US Salary & Cost of Living API + MCP Server (Free Tier)

The Kultranz API turns the data engine behind this site into clean JSON: 2026 take-home pay for all 50 states + DC, cost-of-living comparisons across 50 metros, and real BLS wage percentiles by job and city. Nine REST endpoints plus a remote MCP server, with every number traceable to a named federal release: BLS OEWS wages, BEA Regional Price Parities, Census ACS housing and income, IRS 2026 tax rules. No estimates, no scraping, no guesswork - the same engine that powers the calculators on this site, exposed for developers.

Free to start: 25 requests a day, no key, no signup, no credit card.

Start free

Base URL: https://api.kultranz.com. One curl is the whole onboarding:

curl "https://api.kultranz.com/paycheck?salary=120000&state=CA&filingStatus=single"

What a call returns

A live response from GET /cost-of-living - two metros, their BEA price parities, and the salary you would need in the second city to hold purchasing power constant:

{
  "data": {
    "from": { "city": "Austin, TX", "rpp": 98.1 },
    "to": { "city": "San Francisco, CA", "rpp": 115.6 },
    "equivalent_salary": 117838.94,
    "gap_pct": 17.84
  },
  "meta": {
    "source": "BLS OEWS + BEA RPP + U.S. Census ACS + IRS (via kultranz.com)",
    "vintage": "2026",
    "year": 2026
  }
}

Every response carries the same meta envelope naming the source agencies and the data vintage, so a downstream product can display provenance without hard-coding it. Errors return { "error": { "code": "...", "message": "..." } } with the appropriate HTTP status.

Pricing

Buy the $5 Data Pass →

The Data Pass is direct billing - one payment, yours for the life of the API, no subscription to cancel. After the first 500 are sold, the pass becomes $5/month for everyone after.

Prefer a marketplace? The same API is listed on RapidAPI, where keys, metering and billing are handled for you: Pro at $10/month per 100,000 requests. Ultra and Mega are mid-reprice on the marketplace dashboard: they bill $49/month and $199/month today, moving to $15/month and $20/month, so check the listing before subscribing. Direct billing via the $5 Data Pass is live now and stays the cheap route.

Building a product on the data? Data licensing covers the maintained feed, bulk exports, commercial redistribution and white-label rights: Business at $19/mo and Redistribution at $20/mo (launch pricing), both self-serve at the Business checkout and the Redistribution checkout.

Need salary data for a negotiation? The $19 Salary Negotiation Brief (our product) turns the same BLS and BEA data into a one-page counter-offer packet. Starting one instead? The free counter-offer email template on the same page costs an email address, not $19.

Disclosure: the Data Pass and the RapidAPI listing are both ours - this is our API, sold direct and through a marketplace. Questions or bulk/commercial needs: [email protected].

The MCP server at /mcp is free with a generous 200 tool calls per day per visitor. It only exposes what the site’s public calculators already give away.

REST endpoints

Parameter details:

• /paycheck - salary (required, > 0), state (required, two-letter code, 50 states + DC), filingStatus (single | mfj, default single), pretax401k (optional, >= 0).
• /cost-of-living - fromCity, toCity (required, exact metro names as returned by /col-index), salary (default 100000), rich=1 adds a per-category monthly cost breakdown for both cities.
• /tax-brackets - state (optional; omit for federal only), filingStatus. Returns the standard deduction and the full bracket ladder.
• /col-index - city optional; omit for the full 50-metro table.
• /salaries - job and/or city (partial match, e.g. nurse, Chicago), optional state. Up to 100 records, 16 fields each: percentiles (10th/25th/median/75th/90th), averages, employment, and the metro’s cost-of-living context.

Examples

Take-home pay (curl)

curl "https://api.kultranz.com/paycheck?salary=120000&state=CA&filingStatus=single&pretax401k=10000"

{
  "data": {
    "gross": 120000,
    "pretax": 10000,
    "taxable_income": 93900,
    "federal_tax": 15370,
    "social_security": 7440,
    "medicare": 1740,
    "state_tax": 6153.42,
    "total_tax": 30703.42,
    "net": 79296.58,
    "effective_rate": 25.59
  },
  "meta": { "source": "BLS OEWS + BEA RPP + U.S. Census ACS + IRS (via kultranz.com)", "vintage": "2026", "year": 2026 }
}

Cost of living (curl)

curl "https://api.kultranz.com/cost-of-living?fromCity=Austin,%20TX&toCity=San%20Francisco,%20CA&salary=100000"

Salary percentiles (curl)

curl "https://api.kultranz.com/salaries?job=nurse&city=Chicago"

{
  "data": {
    "count": 1,
    "records": [
      {
        "job_title": "Registered Nurse",
        "job_code": "29-1141",
        "city": "Chicago",
        "state": "IL",
        "avg_salary": 90810.0,
        "salary_10th": 67560.0,
        "salary_25th": 79590.0,
        "salary_median": 85160.0,
        "salary_75th": 102440.0,
        "salary_90th": 107980.0,
        "national_avg": 94480.0,
        "employment": 102330,
        "rpp_all_items": 103.595,
        "median_rent": 1380.0,
        "median_home_value": 315200.0,
        "city_median_income": 75134.0,
        "city_population": 2707648
      }
    ]
  },
  "meta": { "source": "BLS OEWS + BEA RPP + U.S. Census ACS + IRS (via kultranz.com)", "vintage": "2026", "year": 2026 }
}

Python

import requests

BASE = "https://api.kultranz.com"

r = requests.get(f"{BASE}/paycheck", params={
    "salary": 120000, "state": "CA", "filingStatus": "single"
})
pay = r.json()
print(pay["data"]["net"], "take-home on", pay["data"]["gross"])

r = requests.get(f"{BASE}/cost-of-living", params={
    "fromCity": "Austin, TX", "toCity": "San Francisco, CA", "salary": 100000
})
col = r.json()["data"]
print(f'${col["equivalent_salary"]:,.2f} in {col["to"]["city"]} '
      f'= $100,000 in {col["from"]["city"]} ({col["gap_pct"]:+.2f}%)')

MCP server

The same data engine is exposed as a remote MCP server - no install, no local process, no API key.

