Implied volatility surface

Type a ticker. You get the whole surface as a 3D map you can turn.

• Only out-of-the-money contracts are priced — puts below spot, calls at spot and above.
• Moneyness is capped to 0.75–1.25. Wider than that, the far wings set the height scale and the smile flattens into a plate.
• Every discarded contract is counted under the map, with the reason.
• Indices need no caret: SPX, XSP, NDX, VIX.

Underpriced options

Which contracts trade below the rest of their own chain.

• Two passes: a price bound that holds without a model, then a dip against the neighbouring strikes.
• The usual answer is "none". That is a result, not a failure.