| Suppose you have an open source or hobby project. The Free Edition has limitations that impact how you would write code -- it supports only the "peer" API and not the "client" API, and is restricted in terms of backend storage choices and number of peers. So while it's very likely true there's perfect API compatibility when you want to step up to a paid edition, it makes you design to the artificial limitations they've used to set apart "free" from "paid". Indeed, it's also not the recommended way to learn. The Datomic team says: "If you are trying Datomic for the first time, we recommend that you begin with a client library." In other words, the Free Edition doesn't include the client library that they recommend you try first. If you step up to the Starter Edition you have full functionality and free updates but only for the first year. Beyond that, you start paying. Either you run in Cloud (as low as $1/day) or you purchase the on-prem Pro Edition ($5000/year). Don't get me wrong. Cognitect has the right to charge whatever they like, and bundle features however they like. It's their intellectual property and they made the investment to create it. But if you're building a hobby project then even $1/day may be more than you want to spend, and/or more than you want to impose on outside contributors to your codebase. |
Even if this drives you to the $1/day edition, that should cover a lot of small projects. Especially as you don't have to keep it running 24/7 during development.