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Alpaca API python client

Project description

PyPI version CircleCI Updates Python 3


alpaca-trade-api-python is a python library for the Alpaca Commission Free Trading API. It allows rapid trading algo development easily, with support for both REST and streaming data interfaces. For details of each API behavior, please see the online API document.

Note that this package supports only python version 3.6 and above, due to the async/await and websockets module dependency.


We support python>=3.6. If you want to work with python 3.6, please note that these package dropped support for python <3.7 for the following versions:

pandas >= 1.2.0
numpy >= 1.20.0
scipy >= 1.6.0

The solution - manually install these package before installing alpaca-trade-api. e.g:

pip install pandas==1.1.5 numpy==1.19.4 scipy==1.5.4

Installing using pip

$ pip3 install alpaca-trade-api

API Keys

To use this package you first need to obtain an API key. Go here to signup


These services are provided by Alpaca:

The free services are limited, please check the docs to see the differences between paid/free services.

Alpaca Environment Variables

The Alpaca SDK will check the environment for a number of variables that can be used rather than hard-coding these into your scripts.
Alternatively you could pass the credentials directly to the SDK instances.

Environment default Description
APCA_API_KEY_ID=<key_id> Your API Key
APCA_API_SECRET_KEY=<secret_key> Your API Secret Key
APCA_API_BASE_URL=url (for live) Specify the URL for API calls, Default is live, you must specify to switch to paper endpoint!
APCA_API_DATA_URL=url Endpoint for data API
APCA_RETRY_MAX=3 3 The number of subsequent API calls to retry on timeouts
APCA_RETRY_WAIT=3 3 seconds to wait between each retry attempt
APCA_RETRY_CODES=429,504 429,504 comma-separated HTTP status code for which retry is attempted
DATA_PROXY_WS When using the alpaca-proxy-agent you need to set this environment variable as described here

Working with Data

Historic Data

You could get one of these historic data types:

  • Bars
  • Quotes
  • Trades First thing to understand is the new data polling mechanism. You could query up to 10000 items, and the API is using a pagination mechanism to provide you with the data.
    You now have 2 options:
  • Working with data as it is received with a generator. (meaning it's faster but you need to process each item alone)
  • Wait for the entire data to be received, and then work with it as a list or dataframe. We provide you with both options to choose from.


option 1: wait for the data

from import REST
api = REST()

api.get_bars("AAPL", TimeFrame.Hour, "2021-02-08", "2021-02-08", limit=10, adjustment='raw').df

                               open    high      low     close    volume
2021-02-08 09:00:00+00:00  136.6800  137.15  136.450  136.9600     38707
2021-02-08 10:00:00+00:00  136.9600  137.08  136.800  136.8300     22334
2021-02-08 11:00:00+00:00  136.8300  136.97  136.710  136.9100     19546
2021-02-08 12:00:00+00:00  136.9000  136.97  136.050  136.2200    483167
2021-02-08 13:00:00+00:00  136.2200  136.25  136.010  136.1700    307755
2021-02-08 14:00:00+00:00  136.1525  136.35  134.920  135.6900  12159693
2021-02-08 15:00:00+00:00  135.6800  136.68  135.595  136.6100   8076122
2021-02-08 16:00:00+00:00  136.6800  136.91  135.040  136.2350   8484923
2021-02-08 17:00:00+00:00  136.2400  136.54  135.030  135.9745   4610247
2021-02-08 18:00:00+00:00  135.9799  136.30  135.800  135.9330   3375300

option 2: iterate over bars

def process_bar(bar):
    # process bar

bar_iter = api.get_bars_iter("AAPL", TimeFrame.Hour, "2021-02-08", "2021-02-08", limit=10, adjustment='raw')
for bar in bar_iter:


option 1: wait for the data

from import REST
api = REST()

api.get_quotes("AAPL", "2021-02-08", "2021-02-08", limit=10).df

                                    ask_exchange  ask_price  ask_size bid_exchange  bid_price  bid_size conditions
2021-02-08 09:02:07.697204555+00:00            Q     136.80         1            P     136.52         1        [R]
2021-02-08 09:02:07.706401536+00:00            Q     136.80         1            P     136.56         2        [R]
2021-02-08 09:02:07.837365238+00:00            P     136.81         1            P     136.56         2        [R]
2021-02-08 09:02:07.838885705+00:00            Q     136.79         1            P     136.56         2        [R]
2021-02-08 09:02:30.946732544+00:00            P     136.64         1            P     136.50         1        [R]
2021-02-08 09:02:32.558048512+00:00            P     136.64         1            P     136.37         1        [R]
2021-02-08 09:02:32.794415360+00:00            Q     136.69         1            P     136.37         1        [R]
2021-02-08 09:02:32.795173632+00:00            P     136.62         1            P     136.37         1        [R]
2021-02-08 09:02:33.969686528+00:00            Q     136.69         1            P     136.37         1        [R]
2021-02-08 09:02:34.069692672+00:00            P     136.55         1            P     136.37         1        [R]

