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IV surface (strike × expiry)
The fitted implied-vol surface out to 180 days. z_grid[i][j] is the vol in percent at tenor y_grid[i] (days, ascending) and strike x_grid[j]. Cells are null where the expiry never traded that far out; nothing is extrapolated to fill them. expiry_forwards gives each row’s forward and how it was found, the smile method and fit error, the raw SVI parameters svi where it fitted, its years to expiry t, the log-moneyness span of its quotes k_range, its quoted ATM and wing vols (market) and its quote count. long_expiries carries the same for expiries past 180 days, which are fitted but not drawn on the grid. delta_surface is the same surface by delta. Calendar arbitrage is removed on the grid. How every step works, and what is checked, is on Vol surface methodology.

See also

Vol surface methodology

IV suite

Authorizations

X-API-Key
string
header
required

Your BackQuant API key (same key as v1)

Headers

X-API-Key
string | null

Query Parameters

symbol
enum<string>
default:BTCUSDT

Trading symbol: BTCUSDT, ETHUSDT, SOLUSDT, or HYPEUSDT.

Available options:
BTCUSDT,
ETHUSDT,
SOLUSDT,
HYPEUSDT
as_of
string | null

ISO-8601 instant to answer as of, e.g. 2026-08-20T14:30:00Z. Omit for the current value. Resolves to the nearest chain snapshot AT OR BEFORE the requested time (never after, which would be look-ahead bias); the snapshot actually used and the lag are reported in meta.extra.as_of. Under positioning=flow the dealer flow map is rebuilt from the tape as it stood at that instant, so a given timestamp always returns the same numbers. Bounded by your plan's history window.

Response

Successful Response