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This connector captures stock trade data from the Alpaca Market Data API into a Flow collection.

It is available for use in the Flow web application. For local development or open-source workflows, provides the latest version of the connector as a Docker image. You can also follow the link in your browser to see past image versions.

Real-time and historical trade data

The Alpaca Market Data API comprises multiple APIs for stock trades, including the Trades REST API for historical trade data and websocket streaming via the Data API for real-time trade data.

Historical trade data is available from the Alpaca Market Data API starting 01-01-2016. As such, the connector configuration requires a start date for the backfill to be on or after 01-01-2016.

This connector uses both APIs to capture historical and real-time data in parallel. It uses the Trades API to perform a historical backfill starting from the start date you specify and stopping when it reaches the present. At the same time, the connector uses websocket streaming to initiate a real-time stream of trade data starting at the present moment and continuing indefinitely until you stop the capture process.

As a result, you'll get data from a historical time period you specify, as well as the lowest-latency possible updates of new trade data, but there will be some overlap in the two data streams. See limitations to learn more about reconciling historical and real-time data.

Supported data resources

Alpaca supports over 8000 stocks and EFTs. You simply supply a list of symbols to Flow when you configure the connector. To check whether Alpaca supports a symbol, you can use the Alpaca Broker API.

You can use this connector to capture data from up to 20 stock symbols into Flow collections in a single capture (to add more than 20, set up multiple captures). For a given capture, data from all symbols is captured to a single collection.


To use this connector, you'll need:

  • An Alpaca account.

    • To access complete stock data in real-time, you'll need the Unlimited plan. To access a smaller sample of trade data with a 15-minute delay, you can use a Free plan, making sure to set Feed to iex and choose the Free Plan option when configuring the connector.
  • Your Alpaca API Key ID and Secret Key.


You configure connectors either in the Flow web app, or by directly editing the catalog specification file. See connectors to learn more about using connectors. The values and specification sample below provide configuration details specific to the Alpaca source connector.



/advancedAdvanced OptionsOptions for advanced users. You should not typically need to modify these.object
/advanced/disable_backfillDisable Historical Data BackfillDisables historical data backfill via the historical data API. Data will only be collected via streaming.boolean
/advanced/disable_real_timeDisable Real-Time StreamingDisables real-time streaming via the websocket API. Data will only be collected via the backfill mechanism.boolean
/advanced/is_free_planFree PlanSet this if you are using a free plan. Delays data by 15 minutes.boolean
/advanced/max_backfill_intervalMaximum Backfill IntervalThe largest time interval that will be requested for backfills. Using smaller intervals may be useful when tracking many symbols. Must be a valid Go duration string.string
/advanced/min_backfill_intervalMinimum Backfill IntervalThe smallest time interval that will be requested for backfills after the initial backfill is complete. Must be a valid Go duration string.string
/advanced/stop_dateStop DateStop backfilling historical data at this date.string
/api_key_idAlpaca API Key IDYour Alpaca API key ID.stringRequired
/api_secret_keyAlpaca API Secret KeyYour Alpaca API Secret key.stringRequired
/feedFeedThe feed to pull market data from. Choose from iex or sip; set iex if using a free plan.stringRequired
/start_dateStart DateGet trades starting at this date. Has no effect if changed after the capture has started. Must be no earlier than 2016-01-01T00:00:00Z.stringRequired
/symbolsSymbolsComma separated list of symbols to monitor.stringRequired


/nameNameUnique name for this binding. Cannot be changed once set.stringRequired


image: ""
api_key_id: <SECRET>
api_secret_key: <SECRET>
feed: iex
start_date: 2022-11-01T00:00:00Z
is_free_plan: true
- resource:
name: trades
target: ${PREFIX}/${CAPTURE_NAME}/trades


Capturing data for more than 20 symbols in a single capture could result in API errors.

If you need to capture data for more than 20 symbols, we recommend splitting them between two captures. Support for a larger number of symbols in a single capture is planned for a future release.

Separate historical and real-time data streams will result in some duplicate trade documents.

As discussed above, the connector captures historical and real-time data in two different streams. As the historical data stream catches up to the present, it will overlap with the beginning of the real-time data stream, resulting in some duplicated documents. These will have identical properties from Alpaca, but different metadata from Flow.

There are several ways to resolve this:

  • If you plan to materialize to an endpoint for which standard (non-delta) updates are supported, Flow will resolve the duplicates during the materialization process. Unless otherwise specified in their documentation page, materialization connectors run in standard updates mode. If a connector supports both modes, it will default to standard updates.

  • If you plan to materialize to an endpoint for which delta updates is the only option, ensure that the endpoint system supports the equivalent of lastWriteWins reductions.