title: Sharing links from website to messenger: is the app_id parameter required?
body: <p>I want to implement social sharing buttons for my website. One of them should be for the facebook messenger.</p>
  
  <p>I've searched everywhere to see if the <code>app_id</code> prop in the url params is required or optional. Here is the example from the official documentation:</p>
  
  <p><code>&lt;a href=”fb-messenger://share/?link= https%3A%2F%2Fdevelopers.facebook.com%2Fdocs%2Fsharing%2Freference%2Fsend-dialog&amp;app_id=123456789”&gt;Send In Messenger&lt;/a&gt;</code></p>
  
  <p>The official documentation (<a href="https://developers.facebook.com/docs/sharing/messenger/web/" rel="nofollow noreferrer">https://developers.facebook.com/docs/sharing/messenger/web/</a>) doesn't say anything on the topic so I decided to ask this question here.</p>
  
  <p>Can anyone help me with this? Thanks!</p>