The WebSocket Event Stream API


The WebSocket Event Stream runs on a different port than the Web API. The default port for the Web API is 9984, while the one for the Event Stream is 9985.

BigchainDB provides real-time event streams over the WebSocket protocol with the Event Stream API. Connecting to an event stream from your application enables a BigchainDB node to notify you as events occur, such as new valid transactions.

Demoing the API

You may be interested in demoing the Event Stream API with the WebSocket echo test to familiarize yourself before attempting an integration.

Determining Support for the Event Stream API

It’s a good idea to make sure that the node you’re connecting with has advertised support for the Event Stream API. To do so, send a HTTP GET request to the node’s API Root Endpoint (e.g. http://localhost:9984/api/v1/) and check that the response contains a streams property:

 "streams": "ws://",

Connection Keep-Alive

The Event Stream API supports Ping/Pong frames as descibed in RFC 6455.


It might not be possible to send PING/PONG frames via web browsers because of non availability of Javascript API on different browsers to achieve the same.


Each stream is meant as a unidirectional communication channel, where the BigchainDB node is the only party sending messages. Any messages sent to the BigchainDB node will be ignored.

Streams will always be under the WebSocket protocol (so ws:// or wss://) and accessible as extensions to the /api/v<version>/streams/ API root URL (for example, valid transactions would be accessible under /api/v1/streams/valid_transactions). If you’re running your own BigchainDB instance and need help determining its root URL, then see the page titled Determining the API Root URL.

All messages sent in a stream are in the JSON format.


For simplicity, BigchainDB initially only provides a stream for all committed transactions. In the future, we may provide streams for other information. We may also provide the ability to filter the stream for specific qualities, such as a specific output’s public_key.

If you have specific use cases that you think would fit as part of this API, consider creating a new BEP.

Valid Transactions


Streams an event for any newly valid transactions committed to a block. Message bodies contain the transaction’s ID, associated asset ID, and containing block’s height.

Example message:

    "transaction_id": "<sha3-256 hash>",
    "asset_id": "<sha3-256 hash>",
    "height": <int>


Transactions in BigchainDB are committed in batches (“blocks”) and will, therefore, be streamed in batches.