Not free, since you still need a Kubernetes somewhere.<p>But at least 100% open-source and selfhostable.<p>It covers most of Herokus features.<p><a href="https://docs.kubero.dev/comparison-heroku/" rel="nofollow">https://docs.kubero.dev/comparison-heroku/</a>
Heroku's PostgreSQL is still free. As for dynos, the lowest tier is $5/mo for multiple apps (not production traffic of course, maybe for MVP), with custom domain support.