option 2: iterate over quotes

def process_quote(quote):
    # process quote

quote_iter = api.get_quotes_iter("AAPL", "2021-02-08", "2021-02-08", limit=10)
for quote in quote_iter:


option 1: wait for the data

from import REST
api = REST()

api.get_trades("AAPL", "2021-02-08", "2021-02-08", limit=10).df

                                    exchange   price  size conditions  id tape
2021-02-08 09:00:11.764828160+00:00        P  136.68     1  [@, T, I]  46    C
2021-02-08 09:00:13.885322240+00:00        P  136.75    35  [@, T, I]  49    C
2021-02-08 09:00:13.885322240+00:00        P  136.75    10  [@, T, I]  48    C
2021-02-08 09:00:13.885322240+00:00        P  136.68    28  [@, T, I]  47    C
2021-02-08 09:00:17.024569856+00:00        P  136.61    16  [@, T, I]  50    C
2021-02-08 09:00:17.810107904+00:00        P  136.66     1  [@, T, I]  51    C
2021-02-08 09:00:19.932405248+00:00        P  136.68    25  [@, T, I]  55    C
2021-02-08 09:00:19.932405248+00:00        P  136.75    18  [@, T, I]  56    C
2021-02-08 09:00:19.932405248+00:00        P  136.68    11  [@, T, I]  54    C
2021-02-08 09:00:19.932405248+00:00        P  136.67    10  [@, T, I]  53    C

option 2: iterate over trades

def process_trade(trade):
    # process trade

trades_iter = api.get_trades_iter("AAPL", "2021-02-08", "2021-02-08", limit=10)
for trade in trades_iter:

Live Stream Data

There are 2 streams available as described here.
The free plan is using the iex stream, while the paid subscription is using the sip stream.
You could subscribe to bars, trades or quotes and accoutn updates as well.
Under the example folder you could find different code samples to achieve different goals. Let's see the basic example
We present a new Streamer class under for API V2.

async def trade_callback(t):
    print('trade', t)

async def quote_callback(q):
    print('quote', q)

# Initiate Class Instance
stream = Stream(<ALPACA_API_KEY>,
                data_feed='iex')  # <- replace to SIP if you have PRO subscription

# subscribing to event
stream.subscribe_trades(trade_callback, 'AAPL')
stream.subscribe_quotes(quote_callback, 'IBM')

Acount & Portfolio Management

The HTTP API document is located at

API Version

API Version now defaults to 'v2', however, if you still have a 'v1' account, you may need to specify api_version='v1' to properly use the API until you migrate.


The Alpaca API requires API key ID and secret key, which you can obtain from the web console after you sign in. You can pass key_id and secret_key to the initializers of REST or StreamConn as arguments, or set up environment variables as outlined below.


The REST class is the entry point for the API request. The instance of this class provides all REST API calls such as account, orders, positions, and bars.

Each returned object is wrapped by a subclass of the Entity class (or a list of it). This helper class provides property access (the "dot notation") to the json object, backed by the original object stored in the _raw field. It also converts certain types to the appropriate python object.

import alpaca_trade_api as tradeapi

api = tradeapi.REST()
account = api.get_account()

The Entity class also converts the timestamp string field to a pandas.Timestamp object. Its _raw property returns the original raw primitive data unmarshaled from the response JSON text.

Please note that the API is throttled, currently 200 requests per minute, per account. If your client exceeds this number, a 429 Too many requests status will be returned and this library will retry according to the retry environment variables as configured.

If the retries are exceeded, or other API error is returned, is raised. You can access the following information through this object.

  • the API error code: .code property
  • the API error message: str(error)
  • the original request object: .request property
  • the original response objecgt: .response property
  • the HTTP status code: .status_code property

