How to embed code to display it on the site?

Question

Toaster

What is used to embed and read the code on the site?
By type of code inserts here on the toaster:

# code
alert('Программный код');

<header>
  <nav>
  </nav>
</header>
<main>
  <header>
    <h1></h1>
  </header>
</main>
<footer>
  <address></address>
</footer>

Answer 1

prismjs.com/index.html

Answer 2

www.codelighter.com