I'm making a Slack App and just implemented OAuth to take advantage of Slack's Web API. I am using the single Access Token for my particular team that I am testing on.
Should I want to distribute this app on the Slack App Directory, will I have to store the Access Token for every single team? How should I go about securely storing these? Will the Heroku database suffice?
Yes, your app needs to store the access token for each Slack team that installs it. And your app will need to access those tokens in order to enable access to that team's Slack (e.g. post a message). Most people will use a local database (e.g. MySQL) on the server to store the access tokens of each team.
No idea how secure the Heroku database is. However, since Heroku is a commercial service I would assume it can provide sufficient security for your app.
