You can run a local version of SlackerNews that connects to a sqlite database by running yarn run dev from the ./slackernews directory.
In order to log in via Slack, you need a redirect_uri that can't be localhost. We recommend ngrok, and using that to access your local dev env.
ngrok http --subdomain=you 3000
You can configure Google Auth and Slack by editing the .env.local file:
NEXT_PUBLIC_API_ENDPOINT=http://localhost:3000
SLACK_AUTH_REDIRECT_URI=https:/<ngrok or something>/login/callback
DB_URI="./slackernews.db"