The five tools

* required. City names must match list_metros exactly (e.g. "Austin, TX"); call list_metros first to resolve them. Tool results carry both content (JSON text) and structuredContent with the same data + meta envelope as the REST API.

Why five tools and not nine: the four generic calculators (compound interest, net worth, debt payoff, budget) are arithmetic any model can already do. These five are the ones that need the 50-state tax engine, BEA parities or BLS wage tables - things a model genuinely cannot compute by itself.

curl

# 1. initialize
curl https://api.kultranz.com/mcp \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"curl","version":"0"}}}'

# 2. tools/call (after the initialized notification)
curl https://api.kultranz.com/mcp \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"get_take_home_pay","arguments":{"salary":120000,"state":"TX"}}}'

Python client

import requests

MCP = "https://api.kultranz.com/mcp"

def rpc(id, method, params=None):
    body = {"jsonrpc": "2.0", "id": id, "method": method}
    if params is not None:
        body["params"] = params
    return requests.post(MCP, json=body, timeout=30).json()

# handshake: initialize -> initialized notification -> call tools
rpc(1, "initialize", {
    "protocolVersion": "2025-06-18",
    "capabilities": {},
    "clientInfo": {"name": "example", "version": "0"},
})
requests.post(MCP, json={"jsonrpc": "2.0", "method": "notifications/initialized"})

result = rpc(2, "tools/call", {
    "name": "compare_cost_of_living",
    "arguments": {"fromCity": "Austin, TX", "toCity": "San Francisco, CA", "salary": 100000},
})
data = result["result"]["structuredContent"]["data"]
print(f'${data["equivalent_salary"]:,.2f} needed in {data["to"]["city"]}')

Client setup

Claude Code:

claude mcp add --transport http kultranz https://api.kultranz.com/mcp

Claude Desktop: Settings -> Extensions -> Connectors -> Add custom connector. Name kultranz, URL https://api.kultranz.com/mcp, no key.

Cursor (.cursor/mcp.json):

{
  "mcpServers": {
    "kultranz": { "url": "https://api.kultranz.com/mcp" }
  }
}

Windsurf (~/.codeium/windsurf/mcp_config.json):

{
  "mcpServers": {
    "kultranz": { "serverUrl": "https://api.kultranz.com/mcp" }
  }
}

Then just ask: “what does a nurse earn in Chicago, adjusted for cost of living?” or “compare $120k take-home in Texas vs California”.

Data & limits

The honest version, because you should know what you are building on:

• Coverage: 50 US metro areas and 20 occupations (1,000 job x metro rows) in the salary dataset; 51 tax jurisdictions (50 states + DC). This is a curated dataset, not every BLS occupation. The full metro list is one call away: GET /col-index.
• Vintage: the tax engine is 2026 - IRS Rev. Proc. 2025-32 brackets, $16,100/$32,200 standard deduction, $184,500 Social Security wage base, state brackets per Tax Foundation’s 2026 compilation. Cost-of-living uses BEA Regional Price Parities (US average = 100); wages are BLS OEWS as named on the methodology page. Each government release is annual; we ship refreshes within 30 days of publication.
• Nulls are real: a few metros (e.g. Arlington, TX and Cleveland, OH) lack Census ACS housing fields; those come back null rather than an interpolated guess. Every response’s meta names the sources and vintage so you can label provenance in your own product.
• Tax model scope: estimates, not tax advice. It covers federal income tax, FICA and state income tax for single and mfj. It excludes local/city income taxes (NYC, Philadelphia), credits and itemized deductions. Washington and New Hampshire levy no tax on wage income and are modeled as no-tax. A handful of states’ MFJ standard deduction is approximated at 2x single where the exact figure was unavailable - flagged in the methodology.
• No fabrication: if a number is not in a source, it is null, not invented. The calculations (equivalent salary, take-home, affordability ratios) are documented formulas on the methodology page.

Commercial & bulk licensing

Building a product on this data? Beyond the metered API, the full dataset is licensed directly: bulk JSON/CSV exports, commercial-use and white-label rights, annual refresh as BLS/BEA/Census publish, and a data-refresh SLA. The per-record shape is public - 16 fields per job x metro row, each traceable to a named federal release (see the free CC BY dataset for the columns). Business ($19/mo) and Redistribution ($20/mo) are self-serve checkout: start Business or start Redistribution. For volume pricing or custom terms, email [email protected] for a quote and an evaluation dataset.

Try it

The calculators on this site call these endpoints under the hood. Run the paycheck calculator, the cost-of-living tool, or browse salaries by job to see the data in action - then hit the API directly when you’re ready to build.