The Greek Capital Letter Beta symbol (Ξ). Copy and paste it, or use its Unicode, HTML, and CSS codes.
More from Greek Letters.
The quickest way is to copy Ξ from this page and paste it anywhere. You can also insert it with its Unicode, HTML, or alt code listed above.
Ξ is U+0392 (decimal 914).
Use Β in HTML to render Ξ on a web page.
On Windows you can type it with Alt+914 (hold Alt and enter the number on the numeric keypad).
Yes β copying is completely free and unlimited, and works right in your browser with no sign-up.