Data, calculation, and AI that cites.
Most property tools ask you to trust a number. Ours are built so that you never have to: each figure is either a record with a source or the output of a calculation you can inspect. AI sits on top to explain, and it's held to the same rule.
Five stages, each one visible.
In Viiyoo you watch every step run, and you can retry or inspect any of them. Nothing happens in a black box.
One property, one record
An address is matched to a single canonical property, with the candidates shown when it's ambiguous.
Facts with provenance
Every fact is stored as an observation: what it says, which source said it, and when.
Deterministic engine
Comparables, valuation, stamp duty, yields and stress tests run in tested code with exact decimal money.
AI behind a gate
The model writes from an evidence pack. Uncited or unsupported claims fail the gate and are not shown.
Reports and packs
PDF reports, committee packs and Excel workbooks, with the sources carried through.
Every sentence has to earn its place.
When Viiyoo writes a narrative, each claim must carry a token pointing to a source record or a calculation. Before anything reaches you, we check that every token exists, that it's allowed for that claim, and that quoted text really appears in the document it cites.
- Source tokens point to a specific record, such as a sale, a certificate or a planning dataset.
- Calculation tokens point to a figure produced by the engine, never by the model.
- Every AI interaction is logged with its inputs and outcome, for audit.
The flat is in Flood Zone 1, the lowest category of river and sea flood risk 4, and there are no active flood warnings within 5 km 5.
It lies inside a conservation area 7, so changes to windows and frontage may need consent. Local private renting is above the borough average 9, which supports letting demand.
At the estimated value, the gross yield is 4.8% calc.
Illustrative example.
Engineered for serious work.
Canonical property record
Sales, certificates, listings, planning and documents all attach to one property identity, so nothing is counted twice.
Append-only history
Valuations, comparable sets and analyses are never overwritten. A revision creates a new version, so you can see what changed.
Visible, scheduled workflows
Multi-step jobs run as persisted steps you can watch, resume or retry, and scouts and mandate watches run on schedules you set.
Exact financial maths
Money is calculated with decimal types, dated tax schedules and published methodology versions.
Organisation-level privacy
Your portfolios, documents and notes are scoped to your organisation and never feed anyone else's results.
Built for agents
An MCP server with 29 tools and a versioned REST API. Agents quote Viiyoo's figures and every number in their drafts is checked.
Want the technical detail?
We're happy to walk technical and risk teams through our methodology, data handling and architecture.