Stream Data Using SSE#

We stream data using Server-Sent Events (SSE). We provide endpoints for streaming the following types of data:

The endpoints are available via the IEX Cloud Legacy API and described in the Legacy API Reference.

How Credits Work with Streaming#

For Apperate plans, each message received over the stream counts as a read.

1 million reads = 1 credit


Unlike other cloud databases that charge based on table scans and/or data blocks, a read on Apperate equates to getting a whole record/row.

US Stocks and Securities#

There are three types of endpoints for US stocks and securities. Two of them require a paid plan and a UTP agreement. Here’s an overview of these endpoints:

US Stocks Endpoints:


Response Data



- IEX real-time data
- 15 min delayed Nasdaq listed data (UTP)
- 15 min delayed NYSE listed data (CTA)

- Paid plan
- UTP agreement


- IEX real-time data
- 15 min delayed NYSE listed data (CTA)



- 15 min delayed OTC data

- Paid plan
- UTP agreement with OTC eligibility

Get Nasdaq-listed Stock Data (UTP/OTC Data) explains the UTP agreement process.

Firehose Versus Streaming on Symbols#

You can stream on specific symbols or stream everything – like drinking from a firehose.

The symbols query parameter enables you to stream on a specific symbol or comma-separated list of symbols. The examples below respectively demonstrate calling the stocksUS endpoint on specific symbols and all symbols.

Stream on symbols:

curl --header 'Accept: text/event-stream' ',msft&token=YOUR_TOKEN'


curl --header 'Accept: text/event-stream' ''

You can use the symbols parameter with all the streaming endpoints.


Firehose functionality does not apply to IEX DEEP streaming endpoints.


When you connect to an SSE endpoint, you receive a snapshot of the latest message and then receive updates as they are available. You can disable snapshots by using the query parameter setting nosnapshot=true.

You can also specify a starting point for a snapshot by using a query parameter setting snapshotAsOf=EPOCH_TIMESTAMP, where the value is in milliseconds since Epoch.

Interval Streaming#

Some data is available to stream at set intervals: 1 second, 5 seconds, or 1 minute. This helps make data delivery and credit usage more predictable. The endpoints below, for example, compliment the stocksUS endpoint.

1 second interval:

curl --header 'Accept: text/event-stream' ''

5 second interval:

curl --header 'Accept: text/event-stream' ''

1 minute interval:

curl --header 'Accept: text/event-stream' ''

What’s Next#

Now you’re familiar with some of the SSE Streaming endpoints. You can try more SSE Streaming endpoints as described in the Legacy API Reference.