Financial planning & wealthtech infrastructure
A financial planning API, not just calculators
A financial planning API goes beyond single calculators: it takes a household — members, accounts by tax wrapper, incomes, expenses — and computes the coordinated picture. Worthune's household engine stores that household as one versioned document and returns a deterministic year-by-year projection, a seeded longevity-aware Monte Carlo, and 7 strategies that answer together: withdrawal sequencing, Social Security timing, Roth ladders against IRMAA cliffs, pension elections, and more — each with a computed dollar delta and every alternative shown.
What to look for — whoever you choose
A household model, not just endpoints
Planning is coordination across accounts. If the API only answers one question at a time, the hard math — which account to draw first, when to convert, when to claim — remains yours to build.
Reproducible simulation
A Monte Carlo that can't reproduce its own bands can't be audited. Look for seeded simulation and stated assumptions — and for who supplies the return assumptions, because that answer determines who carries the market view.
Alternatives, not verdicts
A planning engine that returns only a winner is making a recommendation. One that returns every alternative with computed deltas leaves the advice — and the liability posture — where it belongs.
How Worthune answers it
One document, three computations
POST the household, then project (deterministic + Monte Carlo), decide (the strategies), and monitor (signed webhooks, including drift when a stored plan's numbers move).
→ see the engine wholeNo house view
Return and inflation assumptions are yours to supply; until then results run on labeled illustrative defaults and say so on every surface.
→ read the house rulesSee a full plan computed live
The demo runs the real engines end to end on a labeled fictional household — projection, bands, and the decisions on the table.
→ open the demoWhere this fits: everything above is one platform — calculators & models, planning software, and unified household management, on the same verified engines and one API. How the numbers are made is public: the methodology.
Common questions
Can I build planning software without building the engine?
Yes — that is the product. The household engine handles the projection, the longevity-aware Monte Carlo, and 7 coordination strategies; you build the experience on top, over REST, MCP, or the React component kit.
Whose market assumptions does the engine use?
Yours. The engine never supplies a market opinion — return and inflation assumptions are the caller's to set, and until they are, results run on labeled illustrative defaults that say so wherever they appear.
Is the Monte Carlo reproducible?
Yes. Simulations are seeded, so the same inputs produce the same bands every time — which is what makes a simulated result auditable rather than an anecdote.
Can the planning surfaces run under our brand?
Yes — white-label tenant configuration carries your brand, an accessibility-validated theme, and your appended disclosures, with embeds bound to your domains by short-lived signed tokens.
Talk to us