API Documentation

Integrate 197 RF & electronics calculators into your scripts, notebooks, and applications via a simple REST API. One endpoint, any calculator.

Quick Start

Get an API Key

Get a free API key on your dashboard (5 calculations/month free), or subscribe for more — see pricing for Pro ($9/mo, unlimited) and API tier ($19/mo, 10,000 calc/mo) options.

Call the Endpoint

POST to /api/py/v1/calculate with a slug and inputs.

Use the Results

Parse the JSON response with computed values, warnings, and errors.

curlExample request

curl -X POST https://rftools.io/api/py/v1/calculate \
  -H "Content-Type: application/json" \
  -H "x-api-key: YOUR_API_KEY" \
  -d '{"slug":"vswr-return-loss","inputs":{"vswr":2.0}}'

Authentication

Pass your API key via the x-api-key header. All requests to the calculate endpoint require an API key.

x-api-key: rfc_a1b2c3d4e5f6...

Free API keys include 5 calculations/month. API tier keys include 10,000 requests/month. Usage resets on the 1st of each month. Generate and manage keys from your dashboard.

Endpoints

POST/api/py/v1/calculate

Run any calculator with the given inputs and return computed values.

Auth: Required (x-api-key header)

Request Body

{
  "slug": "vswr-return-loss",
  "inputs": { "vswr": 2.0 }
}

Response

{
  "slug": "vswr-return-loss",
  "values": {
    "returnLoss": 9.5424,
    "reflectionCoefficient": 0.3333,
    "mismatchLoss": 0.5118,
    "reflectedPowerPct": 11.11
  },
  "warnings": [],
  "errors": []
}

curl

curl -X POST https://rftools.io/api/py/v1/calculate \
  -H "Content-Type: application/json" \
  -H "x-api-key: YOUR_API_KEY" \
  -d '{"slug":"vswr-return-loss","inputs":{"vswr":2.0}}'

GET/api/py/health

Health check endpoint — returns service status.

Auth: None

Response

{ "status": "ok", "service": "rfcalc-api" }

curl

curl https://rftools.io/api/py/health

Request & Response Schema

CalculateRequest

slugstringrequired

Calculator identifier (e.g. "vswr-return-loss")

inputsRecord<string, number>required

Key-value pairs of input parameters

CalculateResponse

slugstring

Echo of the calculator slug

valuesRecord<string, number>

Computed output values

warningsstring[]

Non-fatal warnings (e.g. out-of-range inputs)

errorsstring[]

Calculation errors (empty on success)

Try It

Interactive Playground

Calculator

Inputs (JSON)

API Key

Enter your API key to run queries. Get a free key on your dashboard →

Popular Calculator Slugs

There are 197 calculators available. Here are the most common ones. Browse the full list at /calculators.

Slug	Calculator	Example Inputs
`vswr-return-loss`	VSWR / Return Loss	`{ "vswr": 2.0 }`
`microstrip-impedance`	Microstrip Impedance	`{ "width": 1.2, "height": 1.6, "er": 4.4, "thickness": 0.035 }`
`dbm-watts`	dBm / Watts / dBW	`{ "dBm": 30 }`
`free-space-path-loss`	Free Space Path Loss	`{ "frequency": 2400, "distance": 100 }`
`skin-depth`	Skin Depth	`{ "frequency": 1000000, "conductivity": 58000000, "permeability": 1 }`
`wavelength-frequency`	Wavelength / Frequency	`{ "frequency": 2400 }`
`ohms-law`	Ohm's Law	`{ "voltage": 12, "resistance": 100 }`
`pcb-trace-width`	PCB Trace Width	`{ "current": 3, "thickness": 1, "tempRise": 10, "layer": "external" }`

Rate Limits

Tier	Requests/min	Monthly Quota	Price
Free (API key)	30	5 calc/mo	$0
Pro	60	Unlimited	$9/mo
API	120	10,000	$19/mo

When rate limited, the API returns 429 with a Retry-After header.

Error Codes

200Success — result returned in response body

400Bad request — invalid inputs or calculation error

401Unauthorized — invalid or quota-exceeded API key

404Not found — calculator slug does not exist

429Rate limited — too many requests per minute

Ready to integrate?

Get your API key and start making requests in under a minute. 10,000 requests/month, 120 req/min burst, all 197 calculators.

Get API Access — $19/mo Manage Keys

Or get a free key (5 calc/mo) from your dashboard — no credit card required.