The Bitly platform allows you to connect both your Twitter and Facebook accounts to share directly from the platform!
To connect these account start by clicking on the hamburger menu in the top right hand corner of the dashboard. Click on "Settings" then "Social Sharing". You will have the option to connect your Facebook and Twitter accounts.
Each Social platform will prompt you to enter your credentials, then you'll either click on "Log In" or "Authorize app".
Once you have your accounts connected. You can share your Bitlinks by clicking on the “Share” button in the Bitinks section.