Sqlite is in the public domain and, like redis, has various apis for writing your own extensions. Some of those extensions are free, some are proprietary (thinking of sqlite encryption extension, although there are free alternatives).

There's nothing new about this. Postgres has apis for writing foreign data wrappers, MySQL has pluggable storage engines, etc etc.

Is antireZ worried about redis' reputation after the hn license drama? Is he just waxing philosophical? I kept waiting for the post to go somewhere.

Redis is awesome. antireZ is doing great work. Its a bummer he felt compelled in some way to write this.