Heroku alternatives that are 100% Open Source, no Open-Core
Of the 4 self-hosted Heroku alternatives, only Coolify and Dokku are 100% FOSS — CapRover and Dokploy are Open-Core. Here the auditability argument carries more weight than in other categories: a PaaS manages the credentials and secrets of every application you deploy through it, not just its own.
Tools that meet this intent
Alternative to Vercel, Netlify, Heroku
Self-hosted PaaS with a Vercel-like experience, a free alternative.
Alternative to Heroku
Open source mini-Heroku, deploy with git push.
Why being 100% FOSS matters here
Coolify (Apache-2.0) and Dokku (MIT) are fully FOSS projects, with no paid "Cloud" tier holding exclusive features. Dokploy is the clearest case of what's traded away by choosing Open-Core in this category: its own listing states Dokploy Cloud (the managed version) is paid, while the self-hosted version requires your own server — an explicit business incentive behind the project. The full installation and scope details for all 4 tools (Coolify, CapRover, Dokku, Dokploy) live on Heroku's self-hosted page — here we focus on why licensing matters specifically for this kind of software.
What you gain and lose versus the SaaS
Within the 100% FOSS subset, Coolify and Dokku are still very different from each other: Coolify is the more complete, polished option (one-click deploys, multi-server panel); Dokku is the more minimalist approach, no official web panel, deploying with a plain git push. FOSS licensing doesn't erase that scope difference — choosing "FOSS only" still leaves you deciding between a complete platform and a deliberately small tool.