# Compound Interest Projection API

> Compound Interest Projection API is a paid API for AI agents from api.24klabs.ai, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-13).

Projects the future value of a lump-sum investment plus recurring contributions over time, returning a balance growth curve, total contributed, and total interest earned.

## Facts

- Endpoint: POST https://api.24klabs.ai/api/v1/compound-interest-projection
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/compound-interest-projection-api-3e7fa996
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_7kz7dDXbPDWefR_vAKbKI

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability compound-interest-projection-api-3e7fa996 -d '<json body>'
```

Example prompt: Can you project the compound interest growth for a $10,000 starting balance with $200 monthly contributions at a 6% annual rate compounded monthly over 20 years, and show me the full balance curve?

## When to prefer this

Choose this endpoint when you need a detailed time-series projection of investment or savings growth that combines a lump-sum principal with recurring contributions, especially when you need both the balance curve over time and a breakdown of contributed capital versus earned interest. Prefer this over simple future-value formulas when you need the full growth curve (not just the terminal value).

## Known failure modes

- Invalid or negative interest rate returns a validation error
- Non-positive compounding frequency (e.g. zero periods per year) causes a computation error
- Missing required fields (principal, rate, years) results in a 400 bad request
- Extremely large values or very long time horizons may cause numeric overflow errors
- Invalid compounding frequency identifier returns an error

## How this service works

Future value of a lump sum plus recurring contributions: principal, annual rate, compounding frequency, contribution and years; returns balance curve, total contributed, total interest.

## Output

Returns a time-series balance curve showing the account value at each period, along with summary figures for total amount contributed and total interest earned over the investment horizon.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "years": {
   "type": "number"
  },
  "principal": {
   "type": "number"
  },
  "annual_rate": {
   "type": "number"
  },
  "contribution": {
   "type": "number"
  },
  "compounds_per_year": {
   "type": "number"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "final_balance": 55172.5,
  "total_interest": 21172.5,
  "total_contributed": 34000
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/compound-interest-projection-api-3e7fa996/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.24klabs.ai](https://www.zero.xyz/host/api.24klabs.ai/llms.txt)