Foundations / Feasly Calculation Engine & Integrations
Financial capability you can build on.
The Feasly Calculation Engine connects assumptions to cash flow, funding, value and returns. Work through Feasly, or discuss how to embed its methods in your own software.
Discuss engine access
FeaslyCalculation Engine
One calculation foundation. Different ways to work.
Work in Feasly
Feasly workspaceModel, compare & review
Work in ExcelConnected add-in · in testing
Import existing modelsSupported legacy files
Your assumptions
Build with Feasly
Access & deployment in development
Different interfaces. A calculation foundation you can investigate, reconcile and build on.
The financial foundation
Follow the financial relationships.
A delay can change receipts and funding. A lease can change income and value. Trace the relationships through financial methods appropriate to the case.
Make the calculation open to investigation.
We built the calculation foundation first to verify and improve the methods behind your analysis. Investigate how assumptions interact and why results differ. Reconcile a known case and examine the calculation as the methods develop.
Follow a worked exampleWork in Feasly
Use the financial depth in different ways.
Work through Feasly, supported Excel workflows or the optional Analyst. AI proposes supported actions; the Calculation Engine applies financial methods. You control assumptions and retain professional judgment.
Build with Feasly · In development
Build in your own environment.
Discuss engine access, APIs, MCP and private deployment of the engine or full application. Agree the methods, versions and support your integration needs.
Discuss your integrationBuild with financial methods.
Why integrate a calculation engine instead of building the financial model ourselves?
Consider Feasly when your product needs real estate financial calculations and your team wants to build its own interface, reports or AI workflow around them. The integration discussion starts with the methods and outputs you need: project costs and receipts, period cash flow, supported funding, value or returns. You still own the input mapping, validation and application decisions. Establish whether the available Feasly methods fit before comparing the cost of an integration with building and maintaining those methods internally.
What should an API or MCP integration prove?
Start with a known case and expected results. Agree supported inputs and outputs, units, timing conventions, calculation version, error handling and how your system retains a record of each request and result. If AI can propose changes, decide which actions require human review and who controls the assumptions. API and MCP availability, authentication, deployment and support must be agreed for the assignment; a protocol name alone does not establish compatibility.
Is the free feasibility calculator the full Feasly engine offering?
No. The public calculator exposes a defined early-screening calculation. The wider Feasly product connects supported development and income-property modelling with scenarios, source documents and review. Standalone engine access and private deployment are developing offers. A public calculator result demonstrates its stated scope, not the availability of every method through a self-service API.
Can I work with my Feasly projects in ChatGPT?
Bring your Feasly financial work into ChatGPT. Open a saved project, work on a development or investment model, and save scenarios to the same Feasly workspace. Available by invitation during private preview. Feasly has been submitted for review in the ChatGPT directory; public installation is not yet available. A Feasly sign-in is required for saved projects.