API REST Methods

Rest Method End Point Result
get_account() GET /account and Account entity.
get_order_by_client_order_id(client_order_id) GET /orders with client_order_id Order entity.
list_orders(status=None, limit=None, after=None, until=None, direction=None, nested=None) GET /orders list of Order entities. after and until need to be string format, which you can obtain by pd.Timestamp().isoformat()
submit_order(symbol, qty=None, side="buy", type="market", time_in_force="day", limit_price=None, stop_price=None, client_order_id=None, order_class=None, take_profit=None, stop_loss=None, trail_price=None, trail_percent=None, notional=None) POST /orders Order entity.
get_order(order_id) GET /orders/{order_id} Order entity.
cancel_order(order_id) DELETE /orders/{order_id}
cancel_all_orders() DELETE /orders
list_positions() GET /positions list of Position entities
get_position(symbol) GET /positions/{symbol} Position entity.
list_assets(status=None, asset_class=None) GET /assets list of Asset entities
get_asset(symbol) GET /assets/{symbol} Asset entity
get_barset(symbols, timeframe, limit, start=None, end=None, after=None, until=None) GET /bars/{timeframe} Barset with limit Bar objects for each of the the requested symbols. timeframe can be one of minute, 1Min, 5Min, 15Min, day or 1D. minute is an alias of 1Min. Similarly, day is an alias of 1D. start, end, after, and until need to be string format, which you can obtain with pd.Timestamp().isoformat() after cannot be used with start and until cannot be used with end.
get_aggs(symbol, timespan, multiplier, _from, to) GET /aggs/ticker/{symbol}/range/{multiplier}/{timespan}/{from}/{to} Aggs entity. multiplier is the size of the timespan multiplier. timespan is the size of the time window, can be one of minute, hour, day, week, month, quarter or year. _from and to must be in YYYY-MM-DD format, e.g. 2020-01-15.
get_last_trade(symbol) GET /last/stocks/{symbol} Trade entity
get_last_quote(symbol) GET /last_quote/stocks/{symbol} Quote entity
get_clock() GET /clock Clock entity
get_calendar(start=None, end=None) GET /calendar Calendar entity
get_portfolio_history(date_start=None, date_end=None, period=None, timeframe=None, extended_hours=None) GET /account/portfolio/history PortfolioHistory entity. PortfolioHistory.df can be used to get the results as a dataframe

Rest Examples

Please see the examples/ folder for some example scripts that make use of this API

Using submit_order()

Below is an example of submitting a bracket order.


For simple orders with type='market' and time_in_force='day', you can pass a fractional amount (qty) or a notional amount (but not both). For instace, if the current market price for SPY is $300, the following calls are equivalent:

    qty=1.5,  # fractional shares
    notional=450,  # notional value of 1.5 shares of SPY at $300
Using get_barset() (Deprecated. use get_bars() instead)
import pandas as pd
NY = 'America/New_York'
start=pd.Timestamp('2020-08-01', tz=NY).isoformat()
end=pd.Timestamp('2020-08-30', tz=NY).isoformat()
print(api.get_barset(['AAPL', 'GOOG'], 'day', start=start, end=end).df)

# Minute data example
start=pd.Timestamp('2020-08-28 9:30', tz=NY).isoformat()
end=pd.Timestamp('2020-08-28 16:00', tz=NY).isoformat()
print(api.get_barset(['AAPL', 'GOOG'], 'minute', start=start, end=end).df)

please note that if you are using limit, it is calculated from the end date. and if end date is not specified, "now" is used.
Take that under consideration when using start date with a limit.


Websocket exceptions may occur during execution. It will usually happen during the consume() method, which basically is the websocket steady-state.
exceptions during the consume method may occur due to:

  • server disconnections
  • error while handling the response data

We handle the first issue by reconnecting the websocket every time there's a disconnection. The second issue, is usually a user's code issue. To help you find it, we added a flag to the StreamConn object called debug. It is set to False by default, but you can turn it on to get a more verbose logs when this exception happens. Turn it on like so StreamConn(debug=True)


You should define a logger in your app in order to make sure you get all the messages from the different components.
It will help you debug, and make sure you don't miss issues when they occur.
The simplest way to define a logger, if you have no experience with the python logger - will be something like this:

import logging
logging.basicConfig(format='%(asctime)s %(message)s', level=logging.INFO)

Websocket best practices

Under the examples folder you could find several examples to do the following:

  • Different subscriptions(channels) usage with the alpaca streams
  • pause / resume connection
  • change subscriptions/channels of existing connection
  • ws disconnections handler (make sure we reconnect when the internal mechanism fails)

Running Multiple Strategies

There's a way to execute more than one algorithm at once.
The websocket connection is limited to 1 connection per account.
For that exact purpose this project was created
The steps to execute this are:

  • Run the Alpaca Proxy Agent as described in the project's README
  • Define this env variable: DATA_PROXY_WS to be the address of the proxy agent. (e.g: DATA_PROXY_WS=ws://
  • If you are using the Alpaca data stream, make sure you you initiate the StreamConn object with the container's url, like so: data_url=''
  • execute your algorithm. it will connect to the servers through the proxy agent allowing you to execute multiple strategies

Raw Data vs Entity Data

By default the data returned from the api or streamed via StreamConn is wrapped with an Entity object for ease of use.
Some users may prefer working with raw python objects (lists, dicts, ...).
You have 2 options to get the raw data:

  • Each Entity object as a _raw property that extract the raw data from the object.
  • If you only want to work with raw data, and avoid casting to Entity (which may take more time, casting back and forth)
    you could pass raw_data argument to Rest() object or the StreamConn() object.

Support and Contribution

For technical issues particular to this module, please report the issue on this GitHub repository. Any API issues can be reported through Alpaca's customer support.

New features, as well as bug fixes, by sending a pull request is always welcomed.

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