EveryCalc

io.github.xOyabunxv1.0.0Updated Oct 10, 2026

8 free finance calculators as MCP tools: mortgage, refinance, loans, interest, salary, tips.

VerifiedStreamable HTTPWeb executableFinanceProductivity & Workflow

Overview

AI-generated overview

EveryCalc exposes eight free personal-finance calculators as MCP tools, covering mortgages, refinancing, loans, interest, salary, tips, and percentages.

What it does
It provides eight calculator tools: mortgage payment breakdowns (principal, interest, tax, insurance, PMI, HOA), refinance break-even and lifetime savings, home affordability via the 28/36 rule, amortizing loan payments, compound interest with monthly contributions, percentage math, tip and bill splitting, and salary conversions between hourly, weekly, biweekly, monthly, and annual pay. Each result includes a calculator_url deep link to the matching interactive calculator. A parallel REST API exposes the same calculations.
When to use it
Useful when an assistant needs quick, consistent personal-finance arithmetic — estimating a mortgage or loan payment, comparing a refinance, checking affordability, projecting compound interest, splitting a bill, or converting a salary — without the user doing the math by hand.
Requirements
A remote Streamable HTTP endpoint at no API key, signup, or local install for the hosted version. Self-hosting requires Node 18+ and wrangler, deployed as a Cloudflare Worker.
Before you install
The tools only compute numbers from the inputs supplied; results are estimates and not financial advice. Inputs are sent to a third-party hosted service. No credentials, payments, or write actions are involved.

Installation

In SourceWeft

  1. Open EveryCalc in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Web executable via Streamable HTTP. Remote servers run from the web runtime once configured in a workspace.

Other MCP clients

Add this to your client's mcpServers config.

{
  "mcpServers": {
    "everycalc": {
      "type": "http",
      "url": "https://everycalc.xyz/mcp"
    }
  }
}

README

EveryCalc

Free finance calculators for every part of life, exposed as a REST API and an MCP server so AI assistants can do the math for you.

Live site: https://everycalc.xyz API docs (OpenAPI): https://everycalc.xyz/api/v1/openapi.json MCP endpoint: POST https://everycalc.xyz/mcp (Streamable HTTP, no auth)

What it is

EveryCalc is a collection of interactive personal-finance calculators. This repo hosts the server code that powers two machine-friendly interfaces on top of those calculators:

  1. REST API at everycalc.xyz/api/v1/* — plain GET endpoints, JSON in and out.
  2. MCP server at POST everycalc.xyz/mcp — eight calculator tools for Model Context Protocol clients (Claude, Cursor, and friends).

No API key. No signup. No local install for the hosted version.

Every tool result includes a calculator_url deep link to the matching interactive calculator on everycalc.xyz, so users can explore the numbers visually after the assistant does the math.

The 8 tools

ToolWhat it computes
calculate_mortgageMonthly payment breakdown: principal and interest via the amortization formula, plus property tax, homeowner insurance, PMI, and HOA
calculate_refinanceRefinance break-even month and lifetime savings
calculate_affordabilityHome affordability via the 28/36 rule
calculate_loanAmortizing loan payments
calculate_compound_interestCompound interest projections with monthly contributions
calculate_percentagePercentage calculations
calculate_tipTip and bill splitting
calculate_salarySalary conversions between hourly, weekly, biweekly, monthly, and annual pay

Use the hosted MCP server

Add this to your MCP client config:

json
{  "mcpServers": {    "everycalc": {      "url": "https://everycalc.xyz/mcp"    }  }}

That is the whole setup. The server is remote (Streamable HTTP), so there is nothing to install.

Use the REST API

All endpoints are GET with query parameters. Example:

GET https://everycalc.xyz/api/v1/calculate/mortgage?home_price=400000&down_payment_pct=20&annual_rate_pct=6.5&term_years=30

Response:

json
{  "ok": true,  "tool": "calculate_mortgage",  "inputs": { "homePrice": 400000, "annualRatePct": 6.5, "termYears": 30, "...": "..." },  "results": {    "loan_amount": 320000,    "down_payment_usd": 80000,    "monthly_principal_interest": 2022.62,    "monthly_total": 2022.62,    "total_interest": 408142.36,    "total_cost": 808142.36  },  "calculator_url": "https://everycalc.xyz/mortgage-calculator/"}

Available endpoints (full spec in openapi.json):

  • GET /api/v1/health
  • GET /api/v1/calculate/mortgage
  • GET /api/v1/calculate/refinance
  • GET /api/v1/calculate/affordability
  • GET /api/v1/calculate/loan
  • GET /api/v1/calculate/compound-interest
  • GET /api/v1/calculate/percentage
  • GET /api/v1/calculate/tip
  • GET /api/v1/calculate/salary
  • GET /api/v1/openapi.json

Errors return {"ok": false, "error": {"code": "...", "message": "...", "field": "..."}} with an appropriate HTTP status.

Run it yourself

The server is a Cloudflare Worker. The calculation math lives in src/engine.js as pure functions (no I/O), shared by the REST handlers and the MCP handlers in src/index.js.

Prerequisites: Node 18+, wrangler.

bash
npm install -g wranglerwrangler login# point [assets] directory at your static-site build, then:wrangler deploy

The OpenAPI document is generated from the same handlers, so API docs never drift from behavior.

Tests

bash
npm test

test/test.mjs exercises the REST endpoints against the pure math functions; test/test-mcp.mjs exercises the MCP tool handlers. All green as of the last deploy.

MCP registry

This repo includes server.json, the manifest for the official MCP registry.

License

MIT. See LICENSE.

Source: README.md at commit 69b7759

Tools

0
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Version history

1
  1. v1.0.0LatestOct 10, 2026