If you verify with a credit card, a single dyno can run for as many hours as you like -- it can perpetually serve HTTP requests for years and years -- but it will be automatically turned off every few hours, with some latency on the first request to boot it back up.
I would say this kind of free tier is quite powerful. It even had free Redis and PostgreSQL. But it had some horrendous periods of downtime and bugs that affect the paying customers just as badly. So ironically the free Heroku experience in 2022 leads you to the conclusion that it's the worst service you could pay for, but the best service you could mooch off of (aside from fly.io and similar) -- which may be counterproductive for Heroku's marketing.
I would say this kind of free tier is quite powerful. It even had free Redis and PostgreSQL. But it had some horrendous periods of downtime and bugs that affect the paying customers just as badly. So ironically the free Heroku experience in 2022 leads you to the conclusion that it's the worst service you could pay for, but the best service you could mooch off of (aside from fly.io and similar) -- which may be counterproductive for Heroku's marketing.