Quickstart

1. Get an API key

Sign up at exactcalcs.com/dev — every account starts on the free plan (100 calculator loads as a one-time trial, no card required). Your API key is shown on that dashboard once you're signed in.

2. Drop the snippet on a page

No build step, no API call to write yourself — the script handles calling the API and rendering the calculator.

<div data-exactcalcs-widget="bmi" data-api-key="YOUR_API_KEY"></div>
<script src="https://exactcalcs.com/exactcalcs-widget.js" async></script>

Swap bmi for any ID from GET /v1/calculators.

3. Confirm it worked

Reload the page. A rendered calculator means the request to /v1/widget/verify succeeded. A small "Calculator Offline" message instead means the key, domain, or quota check failed — see Errors & rate limits for what each reason means and how to fix it.

Next

Embedding a calculator covers theming and every snippet option; POST /v1/calculate/:calcId covers calling the math directly, with no widget at all.