Three steps to a live demo that requires only a modern browser, not installation, nor plugins.

1. Develop a working version of a Mathematica Manipulate in a desktop installation or the Wolfram Cloud.

Here's one, the familiar Black-Scholes formula for option pricing.

manipulate code

2. Do a CloudDeploy to obtain a unique URL. The result is (try it out!):

3. Use EmbedCode on the cloud object from step 2 to generate embeddable HTML, and insert it into your web page

The whole process takes only a couple of minutes. Here's the result, a live, interactive demo:


Note: you may have to allow third-party cookies (for for this to work.