Building Sparrow — notes from writing a small Proof-of-Work blockchain in 2026

I built a small Proof-of-Work cryptocurrency called Sparrow (SPW) as a long-running side project. CPU-mineable (RandomX), Bitcoin-style UTXO ledger, optional stealth addresses, no pre-mine, no VC, no governance token. Mainnet has been running since April 2026. This post is about the design choices and what I'd do differently. Why bother building another chain? Most of what gets called a "blockchain project" in 2025–2026 is one of three things: A high-FDV token launch with a smal...