Real estate

Mastone

From spreadsheet to a full real-estate platform with WWS scoring and an investor portal.

Netherlands · Custom platform Visit website

Mastone real-estate platform built by TopDevs

About Mastone

Mastone is a real-estate firm in Cuijk that buys and sells property directly across the Netherlands, without brokers or brokerage commissions. Through its purchasing arm Mastone Capital, it runs a full-service approach that covers acquisition, renovation, management, rental and uitponden (selling off a portfolio unit by unit). The work leans on a fixed network of appraisers, notaries, contractors and property managers. Valuing homes fast and presenting them well to investors is the daily job, and that job used to live in spreadsheets.

The challenge

Mastone scored homes for the new WWS points system in spreadsheets, with more than 100 conditions to track per property. One slip in a formula could push a home into the wrong category, and every valuation took time the team did not have. On top of that, there were no professional brochures to send investors, so opportunities went out by hand over email, one message at a time. And because the portfolio sat across scattered Excel files, nobody had a single view of what Mastone owned and where it stood. They needed one platform: an admin side for the team and a portal for investors, with the full WWS calculation built in.

The analysis

The WWS (Woningwaarderingsstelsel, the Dutch points system that sets a rental home's legal maximum rent) contains more than 100 conditions that together decide which category a home falls into. That makes manual calculation in spreadsheets error-prone and slow.

We mapped the full calculation logic: from surface-area sums and energy labels to location factors and WOZ values. Every condition has its own weighting and exceptions, which is exactly where a spreadsheet starts to crack.

Beyond the calculations we looked at the way of working. Brochures were shared by hand over email, investors had no portal of their own, and overview was missing because everything lived in separate Excel files.

The conclusion was clear. Mastone needed not just a calculator, but a full platform with user management, brochure generation and an investor portal on top of a single real-estate data model.

What we built

WWS points-calculation engine

The core of the platform: a custom module that runs the full WWS points system in one place. It takes the property data and works through all 100+ conditions to land a home in the right rent category, no spreadsheet required.

Models every WWS condition with its own weighting and exceptions, so the score holds up where a spreadsheet would slip.
Pulls together the inputs that drive the points: surface-area sums, energy labels, location factors and WOZ values.
Turns a calculation that took hours of careful spreadsheet work into a result in seconds.

Rent and yield automation

On top of the points score, the platform works out the numbers an investor actually asks for. It calculates the legal maximum rent a home may charge and the gross initial yield (the BAR, rent against purchase price), automatically, the moment the property data is in.

Automatic calculation of the maximum rent that follows from the WWS category.
Gross initial yield (BAR) worked out from rent against purchase price, so the investment case is clear at a glance.
The figures update straight from the property data, no separate sheet to maintain.

Online brochure generator and shareable access

Instead of mailing documents by hand, Mastone now generates a professional online brochure per property and shares it through a link. It fits the firm's direct, broker-free way of dealing with investors.

Online brochure generator with a professional look, built from the property's own data.
Account management with login and shareable links, so a brochure goes straight to the right investor.
Sharing happens in a few clicks instead of a stream of one-off emails.

Admin and investor portal on a real-estate data model

One platform with two sides: an admin environment where the Mastone team manages the portfolio, and an investor portal where external investors get their own access and overviews. Both run on a database built for complex real-estate data.

Admin environment for portfolio management, replacing the scattered Excel files with one overview.
Investor portal with its own access and overviews for external investors.
Database architecture built to hold complex real-estate data and tie the whole platform together.