Variable substitution in outbound REST messages

concept australia Updated Sep 10, 2026 1 min read c_VariableSubstitutionREST.md

You can use variables when creating outbound REST messages and assign values to those variables when performing a request.

Variables are allowed in the Endpoint URL, HTTP Header and HTTP Query Parameter Value fields, and the Content field for POST and PUT methods.

The syntax for variables is ${variable_name}. The REST message substitutes this variable with the parameter values provided when the method runs. For example, if the REST message Endpoint is http://myserver.mycompany.com/offices/${id}, a parameter named id must exist and contain a value that can be used when the method runs.

You can assign a value to variables when running the request using the RESTMessageV2 API setStringParameter and setStringParameterNoEscape methods.

When testing an HTTP method that includes variables, the Test value for each variable in the Variable Substitutions related list is used.

Generate REST message variables
Populate the list of variable substitutions automatically based on variables defined in several REST message HTTP method fields.

Parent Topic:Outbound REST web service

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---
title: Variable substitution in outbound REST messages
description: You can use variables when creating outbound REST messages and assign values to those variables when performing a request.
locale: en-US
canonical_url: https://www.servicenow.com/docs/r/australia/api-reference/web-services/c\_VariableSubstitutionREST.html
release: australia
product: Web Services
classification: web-services
topic_type: concept
last_updated: "2026-09-10"
reading_time_minutes: 1
breadcrumb: [REST, Outbound, Web services, API implementation, API implementation and reference]
---

# Variable substitution in outbound REST messages

You can use variables when creating outbound REST messages and assign values to those variables when performing a request.

Variables are allowed in the **Endpoint** URL, HTTP Header and HTTP Query Parameter **Value** fields, and the **Content** field for POST and PUT methods.

The syntax for variables is *$\{variable\_name\}*. The REST message substitutes this variable with the parameter values provided when the method runs. For example, if the REST message **Endpoint** is `http://myserver.mycompany.com/offices/${id}`, a parameter named **id** must exist and contain a value that can be used when the method runs.

You can assign a value to variables when running the request using the RESTMessageV2 API setStringParameter and setStringParameterNoEscape methods.

When testing an HTTP method that includes variables, the **Test value** for each variable in the **Variable Substitutions** related list is used.

-   **[Generate REST message variables](https://raw.githubusercontent.com/ServiceNow/ServiceNowDocs/australia/markdown/australia/api-reference/web-services/t_GenerateMessageVariables.md)**  
Populate the list of variable substitutions automatically based on variables defined in several REST message HTTP method fields.

**Parent Topic:**[Outbound REST web service](https://raw.githubusercontent.com/ServiceNow/ServiceNowDocs/australia/markdown/australia/api-reference/web-services/c_OutboundRESTWebService.md)