openapi: 3.0.3
info:
  title: Alpaca API (Trading, Market Data, Broker) Account Market Data - Screener API
  description: A grounded, curated OpenAPI description of Alpaca's public REST surface. Alpaca is a developer-first, commission-free brokerage whose stock, ETF, options, and crypto trading and market data are exposed entirely through APIs. This document covers the three REST products - the Trading API (api.alpaca.markets/v2, with a free paper sandbox at paper-api.alpaca.markets/v2), the Market Data API (data.alpaca.markets, with v2 stocks, v1beta3 crypto, and v1beta1 options/news/screener namespaces), and the Broker API (broker-api.alpaca.markets/v1). Real-time WebSocket streaming for market data is described in the companion AsyncAPI document at asyncapi/alpaca-markets-asyncapi.yml. Trading and Market Data authenticate with the APCA-API-KEY-ID and APCA-API-SECRET-KEY headers (or OAuth2 for third-party apps); the Broker API uses HTTP Basic auth. This spec is a representative subset of the full API for discovery purposes, not an exhaustive vendor specification.
  version: '1.0'
  contact:
    name: Alpaca
    url: https://alpaca.markets
  license:
    name: API documentation - Alpaca Terms of Service
    url: https://alpaca.markets/terms
servers:
- url: https://api.alpaca.markets/v2
  description: Trading API - live
- url: https://paper-api.alpaca.markets/v2
  description: Trading API - paper (free sandbox)
- url: https://data.alpaca.markets
  description: Market Data API
- url: https://broker-api.alpaca.markets/v1
  description: Broker API - production
security:
- apcaKey: []
  apcaSecret: []
tags:
- name: Market Data - Screener
  description: Most-actives and movers screeners (v1beta1).
paths:
  /v1beta1/screener/stocks/most-actives:
    servers:
    - url: https://data.alpaca.markets
      description: Market Data API
    get:
      operationId: getMostActives
      tags:
      - Market Data - Screener
      summary: Get most active stocks
      description: Returns the most active stocks by volume or trade count. Full path is https://data.alpaca.markets/v1beta1/screener/stocks/most-actives.
      parameters:
      - name: by
        in: query
        schema:
          type: string
          enum:
          - volume
          - trades
        description: Ranking metric.
      - name: top
        in: query
        schema:
          type: integer
          default: 10
        description: Number of results to return.
      responses:
        '200':
          description: Most active stocks.
          content:
            application/json:
              schema:
                type: object
components:
  securitySchemes:
    apcaKey:
      type: apiKey
      in: header
      name: APCA-API-KEY-ID
      description: Alpaca API key ID. Paired with APCA-API-SECRET-KEY.
    apcaSecret:
      type: apiKey
      in: header
      name: APCA-API-SECRET-KEY
      description: Alpaca API secret key. Paired with APCA-API-KEY-ID.
    brokerBasic:
      type: http
      scheme: basic
      description: Broker API HTTP Basic auth using your Broker API key as username and secret as password.