Compound Interest / Future Value Calculator

Future value, total contributions and interest with optional periodic deposits.

Free tier eligible — 500 calls/month with a free key from /pricing; x402 pay-per-call above quota.

Parameters

Parameter	Type	Required	Description
`principal`	number	optional	Starting principal in USD
`annual_rate_pct`	number	required	Annual interest rate as a PERCENT (6 = 6%)
`years`	number	required	Number of years
`compounds_per_year`	integer	optional	Compounding periods per year (default 12)
`contribution`	number	optional	Deposit added each compounding period, USD

Call it over MCP (JSON-RPC 2.0)

curl -s https://wingmanprotocol.com/mcp \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json, text/event-stream' \
  -d '{"jsonrpc": "2.0", "id": 1, "method": "tools/call", "params": {"name": "compound_interest", "arguments": {"annual_rate_pct": 0.07, "years": 30}}}'

Or plain HTTP

curl -s https://wingmanprotocol.com/tools/compound_interest \
  -H 'Content-Type: application/json' \
  -d '{"annual_rate_pct": 0.07, "years": 30}'

Try it live

Edit the JSON and run it — this POSTs to https://wingmanprotocol.com/tools/compound_interest from your browser.

This tool is x402-metered — agents pay per call with USDC on Base. The 402 response below is the standard x402 payment-requirements envelope: sign the EIP-3009 authorization and retry with the X-Payment header, or get a free key at /pricing (500 calls/month, no card, no crypto).