> ## Documentation Index > Fetch the complete documentation index at: https://docs.backquant.com/llms.txt > Use this file to discover all available pages before exploring further. # Constant-maturity vol > ATM vol, 25- and 10-delta risk reversals and butterflies at fixed tenors from 7 days to 1 year, with static-arbitrage checks. The vol desk's view of the surface: ATM, the 25- and 10-delta call and put vols, risk reversals and butterflies at 7, 14, 30, 60, 90, 120, 180, 270 and 365 days. Fixed tenors compare cleanly across time and across coins, where listed expiries roll. Each expiry's ATM and wings are read off its quoted smile at Black-76 forward-delta strikes; each tenor interpolates total variance linearly in time between the two fitted expiries around it. Nothing is extrapolated: a tenor or a wing the quotes do not reach is null. Every response also carries the static-arbitrage checks on each fitted smile (`butterfly_free`, `calendar_free`, `min_density_g`) and a summary in `arbitrage`. The full method is on [Vol surface methodology](/concepts/vol-surface). ```json theme={null} { "tenors": [ { "tenor_days": 30, "atm_iv": 35.53, "iv_25c": 35.35, "iv_25p": 37.59, "iv_10c": 36.23, "iv_10p": 41.72, "rr_25": -2.24, "bf_25": 0.94, "rr_10": -5.49, "bf_10": 3.45, "bracket_dte": [26.15, 47.15] } ], "arbitrage": { "butterfly_free": true, "calendar_free": true, "violations": [] } } ``` Vols in percent. `rr` is call minus put, so it is negative when puts are bid; [`/v2/options/iv/skew`](/api/v2/options/iv/skew) reports put minus call. Current values only, refreshed with the surface about every 30 seconds. ## See also ## OpenAPI ````yaml GET /options/iv/constant-maturity openapi: 3.1.0 info: title: BackQuant API v2 description: >- # BackQuant API v2 Options + gamma-exposure focused public API. Built on the same data the BackQuant Pro Terminal renders - pre-computed every 30s, served from cache. ## What's in v2 * **Discovery**: `/v2/symbols` (universe + per-symbol freshness + supported endpoint list), `/v2/expiries` (active expiry tokens with DTE), `/v2/status` (per-symbol-per-category health with thresholds + overall classification). * **GEX**: composable levels (HVL / call wall / put support / max-pain / expected move / gamma-flip zones), strike profile with typed expiry filter, expiry profile, strike × expiry heatmap with downsampling, greek time-heatmap with DTE/OI/IV filters, history (cursor-paginated), Postgres-backed stress history, **per-expiry max-pain with pain curve**. * **Options**: filtered options chain with two-layer projection (top-level `?fields=` and per-contract `?include=oi,iv,greeks,bid_ask,volume,gex`) plus moneyness filter (`?moneyness_min=0.9&moneyness_max=1.1`), expiry summary table, full IV suite (surface / term structure / 25Δ-10Δ skew / curves / **single-expiry smile** / IV-RV history / VRP), expected move, **Breeden-Litzenberger probability density and surface**, typed greek profiles (delta / theta / vanna / charm / vega), strike × time charm/vega surfaces, strike × expiry 3D greek surface, OI by expiry + history, put/call ratio (intraday or daily), 0DTE & weekly premium tide, dated-futures term structure. * **Liquidation**: heatmap + leverage-tiered distribution. * **Multi**: `/v2/multi/gex/levels` - bundled multi-symbol read across the universe in one round-trip, with the same `?include=` model as the single-symbol endpoint. ## Authentication Every v2 route (except `/v2/openapi.json`, `/v2/docs`, `/v2/redoc`, and `/v2/health`) requires the `X-API-Key` header. ``` X-API-Key: bq_live_your_api_key_here ``` **Get your API key at [backquant.com/api-access](https://backquant.com/api-access).** The same key works across v1 and v2 - if you already have a v1 key, no re-issuance is needed. ## Rate limits Two budgets, both derived from your subscription tier: a **monthly request allowance** per account, and a **per-minute burst** per key. Size your integration against the monthly figure - sustained polling at the burst rate exhausts the month early. | Plan | Monthly allowance | Burst | Sustained | |---------------------------|-------------------|----------|-------------| | Starter (Terminal Yearly) | 10,000 req/month | 10/min | ~333/day | | Standard (Crypto API) | 250,000 req/month | 60/min | ~8,300/day | | Pro (Terminal + API) | 1,000,000/month | 120/min | ~33,000/day | | Enterprise | custom | 600/min | custom | Headers `X-RateLimit-Limit / -Remaining / -Reset` (burst) and `X-Quota-Limit / -Used / -Remaining / -Period` (monthly) are included in every response; the rate-limit triple is echoed inside `meta.rate_limit` when populated by middleware. Exceeding either budget returns `429`. The live ladder is served at `GET /v2/meta` under `rate_limits`. ## Response envelope ```json { "success": true, "data": { ... }, "meta": { "version": "2.0", "timestamp": "2026-04-29T12:00:00.000Z", "request_id": "req_…", "symbol": "BTCUSDT", "spot_price": 