I Built a REST API for Bitcoin Core - Here's what I Learned

I run a Bitcoin full node. When I started building apps against it, I hit the same wall everyone hits: Bitcoin Core's JSON-RPC is designed for node operators, not application developers. The RPC works. It's stable, well-documented, and battle-tested. But if you've ever tried to build a product on top of it, you know the pain points. So I spent a few months wrapping it in a proper REST API, and I learned some things worth sharing. The Problem Nobody Talks About Bitcoin Core's RPC returns fees in BTC/kVB. Every application developer on earth thinks in sat/vB. That's a multiplication, a unit conversion, and a mental model mismatch — on every single call. estimatesmartfee returns one estimate per call. Want fee recommendations for 1, 3, 6, and 144 blocks? That's four RPC round-trips, four response parses, and you still have to write the logic to tell your user "fees are moderate right now, you can wait." getmempoolinfo gives you transaction count and total size. Useful, but what developers