Derivatives pricing & risk · live web app · open methodology

Price an option. See how the number was made.

QuantFlex is a pricing workbench built by hand — Monte Carlo, finite-difference PDE and automatic-differentiation Greeks, with no pricing library underneath. Every result carries the exact inputs, seed and engine version that produced it, so you can check it, change one thing, and run it again.

New to options? Start with a guided calculation and plain-language explanations. Already pricing derivatives? Go straight to the full parameter set, the method notes and the export.

Both buttons open the live app at app.quantflex.dev. Learn currently lands on the pricing workbench with its worked examples; Research lands on the methodology notes. Dedicated /learn and /research entry pages are being built and will be linked here once they are deployed and verified — not before.

Two ways in, one set of numbers

Different starting points, the same transparent calculations underneath. Nothing is simplified away for newcomers — it is explained instead.

Learn

New to options? Start here.

A first calculation in a few minutes, with every term explained in ordinary words and every assumption stated where you can see it.

  1. Pick a worked example. An at-the-money call, a protective put, a short-dated high-vol case — each one preset and priced.
  2. Read what the price means. What the option gives you, what you pay, and what the model assumes to get there.
  3. Change one input. Move the volatility or the expiry and watch the price and the Greeks respond. The sliders below do exactly this, right on this page.
  4. Keep the result. Export CSV or JSON, or copy a link that reopens the same calculation with the same inputs.
Research

Already pricing derivatives?

Full parameter control, method notes, and results you can reproduce bit-for-bit from the export.

  • Methods — closed form, Monte Carlo with standard error and 95% CI, Crank–Nicolson PDE, Longstaff–Schwartz.
  • Models & payoffs — GBM, Merton jump-diffusion, Heston; European and American exercise; Asian, barrier, lookback, basket and spread payoffs.
  • Greeks with the check shown — AAD tape against finite differences, per-Greek tolerance, and the disagreement flagged if it happens.
  • Reproducibility — inputs, seed, engine version and request hash travel with every result; CSV/JSON export; copyable links.
  • API — the same engine over HTTP, documented with OpenAPI.

Try it — a first calculation, in your browser

This is the closed-form Black–Scholes price of a European option. Move anything and the price, the Greeks and the payoff diagram recompute instantly. Nothing is sent anywhere; it runs here.

Price
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What am I looking at? Plain-language notes
Price
What the model says the option is worth today, per unit of the underlying, in the same currency as spot and strike.
Spot / Strike
Spot is the price of the underlying asset now. Strike is the price the option lets you buy (call) or sell (put) at.
Volatility
How much the underlying is assumed to move, as an annualised percentage. Higher volatility makes both calls and puts worth more.
Delta
How much the option price changes if spot moves by $1.
Gamma
How much delta itself changes if spot moves by $1 — the curvature.
Vega
How much the price changes if volatility moves by one percentage point.
Theta
How much value the option loses per calendar day, all else equal.
Rho
How much the price changes if the risk-free rate moves by one percentage point.

Assumptions on this page: the underlying follows geometric Brownian motion with constant volatility and rates, there are no transaction costs, and the option can only be exercised at expiry (European). Those are the Black–Scholes assumptions; they are convenient, not true. The full app lets you relax them — jump-diffusion, stochastic volatility, early exercise — and see how much the price moves.

Engine snapshot — real output, recorded, not live

The tables below are genuine output from the pricing engine, committed to this site as a fixed snapshot. They are not market data and they do not update on a schedule: the engine is deterministic under fixed seeds, so these figures change only when the engine changes.

Source
Engine price() / greeks() calls, run at build time into data/demo.json
Recorded
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Engine version
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Parameters
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What works today, and what is coming

An honest inventory. Everything on the left is in the live app now. Everything on the right is planned, not built — nothing there is a button, and no dates are promised.

In the app today

  • Pricing workbench — closed form, Monte Carlo, PDE and Longstaff–Schwartz across GBM, Merton and Heston, with worked-example presets. Open
  • Greeks panel — AAD values with the finite-difference cross-check and per-Greek tolerance displayed.
  • Exports & links — CSV and JSON download of a result with its inputs, seed, engine version and request hash; copyable links that reopen the same calculation.
  • Methodology & roadmap — how each method works and what is anchored against what. Methodology · Roadmap
  • Market Intel & Daily Rundown — a daily digest of public finance headlines and a daily analysis narrative, with an optional weekly email. Intel · Rundown
  • Planner — savings and allocation planning with clearly flagged estimates. Planner
  • HTTP API — /price, /greeks and a spot × vol grid, documented with OpenAPI. API docs
  • This page's market feed — public headlines collected once a day, below.

Coming soon — not yet built

  • Coming soon Dedicated Learn and Research entry pages in the app. Until they are deployed, the buttons on this page use the existing pricing and methodology routes.
  • Coming soon Excel workbook download with Inputs, Results and Provenance sheets. Today's CSV/JSON export is the baseline; a native workbook is a separate deliverable.
  • Coming soon Live Excel refresh — a read-only data connection from a supported Excel to the API. Distinct from a download, and not started.
  • Coming soon Platform- and firm-specific code export — reproducible research code first, adapters for named platforms after; no certification claimed.
  • Coming soon Daily strategy simulations — paper-only, fixed seeds, declared costs, with failed and skipped runs shown alongside results.
  • Coming soon Strategy brief assistant — turns a plain-language bot idea into a typed, editable specification with a validator. No live orders, no broker credentials.
  • Coming soon Portfolios & risk — VaR/CVaR with component decomposition.

Nothing in this column is interactive on purpose. If a feature is not here yet, this site will not pretend it is.

Daily market feed

A scheduled job collects headlines from public finance syndication feeds once a day and commits them here. Third-party links, filtered by category — not analysis, not advice. The app's Daily Rundown is where the weekly email digest lives.

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