> ## 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.

# Health check

> Lightweight liveness/readiness probe for external monitors. Reports overall status plus per-subsystem (redis, db) flags. Auth-free — uses the same `check_connection_health()` Fly.io's load balancer hits at `/health`. Rate limit: **60/minute per IP**.

Status values: `ok` (all subsystems healthy), `degraded` (one subsystem failing), `unhealthy` (cache + DB both unreachable).

Auth-free liveness probe for monitors. Returns subsystem status (Redis + Postgres).

## See also

<CardGroup cols={2}>
  <Card title="Data freshness" href="/concepts/data-freshness" icon="bookmark" />
</CardGroup>


## OpenAPI

````yaml GET /health
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


    Per-key, derived from your subscription tier:


    | Tier        | Limit                |

    |-------------|----------------------|

    | Monthly     | 60 requests/min      |

    | Yearly      | 120 requests/min     |

    | Enterprise  | No limit             |


    Headers `X-RateLimit-Limit / -Remaining / -Reset` are included in every

    response, and the same triple is echoed inside `meta.rate_limit` when

    populated by middleware.


    ## 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"],
        "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: 2.0.0
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)
paths:
  /health:
    get:
      tags:
        - Meta
      summary: v2 health check (no auth)
      description: >-
        Lightweight liveness/readiness probe for external monitors. Reports
        overall status plus per-subsystem (redis, db) flags. Auth-free — uses
        the same `check_connection_health()` Fly.io's load balancer hits at
        `/health`. Rate limit: **60/minute per IP**.


        Status values: `ok` (all subsystems healthy), `degraded` (one subsystem
        failing), `unhealthy` (cache + DB both unreachable).
      operationId: get_health_health_get
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
      security:
        - ApiKeyAuth: []
components:
  securitySchemes:
    ApiKeyAuth:
      type: apiKey
      in: header
      name: X-API-Key
      description: Your BackQuant API key (same key as v1)

````