What constitutes an API call?

Alpaca Trading
1

Hi,

With Alpaca paid plan, you can make upto 10,000 API calls a minute. Now, what exactly constitutes an API call? If I query an option chain for AAPL, would that be considered one API call or multiple ones? Likewise would querying stock data for AAPL be considered one API call? If that is the case, querying option chain data and stock data for a single stock, should be considered 2 API calls, right?

Let me know if I am correct in my reasoning.

Thanks

2

Another related question. Since we are limited in the number of API calls we can make in a given time frame (10000 per minute), would that include the number of API calls made in a Paper account as well? So if we have 3 paper accounts and 1 live account, is the 10000 the maximum number of API calls we can make across all accounts?

Also, I understand that we can query option chain information directly, but is there a way to query data for a particular option symbol? Perhaps both may count as an API call, but the latter possibly could be more efficient I believe.

Thanks

3

@sarahvignale You asked about market data and rates specifically.

…what exactly constitutes an API call? [Would] querying option chain data and stock data for a single stock, should be considered 2 API calls?
An “API call” is a single HTTP request to an endpoint. For example, fetching option snapshots for several options as below would be 1 call. Fetching equity (stock) data would be a separate endpoint and a separate call.

"https://data.alpaca.markets/v1beta1/options/snapshots?symbols=AAPL241220C00300000%2CAAPL240315C00225000&feed=opra&limit=100"

Some endpoints return data in multiple pages if the data is too long. Each request for a new page is considered an API call (ie to get 3 pages would be 3 API calls).

Since we are limited in the number of API calls we can make in a given time frame (10000 per minute), would that include the number of API calls made in a Paper account as well? So if we have 3 paper accounts and 1 live account, is the 10000 the maximum number of API calls we can make across all accounts?
This is a good time to explain the difference between the Trading APIs and the Market Data APIs.

The trading APIs are used to submit orders, check account buying power, fetch open orders etc. All these APIs have a base URL of http://api.alpaca.markets or http://paper-api.alpaca.markets. These have a default API rate limit of 200/min per account (ie each paper and live account is separate). If one has an Elite account that rate can be increased to 1000/min. This is completely independent of one’s market data subscription. Subscribing to the Algo Trader Plus market data does not increase the Trading API rate limits.

The market data APIs are used to get price, quote, trade and other data not related to a specific account. All these APIs have a base URL of http://data.alpaca.markets. These have a default API rate limit of 200/min per owner (ie the owner of the data subscription can make that many calls). This is increased to 10,000 call/minute limit when subscribed to the Algo Trader Plus market data plan. It doesn’t matter how that data is used or which account it’s used for. One could even use the data to trade on another broker’s site. The only reason one supplies the account API keys is to look up the owner. Data is completely independent of the account. So, to answer the question “if we have 3 paper accounts and 1 live account, is the 10000 the maximum number of [market data] API calls we can make across all accounts?”. Yes, but again that is separate from the Trading API calls.

Also, I understand that we can query option chain information directly, but is there a way to query data for a particular option symbol? Perhaps both may count as an API call, but the latter possibly could be more efficient I believe.
I’m assuming this means “query option contract data by a particular underlying equity symbol”? The answer is yes. The option chain endpoint has this functionality. Note the default max snapshots returned per page is 100 but this can be increased to 1000 by setting limit=1000.

The 10,000 call/minute limit when subscribed to Algo Trader Plus market data plan should typically never be an issue. That is a lot of calls. Most endpoints allow querying multiple symbols (equity endpoints up to about 4000 and option endpoints typically up to 100). If one is fetching quotes for 4000 equity symbols, for example, that only counts as a single API call.

1 Like
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Thank you @Dan_Whitnable_Alpaca for this wonderful explanation. I am sure that it will be useful not just to me, but to many!

Also, I understand that we can query option chain information directly, but is there a way to query data for a particular option symbol? Perhaps both may count as an API call, but the latter possibly could be more efficient I believe.>

I actually meant options symbol and it looks like I have figured out a way to do the same. The following piece of code does the trick:

            option_latest_quote = \
                client.get_option_latest_quote(
                    OptionLatestQuoteRequest(<LIST of option symbols>))

This way, we can get information for few option symbols, rather than querying the entire option chain.

Anyways thanks for the wonderful explanation once again. Keep up the great job you are doing!

Thanks