolution standards. Korean only.

Loan Repayment Schedule Calculator (Korea)

Builds a payment schedule for equal-payment, equal-principal and bullet loans with grace periods and prepayment fees. Korean only.

Freelancer 3.3% Withholding and Income Tax Estimator (Korea)

Calculates the 3.3% withholding on freelance payments in Korea and estimates the annual income tax settlement. Korean only.

Overtime, Holiday Pay and Severance Calculator (Korea)

Calculates Korean overtime, night and holiday premiums, weekly holiday allowance and severance pay. Korean only.

Payslip and Social Insurance Calculator (Korea, 2026 rates)

Calculates Korean social insurance deductions, net pay and employer contributions for 2026. Korean only.

Gift Certificate & Gifticon Refund Calculator (Korea)

Works out the refund for a Korean gift certificate or mobile gifticon within 7 days of purchase, for an unused balance, or after expiry, under the Fair Trade Commission's dispute-resolution standard.

Character & Byte Counter (Korean NEIS, Resumes)

Paste text to get character counts with and without spaces, plus byte counts under three rules side by side: NEIS (Korean school records), UTF-8 and EUC-KR (job-site style). Enter a limit such as 1500 bytes or 500 characters to see what is left or where you went over. The limits are editable.

Cron Expression Parser: Next Run Times in KST and UTC

Explains a 5-field cron expression and lists the next 10 run times in Korea Standard Time (KST) and UTC, with the equivalent expression for a server running on UTC.

JWT Decoder (expiry in KST)

Paste a JWT to see its header and payload as colored JSON, with exp, iat and nbf converted to UTC and Korea Standard Time plus the time left before expiry. Can also verify HS256, HS384 and HS512 signatures.

Subnet & CIDR Calculator

Enter an IPv4 address with a prefix length (/24) or subnet mask to get the network and broadcast addresses, usable IP range and host count, with binary working and a subnet split table.

Unix Timestamp Converter (KST)

Convert a Unix timestamp (epoch time) to Korea Standard Time (KST) and UTC, or a KST date back to seconds and milliseconds. It tells seconds from milliseconds by digit count and shows the current timestamp live.

Color Contrast Checker (WCAG and KWCAG)

Enter a text and a background color to get the WCAG 2.2 contrast ratio and AA/AAA pass or fail for normal text, large text and UI components. Explains the 4.5:1 rule used by Korea's KWCAG 2.2 and suggests the nearest passing color when a pair fails.

px rem pt mm Unit Converter

Convert px, rem, em, pt, pc, in, cm, mm and Q in one go. Set the root font size and viewport width for rem and vw, and work out print pixel dimensions for A4, A5 and B5 at 72 to 600 dpi.