AvailableDevelopers & AI

Calculation API

Call 24 calculators as JSON: 16 refund calculators plus late interest, loan schedules, overtime and severance pay, payslips, freelancer withholding and lease renewal. Each response carries a sentence and the numbers, so you can show it as is.

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Key features

Sentence + numbers

Each response has a readable answer, the calculated values (result) and the legal basis (basis).

24 calculators

Refunds for gyms, academies, travel, weddings, lodging and funeral plans, plus late interest, brokerage fees, loans, severance, payslips and lease renewal.

Usage at a glance

The x-quota-used response header shows this month's usage.

50,000 calls a month

Past the limit you get a 429. Contact us if you need more.

Public spec

Tool names and inputs are documented in an OpenAPI file.

AI-ready

A keyless MCP endpoint (tool.avenpa.com/mcp) is also open.

How it works

Request a key

Email us your business name.

Try a call

Paste the example below into a terminal and check the response.

Wire it in

Tool names and inputs are in openapi.json.

Using the API

Example request

curl -H "Authorization: Bearer YOUR_KEY" \
  "https://business.avenpa.com/api/v1/calc/calc_gym_refund?total_price=360000&start_date=2026-01-01&end_date=2026-12-31&cancel_date=2026-06-30"

Example response

{
  "answer": "Consumer-side cancellation: refund is 145,479 KRW … (Korean text)",
  "result": { "usedDays": 181, "used": 178521, "penalty": 36000, "refund": 145479, "payout": 145479 },
  "basis": "…"
}

You can also POST a JSON body. Pass the key in the Authorization header or as a key parameter.

Tool names (call with the calc_ prefix)

gym_refundacademy_refundtravel_cancel_feepostpartum_refundwedding_cancel_feerental_cancel_feestudyroom_refundlodging_cancel_feeshow_ticket_cancel_feemoving_cancel_feecar_rental_refundinsurance_withdraw_deadlinegift_certificate_refundsangjo_cancel_refundrealestate_brokerage_feegolf_cancel_feelate_interestloan_scheduleprepay_feeovertime_payseverancepayroll_slipfreelancer_taxlease_renewal

Inputs are described in openapi.json; guidance for AI agents is in llms.txt.

Error codes

401	The key is missing or invalid.
403	This key's plan does not include the API (widget key).
429	You have passed this month's call limit.

FAQ

Can I use it without a key?

tool.avenpa.com/api/calc is open without a key. This endpoint is the keyed one, with usage reporting and a monthly limit.

What happens past the limit?

You get 429 for the rest of the month. The counter resets on the 1st (UTC).

How much does it cost?

The beta is free of charge. Pricing will be set after the beta and announced in advance.

Are responses in English?

No. Inputs follow the OpenAPI spec, but the answer text and the legal basis are in Korean and follow Korean law.

Who is responsible for the results?

They are reference calculations. Contract terms and exemptions are not reflected.