Adding response rules#

After creating multiple responses for each route, you can create more complex scenarios and serve the responses depending on the fulfillment of rules.

Defining rules#

You can define an unlimited number of rules for each route. At each request, Mockoon will assert each response's rules and serve the response which contains the first matching rule(s). The rules are interpreted in the order they are declared: [rule OR|AND rule] OR [rule OR|AND rule], the brackets symbolizing each route response.

Rules interpretation order

To add a new rule to a response, go to the route response's Rules tab, click on "Add rule" and fill the fields:

Click on add and fill the fields

Reordering rules#

By default, rules are interpreted in the order you added them. You can change their interpretation order by drag and dropping them:

Drag and drop rules to reorder them

Disabling rules#

You can temporarily disable the rules and serve the default response only. To activate this option, click on the "rules" icon next to the response list:

Disable rules

When this option is active, the default response will be always served and all the rules defined on this route will be ignored. Also, this option cannot be selected in addition to the random or sequential responses.

Rules logical operator#

Inside a route response, rules are interpreted by default with the OR logical operator. When you have more than one rule in a route response, you can easily switch the operator applied when interpreting the rules, by clicking on the OR|AND buttons at the left of the rules:

Choose the rule operator OR AND

Rules have four parts:

  • a target
  • a property name or path
  • an invert operator toggle
  • a comparison operator
  • a value

1. Target#

Rule target

In the dropdown menu you can choose between:

  • the body value (full raw content or one of its properties if request's Content-Type is either application/json, application/x-www-form-urlencoded, multipart/form-data, application/xml, application/soap+xml or text/xml).
  • the value of a header.
  • the value of a cookie.
  • the value of a route parameter.
  • the value of a query string field.
  • the request number index starting at 1.

2. Property name or path#

Rule property

Depending on the target, the way to access properties may be different:

  • body:
    • keep empty to match against the full raw body content.
    • use a path to access one of its properties. The syntax is based on the object-path library like This is compatible with request's bodies of Content-Type application/json, application/x-www-form-urlencoded, multipart/form-data, application/xml, application/soap+xml or text/xml. Properties containing dots are supported by escaping the dots: key.key\.with\.dot.
      Please note that XML bodies are parsed using xml-js package. Refer to this page or the package documentation for more information on how the XML is parsed and how to fetch specific properties.
      Please also note that multipart/form-data only supports fields. Uploaded files will be ignored.
  • headers: a header name like Accept or Content-Type.
  • cookies: the cookie name like Session-id.
  • route param: a route param name without the colon (":"), :userId becoming userId.
  • query string: either provide a property name like filter or a path if the query string field is an object filter.primary.
  • request number: nothing has to be provided here for the request number.

For body and query string, if the property is an array, Mockoon will automatically check in the array if at least one item matches the value.

3. Invert operator#

You can invert the comparison operator (! equals, ! regex match, etc.) by toggling on the exclamation mark button:

Rule comparison operator

4. Comparison operator#

Rule comparison operator

Multiple comparison operators are available in each rule:

  • equals: asserts that the targeted property is equal to the value.
  • regex match: asserts that the targeted property matches the regex value.
  • null: asserts that the targeted property is null or absent (for headers or cookies).
  • empty array: asserts that the targeted property is an empty array.

5. Value#

Rule value

Depending on the comparison operator chosen, equals or regex match, you can either set a simple text value like "expected value" or any kind of regex. To use a regex, you must write it without the leading and trailing slashes.

Regex examples: primary|secondary, ^user1-9, UTF-.*.
You can also test for empty values with the following regex: ^$|\s+.

The request number supports simple entries like 1 or 2 but also regexes, allowing you to return a different response for the first 3 calls ^[1-3]$ or failing on odd request indexes [13579]$.

💡 The response rule values also support templating helpers to create dynamic rules. See the templating helpers documentation for more information.