How to Detect Stellar Deposits Without Running a Horizon Node

A custodial Stellar product, anchor service, or multi-chain payments backend has the same data problem on Stellar that every other chain custodian has. The product needs to detect inbound deposits and outbound withdrawals against a corpus of user-facing Stellar addresses, attribute every event to the right account, decode native XLM and issued-asset payments alike, and stay in sync with the chain without operating stellar-core plus Horizon plus Postgres. This article walks through the data layer Stellar custodians use on B