Financial calculators and developer tools as an API

Building an app and need calculations? No need to write formulas from scratch. Send a request, get the result as clean JSON. Loan schedules, compound interest, ROI, hash generators, conversions and more. You focus on your product, we handle the math.

How does it work?

Send data, get results. Below is an example of a loan schedule calculation in three languages.

# Calculate loan repayment schedule
$ curl https://api.liczgrupa.pl/v1/tools/loan-amortization/run \
    -H "Authorization: Bearer $LG_API_KEY" \
    -d '{"principal": 300000, "annual_rate": 7.5, "years": 25}'

{
  "request_id":   "01KPW8...",
  "tool":         "loan-amortization",
  "credits_used": 1,
  "result": {
    "monthly_payment": 2217.42,
    "total_interest":  365226.00,
    "total_paid":      665226.00,
    "schedule":        [/* 300 rows */]
  }
}

# pip install requests
import requests

resp = requests.post(
    "https://api.liczgrupa.pl/v1/tools/compound-interest/run",
    headers={"Authorization": f"Bearer {API_KEY}"},
    json={"principal": 10000, "rate": 5.0, "years": 10}
)

data = resp.json()
print(f"Final value: {data['result']['future_value']} PLN")
# Final value: 16288.95 PLN

const res = await fetch(
  "https://api.liczgrupa.pl/v1/tools/roi-calculator/run",
  {
    method: "POST",
    headers: {
      "Authorization": `Bearer ${process.env.LG_API_KEY}`,
      "Content-Type": "application/json",
    },
    body: JSON.stringify({ investment: 50000, returns: 68000 }),
  }
);

const { result } = await res.json();
console.log(`ROI: ${result.roi_percent}%`);
// ROI: 36%

Designed for AI agents

We're building an MCP server. Claude, ChatGPT and Cursor will be able to use calculators as built-in tools. The agent asks, the API calculates, the user gets an accurate result.

Claude Desktop configuration

{
  "mcpServers": {
    "liczgrupa": {
      "url": "https://api.liczgrupa.pl/mcp"
    }
  }
}

Planned API tools

The API is under development. Below are the tools we plan to launch first.

Compound interest

compound-interest - calculate future value with compounding

Loan amortization

loan-amortization - repayment schedule with principal and interest

ROI / NPV / IRR

roi-calculator, npv, irr - return on investment and profitability analysis

Hash and Base64

hash-generator, base64 - SHA-256, MD5, encoding and decoding

JSON and conversions

json-validator, unit-converter - validation, formatting, conversion

Currency converter

currency-converter - convert currencies using live exchange rates

Frequently asked questions

How much does LiczGrupa API cost?

You'll get a free API key with 1,000 calls per month for testing. No card, no commitment. Premium plans will be announced before launch.

What calculators are available via the API?

Financial calculators (compound interest, loan amortization, ROI, NPV, IRR), developer tools (SHA/MD5 hash, Base64, JSON validation) and unit converters.

Will the API work with AI agents?

Yes, we're building an MCP server. Claude, ChatGPT and Cursor will be able to use calculators as built-in tools without additional configuration.

When will the API be available?

We're working on the API. Sign up for early access - we'll notify you by email when it's ready.