A Power Apps developer in London who did the finance job first.
Castlane replaces the spreadsheets a growing business depends on and only one person understands. One system, built around how the business actually runs, by a management accountant, so you can take on more work without more admin and the numbers come out right.
Malacki Rhooms · Microsoft certified, Power Platform (PL-900, PL-200) · CIMA part-qualified · AAT · Tooting, London
Why a management accountant builds software
Before I built systems I ran the numbers for a growing business: budgets, forecasts, management reports, the bookkeeping underneath them. The reports came out of spreadsheets, and the spreadsheets came out of other spreadsheets. Every month-end was a week of chasing versions, re-keying figures and explaining why two totals that should match did not.
So I replaced them. First with better workbooks, then with applications on the Microsoft 365 the business already paid for. The admin that had needed five people needed one. Invoices went out on time. The owner could see the margin on a job before it was finished rather than months after.
That is the whole of Castlane. I build the system a finance person would build if they could: one that captures the data once, at the point it happens, and gives the office, the owner and the accountant the same numbers. I do not need the process explained in software terms, because I have done the process.
Outside Power Platform I have also delivered an AI-based application for a client as a one-off, which tells you the range; it is not what Castlane sells.
Track record
Systems built for a London tuition group, 2023 to 2025. Anonymised; the business is not named.
300 to 1,000
Tutor recruitment
An application that took the tutor base from 300 to 1,000, with acquisition up 130% in six months.
Counted from the tutor records in the system: tutors onboarded, checked and ready to work, not just registrations.
£150,000 a year
Operations
Two weekend schools run by one administrator instead of five staff, saving £150,000 a year.
Headcount from the payroll before and after; the saving annualised from the salaried roles that came off the cost base.
8 staff, hundreds of clients
CRM and billing
The industry’s standard platform replaced with a Power Apps CRM on Dataverse and a billing-enabled client portal on Power Pages, used by eight staff for several hundred clients and tutors.
User and client counts from the system at handover.
How I work
One person, start to finish
The person you speak to on the call is the person who maps the process, builds the system and trains your team. Nothing is handed to a junior or an offshore team.
Fixed price, agreed scope
You know the cost before the build starts. If I misjudge the time, that is my cost. If you add to the scope, it is quoted separately, so neither of us is surprised.
Your Microsoft 365, your system
Built in your own tenant, documented, and handed over with the solution files. If you want to leave, you can. The systems I built in 2023 to 2025 are still in daily use.
Castlane is based in Tooting, south London. I work on site in London and the south east and remotely for everyone else. How a build runs · Packages and prices