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 WebSockets.

Limitations and considerations

Keep in mind the following limitations and considerations:

  • WebSockets is not compatible with shielding or the Fastly Next-Gen WAF.
  • When adding a host to your Fastly service configuration, only the Name, Address, Enable TLS, and Override Host origin server settings are supported with WebSockets.
  • When handling a WebSocket request, vcl_log will run at the time the request is accepted rather than when the connection ends.
  • Client request headers that are added, removed, or modified on your Request (or req.http in VCL) will be reflected in the WebSocket handoff.
  • If you have TLS certificates on your origin server, they must be signed by a public certification authority. Self-signed TLS certificates are not supported.


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 for each connection in usage minutes (rounded up to whole minutes) and aggregated monthly to millions of minutes. Bandwidth is included as part of your overall delivery bandwidth rate in your monthly billing statement.

For more details about this product, including how to purchase it, contact your account manager or email sales@fastly.com.

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