Open Source Is Not the Same as Owning Your Stack
Using open source software does not mean you own your stack. If a vendor still runs it and holds your data, you are as locked in as with any SaaS. Here is why.
Running on open source software does not mean you own your stack. People treat the two as the same thing and get burned. Open source is about the license on the code. Ownership is about who runs the software and who holds the data. You can build your entire product on open source and still be completely locked into a vendor, because a managed service running open source on your behalf can trap you exactly as hard as any proprietary SaaS. The code being open is nice. It is not the thing that sets you free. What sets you free is control of the deployment and the data underneath it.
Why open source alone does not free you
The open license means you could, in theory, run the software yourself. It says nothing about whether you actually do. When a vendor runs an open source database or search engine or queue for you as a managed service, your data lives on their infrastructure, your app talks to their endpoint, and leaving means the same migration it would take to leave any platform. The source being public does not shrink your data gravity or unwire your integrations, which is why data gravity is the real lock-in regardless of the license on the code.
Worse, managed vendors add proprietary layers on top of the open core: their own management API, their own scaling behavior, their own console. Build against those and you are locked into the vendor even though the engine underneath is open. The open part is not the part you depend on. The vendor's wrapper is.
Where open source actually does help
Open source gives you one thing that genuinely matters: the right to run it yourself. That right is the escape hatch. If a proprietary SaaS decides to triple its price or shut down, you are stuck. If a managed open source service does the same, you can, in principle, take the same software and run it on your own infrastructure, because the engine is available to everyone. That optionality is real and worth paying attention to. It is the difference between a vendor you can escape and one you cannot.
But optionality is only worth something if you can exercise it. The right to self-host is theoretical until you have the data and the ability to stand the thing up elsewhere. That is why the license is the beginning of ownership, not the end of it.
Watch the license traps
Not all "open" is open, either. Many projects use source-available or business-source licenses that look open but restrict exactly the commercial self-hosting you would rely on to escape. And open-core models keep the features you actually need behind a proprietary paid tier, so the open part is a demo and the lock-in lives in the closed part. I go through these in open core and BSL license traps to watch for. Read the license before you count on the escape hatch, because the escape hatch may be licensed shut.
What ownership actually requires
To own your stack, you need three things, and the open license is only one of them. You need software you are legally allowed to run. You need to actually control the deployment, on infrastructure you hold. And you need your data in a portable form underneath, not trapped in the vendor's managed layer. This is the same standard as what no vendor lock-in actually requires: the license, the deployment, and the data all have to be yours.
I run the portfolio on open source almost everywhere, but the freedom does not come from the license. It comes from running that software myself on infrastructure I control through HostSSH, with the data on boxes I own. Open source made that possible. It did not make it true. If someone else runs the open source and holds your data, you have chosen a vendor with a nicer exit, not ownership. Take the extra step, or admit you are renting, just with better paperwork.