Hoverfly can build responses dynamically through templating. This is particularly useful when combined with loose matching, as it allows a single matcher to represent an unlimited combination of responses.

Enabling Templating

By default templating is disabled. In order to enable it, set the templated field to true in the response of a simulation.

Getting data from the request

Currently, you can get the following data from request to the response via templating:

Field Example Request Result
Request scheme {{ Request.Scheme }} http://www.foo.com http
Query parameter value {{ Request.QueryParam.myParam }} http://www.foo.com?myParam=bar bar
Query parameter value (list) {{ Request.QueryParam.NameOfParameter.[1] }} http://www.foo.com?myParam=bar1&myParam=bar2 bar2
Path parameter value {{ Request.Path.[1] }} http://www.foo.com/zero/one/two one
Method {{ Request.Method }} http://www.foo.com/zero/one/two GET
jsonpath on body {{ Request.Body “jsonpath” “$.id” }} { “id”: 123, “username”: “hoverfly” } 123
xpath on body {{ Request.Body “xpath” “/root/id” }} <root><id>123</id></root> 123
Header value {{ Request.Header.X-Header-Id }} { “X-Header-Id”: [“bar”] } bar
Header value (list) {{ Request.Header.X-Header-Id.[1] }} { “X-Header-Id”: [“bar1”, “bar2”] } bar2
State {{ State.basket }} State Store = {“basket”:”eggs”} eggs

Helper Methods

Additional data can come from helper methods. These are the ones Hoverfly currently support:

Description Example Result

The current date time with offset, in the given format.

For example:

  • The current date time plus 1 day in unix timestamp
  • The current date time in ISO 8601 format
  • The current date time minus 1 day in custom format
  • {{ now “1d” “unix” }}
  • {{ now “” “” }}
  • {{ now “-1d” “2006-Jan-02” }}
  • 1136300645
  • 2006-01-02T15:04:05Z
  • 2006-Jan-01
A random string {{ randomString }} hGfclKjnmwcCds
A random string with a specified length {{ randomStringLength 2 }} KC
A random boolean {{ randomBoolean }} true
A random integer {{ randomInteger }} 42
A random integer within a range {{ randomIntegerRange 1 10 }} 7
A random float {{ randomFloat }} 42
A random float within a range {{ randomFloatRange 1.0 10.0 }} 7.4563213423
A random email address {{ randomEmail }} LoriStewart@Photolist.com
A random IPv4 address {{ randomIPv4 }}
A random IPv6 address {{ randomIPv6 }} 41d7:daa0:6e97:6fce:411e:681:f86f:e557
A random UUID {{ randomUuid }} 7b791f3d-d7f4-4635-8ea1-99568d821562

Replace all occurrences of the old value with the new

value in the target string

{{ replace Request.Body “be” “mock” }}

(where Request.Body has the value of “to be or not to be”

to mock or not to mock


The following helper methods will be deprecated, please use now helper for date time:
  • iso8601DateTime
  • iso8601DateTimePlusDays
  • currentDateTime
  • currentDateTimeAdd
  • currentDateTimeSubtract

Time offset

When using template helper method now, time offset must be formatted using the following syntax.

Shorthand Type
ns Nanosecond
us/µs Microsecond
ms Millisecond
s Second
m Minute
h Hour
d Day
y Year

Prefix an offset with - to subtract the duration from the current date time.

Example time offset

5m 5 minutes
1h30m 1 hour 5 minutes
1y10d 1 year 10 days

Date time formats

When using template helper method now, date time formats must follow the Golang syntax. More can be found out here https://golang.org/pkg/time/#Parse

Example date time formats

Mon, 02 Jan 2006 15:04:05 MST
Jan _2 15:04:05


If you leave the format string empty, the default format to be used is ISO 8601 (2006-01-02T15:04:05Z07:00).

You can also get an UNIX timestamp by setting the format to:

  • unix: UNIX timestamp in seconds
  • epoch: UNIX timestamp in milliseconds

Conditional Templating, Looping and More

Hoverfly uses the https://github.com/aymerick/raymond library for templating, which is based on http://handlebarsjs.com/

To learn about more advanced templating functionality, such as looping and conditionals, read the documentation for these projects.