> ## Documentation Index > Fetch the complete documentation index at: https://docs.skylit.ai/llms.txt > Use this file to discover all available pages before exploring further. # List underlyings active on a date > Lists every ticker that traded options on the requested date, ordered by total premium (descending). Useful as a starting point for discovery or for repopulating the universe of tradable tickers. ## OpenAPI ````yaml /flowseeker-openapi.yaml get /v1/underlying openapi: 3.1.0 info: title: Flowseeker — Skylit Public API version: 1.0.0 summary: Real-time and historical options-flow analytics as a public HTTP API. description: > Flowseeker exposes Skylit's real-time options-flow scoring stack — Flow Score, FlowBonus, VWF/SDF/FIR aggregates, sector rotation, and market breadth — as a versioned public HTTP API. Data is sourced from Databento OPRA + ThetaData with sub-second freshness during market hours. **Authentication.** Send your Skylit API key as a bearer token: Authorization: Bearer fs_live_ (`X-API-Key: fs_live_` is also accepted.) Your rate limit and monthly quota are determined by your account plan. **Rate limits & quotas.** Per-minute limits are enforced by the Skylit gateway and surfaced on every response via `X-RateLimit-Limit`, `X-RateLimit-Remaining`, and `X-RateLimit-Reset`. `429` includes `Retry-After`; quota exhaustion returns `403` with `code: QUOTA_EXCEEDED`. **Credits & billing.** Every `/v1/*` data request debits a fixed number of **credits** from your account's shared Skylit balance (the same balance used across all Skylit public APIs). Each chargeable response carries `X-Credits-Remaining: `. The credit is charged before the request is served, so a `5xx` still bills. Cost is priced by server-side work and data volume returned: | Tier | Credits | Routes | |------|--------:|--------| | Light | 1 | single-key reads, ratios, scores, discovery/search lists, expirations, rvol, per-contract bull/bear, the flow feed | | Medium | 3 | charts, full chains, by-strike matrix, momentum/baseline/strikes, tide, aggregate, sweeps, market, sector, market-breadth, chain bull/bear, unusual-volume/oi screeners | | Heavy | 5 | trade feeds (`/trades`), history (`/history`, `historical-compare`), bulk endpoints | `/v1/openapi.json` is free. When you run out of credits the API returns `402` `insufficient_credits`; a suspended account returns `403` `account_suspended`; a transient billing-store error returns `503` `credit_check_failed` (safe to retry). These billing codes are lowercase (`insufficient_credits`, `account_suspended`, `credit_check_failed`) — the platform-wide convention for credit errors. **Response envelope.** All success responses share one shape: { "data": , "meta": { "timestamp": "...", "requestId": "..." } } All errors share one shape: { "error": { "code": "NOT_FOUND", "message": "..." } } Field names are camelCase throughout. Codes are stable, machine-readable `SCREAMING_SNAKE_CASE` strings — the message text may evolve. **Freshness.** Endpoints with a `timeframe` parameter (e.g. `/v1/flow/{ticker}`) return data through the last completed bucket. Intra-bucket fills land on the next request. The cumulative `/v1/flow/market-breadth` and aggregate scoring endpoints update at most once per second. servers: - url: https://flow-api.skylit.ai description: Production - url: https://d2kehby0dtx1a6.cloudfront.net description: Staging (subject to wipes; do not use for billing-relevant work) security: - bearerApiKey: [] tags: - name: Flow description: Per-ticker flow feed, aggregate scoring, baselines, and momentum. - name: Sweeps description: Aggregated multi-exchange sweeps and sweep-only feeds. - name: Sector description: Sector- and industry-level flow rollups. - name: Market description: >- Market-wide overview, breadth, advance/decline, sector rotation, and net-premium tide. - name: Analytics description: > Standalone analytics endpoints — Vol/OI accumulation, moneyness segmentation, and timeframe-aggregated sentiment scores. - name: Ratios description: | Bid/ask/mid distribution analyses at chain and contract granularity, plus call/put-aware bull/bear pressure breakdowns. - name: Scoring description: Per-trade scoring, sentiment, and intent classification. - name: Underlying description: | Ticker-level discovery and analytics — top tickers by flow, bulk stats, intraday chart bars, raw enriched trades, strike / expiration distributions, option chain, and historical rollups. - name: Contract description: | Per-contract discovery and analytics — top contracts by flow, unusual volume / OI scans, contract stats, intraday chart bars, raw enriched trades, and historical rollups. - name: Meta description: API metadata (this