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The Refresh token is to be used to retrieve a valid access token (e.g. when the current access token expires). You can change the expiry settings on this but you can also set this never to expire, only when it is revoked.

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Get OAuth Token

To make the initial authorization request for a user to grant your app access to their data (this is where your user is initially directed to a Saleforce.com authorization endpoint and logs in) you’d make the following request. The ClientID in the below call will be your consumer ID from the connected app. The redirect_url will be the Callback URL.

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