FinCalculator API

Free, public, edge-cached financial calculation endpoints for India. JSON responses, CORS open, no auth required. Built on the same engine that powers fincalculator.in — so the numbers you see here are the numbers your users see.

Quick start

Every endpoint is a plain GET with query params. Try one in your terminal:

curl 'https://fincalculator.in/api/v1/sip?investment=10000&interest=12&years=10'

Limits & caching

Responses are cached for 24 hours at the edge — same input returns instantly.
No rate limit today. We'll publish one before adding any.
CORS: Access-Control-Allow-Origin: *
Versioned at /api/v1/ — breaking changes will land at /v2/.

Endpoints

GET/api/v1/sip

Compute SIP future value, total invested, and total returns.

Parameters

Name	Type	Required	Notes
investment	number	yes	Per-period amount in ₹
interest	number	yes	Annual % return
years	number	yes
frequency	string	no	daily \| weekly \| monthly \| quarterly \| yearly (default: monthly)

Example

curl 'https://fincalculator.in/api/v1/sip?investment=10000&interest=12&years=10&frequency=monthly'

GET/api/v1/emi

Compute loan EMI, total interest, total payment, and (optionally) yearly breakup.

Parameters

Name	Type	Required	Notes
principal	number	yes
interest	number	yes	Annual % rate
years	number	yes
breakup	boolean	no	Set to "true" to include yearly amortization

Example

curl 'https://fincalculator.in/api/v1/emi?principal=8000000&interest=8.5&years=20'

GET/api/v1/step-up-sip

Compute Step-Up SIP returns where the contribution increases by a fixed % or amount each period.

Parameters

Name	Type	Required	Notes
initialInvestment	number	yes
stepUpValue	number	yes
interest	number	yes
years	number	yes
stepUpType	string	no	percentage \| amount (default: percentage)
stepUpFrequency	string	no	monthly \| yearly (default: yearly)

Example

curl 'https://fincalculator.in/api/v1/step-up-sip?initialInvestment=10000&stepUpValue=10&interest=12&years=15'

GET/api/v1/income-tax

Compute Indian income tax under old or new regime, including 87A rebate, surcharge with marginal relief, and 4% cess.

Parameters

Name	Type	Required	Notes
grossIncome	number	yes	Annual gross income in ₹
regime	string	no	old \| new-2024-25 \| new-2025-26 \| new-2026-27 (default: new-2026-27)
applyStandardDeduction	boolean	no	Set to "false" to skip standard deduction (default: true)

Example

curl 'https://fincalculator.in/api/v1/income-tax?grossIncome=1500000&regime=new-2026-27'

Using this in production?

We'd love to hear about it. Drop us a note via /contact — we'll keep you posted on schema changes and new endpoints.