> ## 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. # Chain-level bid/ask/mid distribution > Aggregates a ticker's full option chain to surface buying vs selling pressure (`askRatio`, `bidRatio`, `midRatio`, `aggressionRatio`), call/put balance, and ATM/OTM concentration. Returns a `bias`, `aggression`, and `confidence` interpretation. Reference: PRD Sections 12.3 and 14. ## OpenAPI ````yaml /flowseeker-openapi.yaml get /v1/chain-ratio/{ticker} 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/chain-ratio/{ticker}: get: tags: - Ratios summary: Chain-level bid/ask/mid distribution description: | Aggregates a ticker's full option chain to surface buying vs selling pressure (`askRatio`, `bidRatio`, `midRatio`, `aggressionRatio`), call/put balance, and ATM/OTM concentration. Returns a `bias`, `aggression`, and `confidence` interpretation. Reference: PRD Sections 12.3 and 14. operationId: getChainRatio parameters: - $ref: '#/components/parameters/Ticker' - name: date in: query required: false schema: type: string format: date - name: timeframe in: query required: false schema: type: string enum: - 5m - 15m - 1h - 4h - 1d default: 1d - name: optionType in: query required: false schema: type: string enum: - call - put - all default: all - name: minPremium in: query required: false schema: type: integer minimum: 0 - name: minDte in: query required: false schema: type: integer minimum: 0 - name: maxDte in: query required: false schema: type: integer minimum: 0 responses: '200': description: Chain ratio analysis with interpretation. content: application/json: schema: $ref: '#/components/schemas/ChainRatioSuccess' '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/Unauthorized' '402': $ref: '#/components/responses/InsufficientCredits' '403': $ref: '#/components/responses/Forbidden' '404': $ref: '#/components/responses/NotFound' '429': $ref: '#/components/responses/RateLimited' '503': $ref: '#/components/responses/Unavailable' components: parameters: Ticker: name: ticker in: path required: true description: Underlying ticker symbol (uppercase, e.g. `SPY`, `AAPL`). schema: type: string example: SPY schemas: ChainRatioSuccess: type: object required: - data - meta properties: data: $ref: '#/components/schemas/ChainRatioResponse' meta: $ref: '#/components/schemas/Meta' ChainRatioResponse: type: object required: - ticker - date - timeframe - tradeCount - totalPremium - chainRatios - interpretation properties: ticker: type: string date: type: string format: date timeframe: type: string tradeCount: type: integer minimum: 0 totalPremium: type: number chainRatios: $ref: '#/components/schemas/ChainRatios' interpretation: $ref: '#/components/schemas/RatioInterpretation' 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`. ChainRatios: type: object required: - callPutRatio - askRatio - bidRatio - midRatio - aggressionRatio - atmConcentration - otmCallConcentration - otmPutConcentration properties: callPutRatio: type: number description: Call premium / put premium (capped at 999 when puts = 0). askRatio: type: number description: Share (0–1) of trades at or above ask. bidRatio: type: number description: Share (0–1) of trades at or below bid. midRatio: type: number description: Share (0–1) of trades at mid (or with no BBO). aggressionRatio: type: number description: >- (askTrades + bidTrades) / midTrades — capped at 999 when midTrades = 0. atmConcentration: type: number description: Share (0–1) of volume in ATM strikes (±3% moneyness). otmCallConcentration: type: number description: Share (0–1) of call volume in OTM strikes. otmPutConcentration: type: number description: Share (0–1) of put volume in OTM strikes. RatioInterpretation: type: object required: - bias - aggression - confidence - description properties: bias: type: string enum: - BULLISH - BEARISH - NEUTRAL - MIXED aggression: type: string enum: - HIGH - MEDIUM - LOW confidence: type: string enum: - HIGH - MEDIUM - LOW description: type: string 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. NotFound: description: Unknown resource (ticker / sector / window with no data). content: application/json: schema: $ref: '#/components/schemas/Error' examples: noData: value: error: code: NOT_FOUND message: No trades found for AAPL on 2026-05-27 with timeframe 1d 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. Unavailable: description: >- Underlying data source temporarily unavailable, or the credit balance could not be verified (`credit_check_failed`). Safe to retry. content: application/json: schema: $ref: '#/components/schemas/Error' examples: ingestionLag: value: error: code: UNAVAILABLE message: Live feed is degraded; please retry in a few seconds. creditCheckFailed: value: error: code: credit_check_failed message: Could not verify credit balance. Please retry. 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. ````