Healthchecks.io is a free and open source service for monitoring your cron jobs, background processes and scheduled tasks. Before adding Slack integration, please log into Healthchecks.io:
After logging in, go to the Integrations page, and click on Add Integration next to the Slack integration.
Click on the "Add to Slack" button, and you should be on a page that says "Healthchecks.io would like access to your Slack team". Select the team you want to add the Healthchecks.io integration app to.
You should now be on a page that says "Healthchecks.io would like access to TEAM NAME". Select the channel you want to post Healthchecks.io notifications to.
That is all! You will now be redirected back to "Integrations" page on Healthchecks.io and see the new integration!