PlatformIO being open-source doesn’t really mean anything. The problem isn’t the license – it’s the dependency. Even though the core code is open, nearly everyone depends on PlatformIO’s cloud-hosted registry, platform definitions, telemetry-connected VSCode extension, and online updating system. So the fact remains: the Arduino ecosystem has already normalized cloud-based infrastructure for compiling and deploying simple microcontroller code.

Picture this: Your CI pipeline, your board definitions, your library versions, they all come from their servers. This is very similar to the typical open-source vendor lock-in that you see from Microsoft, Oracle and others. Even if (some of) the code is available you’re locked in.

The PlatformIO Core is open-source, but for it to work you depend on:

• The PlatformIO Registry
• Cloud-hosted package indexes – library installation from the cloud registry and automatic updates and platform definitions stored server-side
• Version metadata distributed from their servers
• Cloud Remote, cloud debugging, “PIO Account” features
• VSCode extensions that phone home for updates and telemetry

This means that in practice, users become dependent on PlatformIO maintaining and serving these resources. If PlatformIO’s servers are gone tomorrow, many builds that rely on dynamic platform and library fetching break.

Even if your builds have it all locally cached, how long do you think that will last? It just takes a certificate that signs some piece of the locally installed PlatformIO tools to expire OR some part of that system decides to invalidate your local copy of some package and you won’t be able to build anymore.

PlatformIO is Apache 2.0 (mostly), that means you can self-host and/or fork it in theory, but can you really?

• PlatformIO doesn’t provide clear instructions on how do replicate their ecosystem
• The PlatformIO ecosystem was designed in a way that makes it very hard, next to impossible, to actually get all the data, metadata, configurations and whatnot required to replicate it
• Even if you’re able to get all the server-side hosted stuff, you’ll still have to heavily modify the plugin / IDE code and tools to make use of alternative servers
• CI systems rely on the servers hosted by PlatformIO – not much visibility is available into those

In essence reproducing the full “Platform + Boards + Libraries” database is nontrivial, so the dependency remains centralized. Even if the tool is open-source, the ecosystem around it was designed to make you dependent on a single service provider (them).

Unlike the classic Arduino ecosystem, PlatformIO encourage “cloud-first” behavior – the user experience is built around being online continuously. PlatformIO essentially shifted the Arduino ecosystem quietly from a offline-first workflow to one that assumes constant connectivity. In the classical Arduino tools you can easily install the IDE and copy libraries into a directory and everything will work.

“Open-source” but:

• PlatformIO controls the official registry
• PlatformIO decides platform definitions
• PlatformIO maintains the dominant VSCode plugin
• PlatformIO can introduce features that require accounts or cloud usage
• PlatformIO sets the roadmap and defaults
• There’s no community-owned standard or neutral foundation like the Linux kernel

With PlatformIO you’re hostage of a platform carefully designed to take your over workflow in a way that isn’t reproduceable if the company goes under. At any point they can push you to more cloud subscriptions and dependencies and you’ll pay or not be able to compile.