● Finance·fintech
Cost & performance turnaround on an undocumented legacy system
Reverse-engineered a system whose owners had left and whose docs were gone, then stopped the cost leaks and bottlenecks.
−76%
monthly infra cost
3×
response speed
architecture map
legacy restored
● THE CHALLENGE
Why it was hard.
Years of staff turnover left a system nobody fully understood in production. There were no docs, and with no idea what a change might break, both cost and performance were left untouched. The bill grew every month, yet where it leaked was unclear.
Constraints
- Analyze without any downtime
- No docs or owners — reverse engineering was a given
- Cutting cost without root cause risks outages
● OUR APPROACH
What we did.
- Measure & reverse-engineerTrace traffic, billing, and dependencies to rebuild the real structure
- Find bottlenecks & leaksQuantify cost drivers and performance bottlenecks
- Safe improvementNarrow blast radius, resize and rebuild in stages
- Docs & guardrailsLeave an architecture map and cost guardrails to prevent recurrence
● OUTCOME
Outcome.
Reverse engineering redrew the scattered system, clearing the leaks and unblocking bottlenecks. Monthly infrastructure cost fell 76%, from about $1,650 to $400, while response times improved — and we left structure docs the next person can actually read.
● RELATED INSIGHT
The detailed record, from diagnosis through execution.
● STACK
Stack.
AWSCloudWatchCost ExplorerTerraformObservability
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● RELATED SERVICE
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