OpenAPI document, etc.). paths: /v1/underlying: get: tags: - Underlying summary: List underlyings active on a date description: | Lists every ticker that traded options on the requested date, ordered by total premium (descending). Useful as a starting point for discovery or for repopulating the universe of tradable tickers. operationId: listUnderlyings parameters: - $ref: '#/components/parameters/DiscoveryLimit' - $ref: '#/components/parameters/DateQuery' - in: query name: minPremium schema: type: number format: double minimum: 0 description: Minimum total premium (USD) for the day. - in: query name: minVolume schema: type: integer minimum: 0 description: Minimum total option volume for the day. responses: '200': description: Tickers ranked by total premium. content: application/json: schema: $ref: '#/components/schemas/TickerListSuccess' '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/Unauthorized' '402': $ref: '#/components/responses/InsufficientCredits' '403': $ref: '#/components/responses/Forbidden' '429': $ref: '#/components/responses/RateLimited' components: parameters: DiscoveryLimit: name: limit in: query required: false description: Maximum rows to return. schema: type: integer minimum: 1 maximum: 200 default: 50 DateQuery: name: date in: query required: false description: | Trading date the request targets, in `YYYY-MM-DD`. Defaults to the current trading date (the most recent session that has settled enough data to be queryable). Past dates fall through to the daily rollup tables. schema: type: string format: date example: '2026-05-27' schemas: TickerListSuccess: type: object required: - data - meta properties: data: type: array items: $ref: '#/components/schemas/TickerListItem' meta: $ref: '#/components/schemas/Meta' TickerListItem: type: object required: - ticker - totalPremium - totalVolume properties: ticker: type: string example: SPY totalPremium: type: number format: double description: Total premium (USD) across all option trades on the day. totalVolume: type: integer minimum: 0 description: Total option contracts traded. Meta: type: object required: - timestamp - requestId properties: timestamp: type: string format: date-time description: Server-side timestamp the response was generated at. requestId: type: string description: Short opaque ID for log correlation. example: d7574836 Error: type: object required: - error properties: error: type: object required: - code - message properties: code: type: string description: | Stable machine-readable error code. Common values: `BAD_REQUEST`, `UNAUTHORIZED`, `FORBIDDEN`, `NOT_FOUND`, `RATE_LIMITED`, `QUOTA_EXCEEDED`, `INTERNAL_ERROR`, `UNAVAILABLE`. example: NOT_FOUND message: type: string description: Human-readable explanation. Wording may evolve; key off `code`. responses: BadRequest: description: Request validation failed. content: application/json: schema: $ref: '#/components/schemas/Error' examples: invalidParam: value: error: code: BAD_REQUEST message: >- Invalid parameter 'timeframe': must be one of [1m, 5m, 15m, 1h, 4h, 1d, 1w, 1M] Unauthorized: description: Missing or invalid API key. content: application/json: schema: $ref: '#/components/schemas/Error' examples: missingKey: value: error: code: UNAUTHORIZED message: Authentication required InsufficientCredits: description: >- The account's shared Skylit credit balance is lower than this route's cost. Top up to continue. Carries `X-Credits-Remaining: 0`. headers: X-Credits-Remaining: description: Remaining credit balance (0 on this response). schema: type: integer content: application/json: schema: $ref: '#/components/schemas/Error' examples: outOfCredits: value: error: code: insufficient_credits message: Out of credits. Top up to continue making requests. Forbidden: description: >- API key revoked/expired, monthly quota exceeded, or the account's API access is suspended (`account_suspended`). content: application/json: schema: $ref: '#/components/schemas/Error' examples: quotaExhausted: value: error: code: QUOTA_EXCEEDED message: Monthly quota for this API key has been exhausted. accountSuspended: value: error: code: account_suspended message: >- API access has been suspended for this account. Contact support. RateLimited: description: Per-minute rate limit exceeded. headers: Retry-After: schema: type: integer content: application/json: schema: $ref: '#/components/schemas/Error' examples: tooFast: value: error: code: RATE_LIMITED message: Rate limit of 100 req/min exceeded. Retry after 18s. securitySchemes: bearerApiKey: type: http scheme: bearer bearerFormat: fs_live_* description: | Skylit API key in the `Authorization` header (`Authorization: Bearer fs_live_`). `X-API-Key` is also accepted. ````