Bitcoin and Lightning development

Bitcoin development with protocol experience

Bitcoin places different demands on software than ordinary payment systems. Transactions cannot be reversed, keys must be handled with great care, and many users expect to run the software on their own hardware. We have worked with Bitcoin for many years and know the protocol, the libraries, and the surrounding ecosystem.

For Bitmynt, Norway’s oldest bitcoin exchange service, we contributed to a new platform with automated trading. We have also reconstructed historical BTC/NOK prices for 2010–2014, and we maintain Canary, a self-hostable service that monitors wallets with xpubs and descriptors through BDK and Electrum, without ever having access to the funds.

Architecture choices in Bitcoin projects: keys, nodes, and regtest

In Bitcoin, the most important decisions are often made before the first line of code. These are the choices we make in most projects:

• Watch-only wherever possible. Services that monitor, report, or create invoices get only descriptors or xpubs. Signing happens with the user, ideally on a hardware wallet via PSBT.
• A deliberate choice of data source. Your own Bitcoin Core node gives the best privacy and the least trust in others, while an Electrum server is quicker to get started with. We make the choice explicit, and let users of self-hosted software point to their own node.
• Amounts as integer satoshis. Never floating point, and conversion to NOK or other currencies only where the amount is displayed.
• Reorgs taken seriously. The logic must cope with a transaction disappearing from a block, and the number of confirmations is matched to the amount.
• Regtest in the tests. Integration tests run against real nodes on a local regtest network, where we can mine blocks and provoke failures in seconds, before anything is tried on testnet or signet.

Lightning, BTCPay Server, and hardware

We have built a BTCPay Server plugin in C# that receives Lightning payments directly into Bare Bitcoin, and an integration that records donations in WordPress and WooCommerce. We have worked on Lightning wallets based on lnd and Flutter, on Stratum V2 solo mining in Canary Mining, and on Nostr identities derived from passkeys. On the hardware side, we have written a Go library for Satscard and other NFC cards, and an offline, dice-based seed generator for ESP32.