I sell one thing: a live data stream. Everything that has already finished is free, forever, and that free archive is the evidence the paid stream is measured honestly.
Last week I added a third thing between them — a public page showing today's numbers, deliberately late. It sounds like a small feature. It is actually the most dangerous kind of code in the codebase, because it reads the paid file and publishes part of it, and every bug in it is a bug that gives away the product.
Here is what I got right, what I got wrong, and the two bugs that only showed up in production.
The line: give away timeliness, not a new category
The temptation with a "free tier" is to publish a crippled version of everything. That is hard to explain and harder to defend, because every field becomes a negotiation.
