> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sandmark.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Overview

> Sandmark Volatility API

Volatility data

# The vol surface, as a clean timeseries.

Constant-maturity implied volatility at every tenor and delta, alongside realised volatility over matching
lookbacks, for BTC, ETH and other crypto underlyings on Deribit, OKX, Binance and Bybit. The same data behind
Sandmark's own analytics, delivered as JSON over a simple REST API.

[Make your first request](https://docs.sandmark.com/quickstart.md)
[Browse the reference](https://docs.sandmark.com/api-reference/list-assets.md)

## What you get

> [card] [Implied volatility](https://docs.sandmark.com/concepts/implied-volatility.md)
>
> Continuous IV for 9 tenors from 1 day to 1 year and 10 delta points per side. Interpolated in total
> variance, so the series never jumps when an expiry rolls off.

> [card] [Realised volatility](https://docs.sandmark.com/concepts/realized-volatility.md)
>
> Annualised RV of the underlying index over 9 rolling lookbacks, from 1 to 365 days. Line it up against
> IV of the same horizon to read the variance premium.

> [card] [Reference data](https://docs.sandmark.com/api-reference/list-expiries.md)
>
> The assets, sampling frequencies and listed expiries you can query, so your code never has to hard-code
> an identifier.

> [card] [History window](https://docs.sandmark.com/concepts/history-window.md)
>
> Up to three years of hourly history, depending on your billing plan.

> [card] [Backtesting add-on](https://docs.sandmark.com/backtesting/overview.md)
>
> Run options strategies over history with one request: equity curve, every trade and full statistics,
> as JSON, an HTML report or Excel.

## Conventions

These hold for every endpoint. They're worth reading once before you write any code.

> [accordion] Volatility is decimal, not percent
>
> `0.37` means 37%. Multiply by 100 to get the vol points shown on trading screens.

> [accordion] Rows come back newest first
>
> Timeseries rows are ordered by `DATETIME`, newest first. `limit` therefore keeps the most recent rows in
> your range. See [Paging through history](https://docs.sandmark.com/guides/paging.md) to walk further back.

> [accordion] Timestamps are UTC
>
> Every `DATETIME` is the bar close in UTC, ISO 8601 with a `Z` suffix. Query parameters accept any ISO
> 8601 timestamp; one without an offset is read as UTC.

> [accordion] Implied vol is mark vol
>
> IV is read from the `IV_MARK` surface unless you ask for another one with `iv_source_col`. Keep one
> surface for a whole analysis: the two published surfaces differ slightly on every point.

> [accordion] Missing bars are omitted, never filled
>
> If no observation exists for an hour, there is no row for it. Nothing is carried forward or interpolated
> across time.

## Base URL

```text theme={null}
https://api.sandmark.com/volatility
```

Every request needs your API key in the `X-API-Key` header. See [Authentication](https://docs.sandmark.com/authentication.md).


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