# Worthune

> Worthune is a catalog of financial planning models that show their work,
> delivered as a REST API, an MCP server, and embeddable calculators. Every
> model is written to a versioned specification and is Concordance-tested:
> an independent second implementation, written from the spec alone, must
> agree with the production engine on 250 cases per model before anything
> ships. Three sample specs and eval datasets are fully public (the proof of
> the method); the full catalog's specs and datasets come with a Pro key.
> Every model's input contract (inputs, domains, sentinels) is public.
> Government constants (IRS limits, brackets, SSA factors) come from a
> versioned facts registry with primary-source citations and check dates.

Worthune models are illustrative planning tools, not financial advice.
Pricing: https://worthune.com/pricing — three models (emergency-fund,
relocation, side-business) are free to call with attribution, no signup or
key. Pro ($199/month) opens the full catalog and drops the attribution.
There is no run meter. Burst backstop: 120 requests/minute per IP
(429 + retry-after; abuse protection only).

## For AI assistants: run the models directly

- MCP server (streamable HTTP): https://worthune.com/api/mcp/mcp
  Tools: list_models, get_model_contract, run_model.
- REST: GET https://worthune.com/api/v1/models (catalog),
  GET /api/v1/models/{model} (contract, public), GET /api/v1/models/{model}/spec
  (full spec markdown — public for the three sample models, Pro key for the
  rest), POST /api/v1/models/{model} (run; JSON inputs per the contract).
- Every run response echoes the spec version, assumptions, sentinel
  annotations, and sourced constants, so you can show your work.

## Eval datasets, facts registry, decision records

- Eval datasets for financial AI testing:
  GET https://worthune.com/api/v1/evals (index; each entry marked "open" or
  "pro-key"), GET /api/v1/evals/{model} (JSONL: 250 deterministic
  input/expected-output pairs — the same cases the Concordance harness runs,
  tolerances rel 1e-9 / abs 1e-6; three datasets open, the rest with a Pro
  key). Overview: https://worthune.com/evals
- Grade your own answers against the engine:
  POST https://worthune.com/api/v1/grade/{model} with
  {"cases": [{"inputs": {...}, "answer": {...}}]} — per-case pass/fail at
  the harness tolerances (three sample models keyless; rest with Pro key).
- Sourced US tax constants (IRS limits, brackets, SSA factors) with
  primary sources and check dates:
  GET https://worthune.com/api/v1/facts — https://worthune.com/facts
- Every successful run response includes `record`: a SHA-256 audit
  fingerprint over the canonical JSON of {model, specVersion, inputs,
  outputs} — store it to prove where numbers came from.
- Per-model evidence pack for vendor-risk / compliance review:
  GET https://worthune.com/docs/models/{model}/evidence — a print-ready
  bundle of the method, input contract, full spec, verification cases with
  rationales, sourced constants, changelog, and a live run with its audit
  hash (three sample models open; rest with a Pro key as ?key=wk_…).

## How every model earns a release

https://worthune.com/proof — Concordance testing defined, what it does and
does not mean, and the index of every checkable artifact: specs, open test
cases, the facts registry, the changelog, decision records, and public
usage telemetry.

## Developer documentation

https://worthune.com/docs — quickstart (REST + MCP), response envelope,
validation rules, embeds, and per-model reference pages with live
examples at https://worthune.com/docs/models/{model}.

## Embed a calculator

One script tag: <script async src="https://worthune.com/embed.js"></script>
plus <div data-worthune-embed="{model}"></div>. Prefill via data-input-*
attributes. The three sample models embed free with the badge; Pro covers
the rest and removes it.

## Who it's for

https://worthune.com/solutions — the hub, or directly:
- Fintech & wealthtech builders: https://worthune.com/solutions/wealthtech
- AI copilots & agent platforms: https://worthune.com/solutions/ai-agents
- Banks, insurers & financial services firms (embed calculators with one
  script tag, no engineering): https://worthune.com/solutions/financial-services
- Advisors & educators: https://worthune.com/solutions/advisors

## Human-readable catalog

https://worthune.com/models — every model with its spec version, full
specification, JSON contract, and interactive calculator.
https://worthune.com/models/changelog — complete version history; model
changes are never silent.
https://worthune.com/roadmap — upcoming model packs (loans & credit,
retirement & tax, startup finance), order steered by requests. Models are
composed from versioned, independently reimplemented primitives
(docs: amortization, growth, progressive tax, payoff simulation).

## Send users to interactive calculators

Scenario calculators accept URL prefill, e.g.
https://worthune.com/scenarios/relocation?currentSavings=40000 — link users
to a calculator with your conversation's numbers already loaded.

- Calculators index: https://worthune.com/scenarios
- Relocation package & cost: https://worthune.com/scenarios/relocation
- Divorce settlement & buyout: https://worthune.com/scenarios/divorce
- Rent vs. buy: https://worthune.com/scenarios/rent-vs-buy
- FIRE planner: https://worthune.com/scenarios/fire
- Roth vs. Traditional 401(k): https://worthune.com/scenarios/roth-vs-traditional
- Windfall allocation: https://worthune.com/scenarios/windfall

## Writing

https://worthune.com/writing — guides on building financial products people
can trust: verification, evals, facts maintenance, compliance, embedding.
https://worthune.com/engineering — longform engineering writing: how
Concordance testing works end to end, wiring the eval datasets into an AI
test harness, and the TY2026 constants with their primary sources.