The most boring tech imaginable would be a file. Perhaps containing JSON or similar structured data that can be handled using commonly available libraries. Which is exactly what they used for a long time.
I've done something similar before and it saved countless hours wasted on configuring databases, writing queries, fighting impedance mismatches. Postgres brings a lot of work. With a file you just need a couple of lines to write your memory out to a file and a couple more to read it back. Simple and effective.
Until it stops scaling, but at that point you've established that your business is successful enough that it warrants the effort of doing something shiny. Postgres has a place in this world, but no need to put the cart before the horse.
I've done something similar before and it saved countless hours wasted on configuring databases, writing queries, fighting impedance mismatches. Postgres brings a lot of work. With a file you just need a couple of lines to write your memory out to a file and a couple more to read it back. Simple and effective.
Until it stops scaling, but at that point you've established that your business is successful enough that it warrants the effort of doing something shiny. Postgres has a place in this world, but no need to put the cart before the horse.