Migrating a Legacy Monolith to Microservices Without Disrupting Live Operations
A mid-market logistics technology company
A logistics platform running critical supply chain operations for 40+ enterprise clients needed to migrate an eight-year-old monolith to a microservices architecture — without a single hour of unplanned downtime affecting live shipment tracking.
The Challenge
The migration constraint
The platform's monolithic architecture had accumulated eight years of business logic, and its 40-plus enterprise clients had contractual SLAs requiring 99.9% uptime. A greenfield rewrite was not an option — the migration had to run in parallel with live operations, using a strangler-fig pattern that required engineers who had done exactly this kind of migration before.
The internal team had strong product domain knowledge but limited distributed-systems migration experience. Hiring engineers permanently for a one-time architectural migration — and then carrying them indefinitely — was rejected by the CFO as economically irrational.
At a glance
- 199.9% uptime SLAs with 40+ enterprise clients — non-negotiable
- 2Eight years of accumulated business logic in a single monolith
- 3Strangler-fig pattern required engineers who had done it before
- 4CFO rejected permanent hires for a time-bounded architectural project
The Solution
How HireNXT solved it
HireNXT's matching was scoped to engineers with verified strangler-fig migration experience — specifically, prior engagements involving parallel-running legacy and new services with live traffic routing between them.
Eight engineers were sourced from three staffing partners and evaluated against a technical scenario designed by the client's principal engineer: a simulated service extraction from a representative monolith slice, assessed for approach correctness, observability design, and rollback strategy.
Engagements were structured in two phases: a four-month core migration phase for the eight engineers, with an option to retain a subset for a stabilisation and knowledge-transfer phase — exercised for three engineers who embedded with the internal team through go-live.
A single consolidated dashboard tracked all eight contractors' timesheets, milestone completions, and deliverable sign-offs against the migration project plan.
We couldn't afford a single hour of unplanned downtime, and we couldn't afford to hire eight senior distributed-systems engineers permanently for a migration that had a clear end date. HireNXT solved both problems. We shipped 34 services in nine months with zero SLA breaches.
VP of Engineering
Mid-Market Logistics Technology Company
The Results
What changed
All 34 services were successfully decomposed and deployed over nine months, with zero hours of unplanned downtime affecting live enterprise client operations.
Three engineers from the core team were retained for the stabilisation phase and completed comprehensive knowledge transfer, leaving the internal team fully capable of owning the new architecture.
The migration was completed within the original nine-month budget, with no permanent headcount added — a saving the CFO cited as a key outcome in the post-project review.
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