API & MCP
Everything a person can do on Ledgerly Compound Growth Calculator, a program or AI agent can do with the same inputs and get the identical result.
HTTP API
POST https://ledgerlycompoundgrowth.usefulweb.app/api/v1/calculate– run Ledgerly Compound Growth CalculatorGET https://ledgerlycompoundgrowth.usefulweb.app/api/v1/tool– inputs, output schema, examples- OpenAPI 3.1: /openapi.json · /openapi.yaml
- Errors:
application/problem+json;422includes per-fielderrors.
Ledgerly Compound Growth Calculator
Compound interest with a starting amount, monthly contributions (at the start or end of the month, with a yearly raise), monthly, yearly or daily compounding, yearly fees and inflation. Shows the final balance, the same in today’s money, how much you paid in, how much fees cost including the growth they take away, the doubling time and a year-by-year table. Part of Ledgerly’s Debt & Growth.
| Field | Type | Default | Description |
|---|---|---|---|
currency | text | "EUR" | Currency. ISO code used for the labels, e.g. EUR, USD, GBP. |
startAmount | number | 10000 | Starting amount |
monthlyContribution | number | 200 | Added every month |
contributionTiming | select (end, start) | "end" | Added at the |
contributionIncreasePercent | number | 0 | Raise of the monthly amount (% per year) |
years | integer | 20 | Years |
annualReturnPercent | number | 6 | Return (% per year, before fees) |
compounding | select (monthly, yearly, daily) | "monthly" | Compounding |
feePercent | number | 0 | Yearly fees (% of the balance). Fund costs (TER), platform or advice fees, charged monthly on the balance. |
inflationPercent | number | 2 | Inflation (% per year) for today’s money |
Example request
10,000 plus 200 a month for 20 years at 6 %, 0.8 % fees
curl -X POST https://ledgerlycompoundgrowth.usefulweb.app/api/v1/calculate -H 'content-type: application/json' -d '{"currency":"EUR","startAmount":10000,"monthlyContribution":200,"years":20,"annualReturnPercent":6,"feePercent":0.8,"inflationPercent":2}'Every result contains
inputs (normalised, defaults applied), summary, result (validated against the published schema), units, assumptions, sources, warnings, computedAt and links.
MCP (Model Context Protocol)
- Streamable HTTP endpoint:
https://ledgerlycompoundgrowth.usefulweb.app/mcp– protocol revisions 2026-07-28 (stateless) and 2025-11-25 / 2025-06-18 / 2025-03-26 (initialize handshake). - Tools:
ledgerly_compound_growth - Local stdio connector:
node src/mcp-stdio.ts --tool=ledgerly-compound-growth
{
"mcpServers": {
"ledgerly-compound-growth": { "type": "http", "url": "https://ledgerlycompoundgrowth.usefulweb.app/mcp" }
}
}