These VCL variables are supported by Fastly.

Date and time

By default VCL includes the now variable, which provides the current time (for example, Mon, 02 Jan 2006 22:04:05 GMT). Fastly adds several new Varnish variables and functions that allow more flexibility when dealing with dates and times.

Edge Side Includes (ESI)

Fastly exposes tools to allow you to track a request that has ESI.


Fastly exposes a number of geographic variables for you to take advantage of inside VCL for both IPv4 and IPv6 client IPs.

Math constants and limits

Features that support various math constants and limits.


Fastly has added several miscellaneous features to Varnish that don't easily fit into specific categories.

Segmented Caching

Variables related to controlling range requests via Segmented Caching.


Variables relating to the server receiving the request.


To allow better reporting, Fastly has added several variables to VCL to give more insight into what happened in a request.

TCP info

Variables that provide TCP information.


Fastly has added several variables that expose information about the TLS and HTTP attributes of a request.