Replacing a spreadsheet process with a portal in eleven weeks
Marlow onboarded every client through a shared spreadsheet, three email threads and a weekly reconciliation meeting. At 140 clients it broke. We scoped hard, built a portal, and handed it over with tests their engineers trusted.
- Timeline
- 2 weeks discovery, 11 weeks build
- Market
- United Kingdom
- Published
- September 30, 2025
- 4.5 days
- Median onboarding time
- 11 weeks
- Build duration
- 78%
- Test coverage at handover
- 31/week
- Ops hours saved
-63%
The challenge
Client onboarding took twelve days, involved four systems and a manual reconciliation nobody enjoyed. The internal engineering team was fully committed to the core product and could not take it on for at least three quarters.
What we did
Cut the scope in half
Discovery produced a wish list of forty-one features. We shipped seventeen. The other twenty-four went into a backlog, and eighteen months later most remain unbuilt because nobody has needed them.
Foundation sprint first
Repo, CI, preview environments, auth, role model and the core data layer before any feature work. Unglamorous, and the reason the last six weeks moved fast.
Vertical slices, demoed fortnightly
Every two weeks a working slice went to a staging environment their ops team used with real data, which surfaced three wrong assumptions early enough to be cheap.
Handover as a deliverable
Architecture decision records, 78% coverage on business logic, a runbook, and two walkthrough sessions with their engineers before we stepped back.
The result
Median onboarding dropped from twelve days to four and a half. The weekly reconciliation meeting was cancelled. Marlow engineers have since shipped three features to the portal without our involvement, which is the outcome we were aiming for.