Facebook login - how to develop on both localhost and in production?

After I have worked with this for ~6 months, I have found a solution which works really well, based on the other two answers.

In Facebook I add two apps:

• Production app
• Dev app

Then, in my web.config app settings I have:

<!--Prod-->
<add key="_FacebookApiId" value="id"/>
<add key="_FacebookApiSecretId" value="secret_id"/>
<!--Dev-->
<add key="FacebookApiId" value="dev_id"/>
<add key="FacebookApiSecretId" value="dev_secret_id"/>

Which of course is read through a helper-class.

Then it works seamlessly on both production and localhost, and both myself and my team is happy.

Update: As of 2018 the path to this setting is now Products > Facebook Login > Settings > Client OAuth Settings the rest of this answer is still valid.

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There is a better way. You just need to add valid callback URL's for your localhost to Settings > Advanced > OAuth Settings.

This method allows you still have your production website URL while allowing oauth from dev, staging, production, etc.