Fastly supports the use of the WebSocket protocol. This protocol allows you to establish long-lived, two-way, interactive communication sessions between an end user's client (such as a web browser) and your servers.


To use the WebSocket protocol, you must purchase a paid account with a contract for Fastly's services.

Limitations and considerations

Keep in mind the following limitations and considerations during limited availability:

  • Only the Name, Address, Enable TLS, and Override Host origin server settings are supported.
  • When handling a WebSocket request, vcl_log will run at the time the request is accepted rather than when the connection ends.


Use of the WebSocket protocol is disabled by default. Anyone assigned the role of superuser or engineer can enable it directly in the web interface, which will result in changes to your monthly bill. When enabled, any user will be able to use this communications protocol to establish two-way, interactive communication sessions between clients and servers.

We base billing for WebSockets on a combination of bandwidth and connection time. Connection time is measured in usage minutes (rounded up to whole minutes) and aggregated monthly. Bandwidth is included as part of your overall delivery bandwidth rate in your monthly billing statement.

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