67213.5, "computed_at": "2026-04-29T11:59:48.000Z", "freshness_seconds": 12.0, "source": ["deribit","bybit","okx","binance","derive","thalex","delta_india","delta","bullish","paradex"], "exchanges_filtered": ["deribit","bybit"] } } ``` ## Errors ```json { "success": false, "error": { "code": "NOT_FOUND", "message": "No data for BTCUSDT" }, "meta": { "version": "2.0", "timestamp": "..." } } ``` | Code | When | |-----------------------|------| | `UNAUTHORIZED` | Missing or invalid API key | | `FORBIDDEN` | Subscription doesn't allow API access | | `NOT_FOUND` | Symbol/expiry/etc. not present in cache | | `VALIDATION_ERROR` | Bad query parameters | | `RATE_LIMIT_EXCEEDED` | Per-tier limit hit | | `UPSTREAM_ERROR` | Cache or DB temporarily unreachable | | `INTERNAL_ERROR` | Anything else | version: '2.13' servers: [] security: [] tags: - name: Meta description: Unauthenticated metadata + endpoint catalog (planning your integration) - name: Discovery description: Symbol catalog, active expiries, and service status - name: GEX description: Gamma exposure analytics - name: Options description: Options chain, IV, greeks, probability, premium tide - name: Liquidation description: Liquidation heatmap and distribution - name: Multi description: Bundled multi-symbol endpoints (single round-trip across the universe) - name: COT description: >- CFTC Commitments of Traders: futures positioning by trader category (public CFTC data) - name: Filings description: >- SEC Form 4 insider trades and 13F holders for MSTR, COIN, HOOD and IBIT (public SEC data) paths: /options/iv/constant-maturity: get: tags: - Options summary: 'Constant-maturity vol: ATM, risk reversals, butterflies' description: >- ATM vol and the 25- and 10-delta wings at fixed tenors (7, 14, 30, 60, 90, 120, 180, 270 and 365 days), from the expiries whose smile fitted on the surface, including the long-dated ones past its grid. Per expiry, ATM is the vol at the forward and each wing the vol at the strike of that delta (Black-76 forward deltas; a put's delta is read on the call-equivalent axis, so the 25-delta put sits at call delta 0.75), read off the expiry's quoted smile with total variance linear in log-moneyness between neighbouring quotes. Each point's total variance is then interpolated linearly in time between the two expiries that bracket the tenor. No extrapolation: a tenor outside the fitted expiries, or a wing beyond the quoted strikes, is null. Conventions, all in vol points: `rr_25` = 25-delta call vol minus 25-delta put vol (negative when puts are bid), `bf_25` = their average minus ATM; the same for 10-delta. Note `/v2/options/iv/skew` reports put minus call. `expiries` gives the same numbers at each fitted expiry's own maturity with its quote count `n_quotes` and static-arbitrage checks; `bracket_dte` names the expiries each tenor sits between. `arbitrage` summarises the checks over every fitted smile: `butterfly_free` (Durrleman's density condition g(k) >= 0 across each expiry's quoted strikes), `calendar_free` (total variance does not fall from one fitted expiry to the next across their common strikes) and any `violations`. Current values, refreshed with the surface every 30 seconds. operationId: get_iv_constant_maturity_options_iv_constant_maturity_get parameters: - name: symbol in: query required: false schema: enum: - BTCUSDT - ETHUSDT - SOLUSDT - HYPEUSDT type: string description: 'Trading symbol: BTCUSDT, ETHUSDT, SOLUSDT, or HYPEUSDT.' default: BTCUSDT title: Symbol description: 'Trading symbol: BTCUSDT, ETHUSDT, SOLUSDT, or HYPEUSDT.' - name: X-API-Key in: header required: false schema: anyOf: - type: string - type: 'null' title: X-Api-Key responses: '200': description: Successful Response content: application/json: schema: {} '401': description: Invalid or missing API key content: application/json: example: success: false error: code: UNAUTHORIZED message: Invalid API key meta: version: '2.0' timestamp: '2026-04-29T12:00:00Z' '404': description: No data available for the requested resource content: application/json: example: success: false error: code: NOT_FOUND message: No data for BTCUSDT meta: version: '2.0' timestamp: '2026-04-29T12:00:00Z' '422': description: Validation error on query parameters content: application/json: example: success: false error: code: VALIDATION_ERROR message: Invalid request parameters details: errors: [] meta: version: '2.0' timestamp: '2026-04-29T12:00:00Z' '429': description: Rate limit exceeded content: application/json: example: success: false error: code: RATE_LIMIT_EXCEEDED message: Rate limit exceeded. Try again later. meta: version: '2.0' timestamp: '2026-04-29T12:00:00Z' security: - ApiKeyAuth: [] components: securitySchemes: ApiKeyAuth: type: apiKey in: header name: X-API-Key description: Your BackQuant API key (same key as v1) ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.