PayZoll.

Cross-border payroll and treasury for teams whose members all hold different assets. I was sole technical owner of the payment infrastructure on a two-person founding team. The Stellar Disbursement Platform went from single-tenant to a multi-tenant distributed system running batch payroll for many organizations at once, with signing keys derived in AWS KMS instead of stored as raw tokens and payroll records encrypted at rest with pgcrypto. The interesting constraint was throughput: SDP was capped at eight channel accounts, roughly two transactions per second. Soroban's authorization-tree model let a single channel account fan out into many parallel contract calls, which took it to about 200.