In case I haven't made this abundantly clear, I fall into the "free software" camp. I will be putting that aside for the purposes of this post.

"Open source" means something specific. There's a set of criteria defined by the Debian project Open Source Initiative for what constitutes "open source". It doesn't just mean that the source code is available on the internet.

I wrote a post previously about what free software actually means concretely, and since open source is just a marketing term for free software, the same basic criteria apply.

Here's the short version: something is open source if you can get the source code licensed under an open source license. Check out the full Open Source Definition to see what exactly "open source" means.

However, people tend to use the phrase "open source" to describe any software which has available source code, regardless of the license.

Let me give you an example.

There's a service called Forward Email which claims to be "100% open-source". Look, it says so right there:

However, when you look at the code itself, you can see that it's licensed under the MariaDB Business Source License, which says in the text of the license itself:

The Business Source License (this document, or the "License") is not an Open Source license.

The BSL is interesting because it specifies that at some point in the future (in the case of Forward Email, in 2025), the software will be released under an open source license. But BSL-licensed code should not be called "open source".

Here's another example: Wickr promotes itself as "implement[ing] open source crypto" and claims, "Our crypto library is open source for review and audit purposes". But "source available for review and audit purposes" is not what "open source" means. The Wickr Public Review License explicitly disallows "Commercial Use" (which includes non-commercial use), so you're not allowed to use this code to do things. (You're only allowed to analyze it to ensure that Wickr is using it properly.)

Stop calling things "open source" when they're not open source.