Problem
A fintech company processing real-time payments was running on a 12-year-old database. The system was slow and getting slower — processing speed dropped 15% every quarter. They’d maxed out the capacity of their existing setup, and the next step was “hope nothing breaks.”
The bigger problem: the system was so fragile that the team had stopped making improvements. Customer-facing features sat on hold because any change risked breaking the payment system. The CEO described it as “the single biggest constraint on the business.”
Approach
We replaced the old system with a modern one in stages, so the business kept running the entire time. Nothing was shut down, and every step could be reversed if something went wrong.
- Weeks 1-2: Mapped everything the old system did — every process, every connection, every dependency. No surprises later.
- Weeks 3-6: Built the new system alongside the old one. Both ran at the same time, processing the same data, so we could compare results and catch problems early.
- Weeks 7-10: Moved services over one by one. Each piece was tested independently before we switched it over.
- Weeks 11-12: Final switchover. The old system was kept as a backup for 30 days, then retired.
The entire migration happened without a single minute of downtime.
Results
Processing speed improved by 94%. The system now handles 3.2x more volume than before. But the real win was organizational — the team went from being afraid to touch the system to making improvements every week.
The CEO later said the migration “unblocked two years of product plans in three months.”