Behind many expensive SaaS products sits an ordinary self-hosted open-source project — the only difference is who deployed it and whose infrastructure it runs on. Here are five of them: what each one replaces, why you would host it yourself, and how to adapt it to your task quickly with Claude.
Why host it yourself instead of paying for SaaS
Three reasons come up most often: control over the data (everything stays on your own infrastructure), customization flexibility (the code is open, so you can change the logic for a specific client) and predictable cost (you pay for a server, not for a plan that grows with your user count). None of the projects below are cracked or grey copies — they are legitimate open-source alternatives with their own licenses.
Cal.com — your own booking system
Cal.com is the open-source counterpart to Calendly: a calendar, meeting slots, integrations with external services, and full branding control instead of someone else's logo in the corner.
Fork the repository, deploy it on your server, and you get a product entirely inside your own infrastructure, without the limits of a third-party free plan.
Repository: github.com/calcom/cal.com
Supabase — a backend in a weekend
Supabase covers the technical foundation of an app: a Postgres database, user authentication and auto-generated APIs on top of your data schema.
It saves weeks of infrastructure work — instead of writing a backend from scratch you can go straight to building product logic on top of a ready database, auth and API.
Repository: github.com/supabase/supabase
Plausible Analytics — analytics without tracking
Plausible is a lightweight alternative to Google Analytics with privacy by default: no cookie banners, no user data handed to third parties, and a simple readable dashboard.
You install it on the client's own server as part of the service — the data stays in the site owner's infrastructure instead of leaking into someone else's ad ecosystem.
Repository: github.com/plausible/analytics
Chatwoot — customer chat without a subscription
Chatwoot covers what companies pay Intercom for: a conversation list, tickets, auto-replies, and integrations with the website and messengers.
It deploys on your server and embeds into the client's site without a monthly fee per support agent — a one-time setup instead of a growing bill.
Repository: github.com/chatwoot/chatwoot
Coolify — your own Vercel on your own server
Coolify is an open-source alternative to Heroku, Netlify and Vercel: a platform for deploying applications without vendor lock-in and without a bill that grows with the project's traffic.
It works as the base for your own deployment platform when full control over infrastructure matters — from where the server physically sits to how the pipeline is configured.
Repository: github.com/coollabsio/coolify
How to deploy and adapt them with Claude
The general flow: clone the repository, bring it up with Docker Compose (all five ship ready configurations in their docs), then customize for the task. This is exactly where Claude earns its keep: you describe the data model or the logic you need to add on top of the ready platform (a custom field in Cal.com, your own table in Supabase, a reply template in Chatwoot) and you get a migration or the changed code instead of rewriting the platform from scratch. A prompt along the lines of "here is the project schema, here is the task, propose the minimal change that fits the existing architecture" works far more reliably than "add feature X" with no context.
How we do it
Our qvib engine for generating code and sites is a living example of a product grown from a similar open-source foundation with an automation layer on top. We regularly deploy and test projects like these ourselves before recommending them in the knowledge base — not a retelling of the docs, but a check in practice.
Related links
- Open-source service roundups: qvib.pro/arsenal/docs/podborka-opensource-servisov/
- Vibe coding from scratch: qvib.pro/arsenal/skills/vaib-koding-s-nulya/
- Prompts for deployment and customization: qvib.pro/arsenal/prompts/deploy-i-kastomizaciya-opensource/