Policy Engine
Version, test, and deploy lending policy with the rigour of software.
The Policy Engine is the rulebook behind every Mast decision. Affordability, credit, KYC, fraud, and compliance rules are all expressed as versioned code, tested against real cases, and deployed with the same review and rollback controls your engineering team already trusts.
What it does.
Policy-as-code
Rules expressed in a readable, testable format. Diff, review, and merge like any other engineering artefact.
Champion and challenger
Run new policy against live traffic in shadow mode, compare outcomes, then promote when you are ready.
Full test coverage
Regression suites of historical cases so you can prove a policy change does what you expect before it goes live.
Explainable decisions
Every decision links back to the exact rule that produced it. No black boxes, no reconstructed reasoning.
Role-based change control
Product, credit, and compliance teams propose changes; sign-off routes through the right approvers before publish.
One rulebook, every channel
The same policy governs calculators, broker journeys, direct journeys, retentions and contract variations.
Where it fits.
Affordability, stress test, and ICR rules that change with market conditions
Credit policy that varies by product, channel, and risk appetite
KYC, KYB, and fraud rules with clean override paths
Compliance guardrails around vulnerability, suitability, and consumer duty
Plays well with the stack.
Mast Origin journeys and case data
Bureaus, valuations, and fraud providers as rule inputs
Version control and CI so policy changes flow through your existing pipelines
What good looks like.
Move a stress rate or an LTV cap in minutes, with a full test and audit trail.
One rulebook for every surface, versioned and enforced.
Every decision reproducible, every rule change attributable.
See Policy Engine in action
Walk through your workflow with the team and see how it fits.
Get in touch