# Use variables and validations in sequences

Let's work with **variables** and **validations** inside a **Go** sequence. These tools let you parameterize values, generate dynamic inputs, and add checks that verify system behaviour during a load test.

## Replace a hard-coded value with a variable

To begin, identify the part of your script where you want to replace a **hard-coded value** with a **variable**. In this example, the goal is to parameterize a file name by replacing the static number with a value generated at runtime.

Click the line where the variable will be used. Before editing it, create a random value generator by inserting a **randomizer** . Choose the option to **generate a random number** and set the **range** by double-clicking the starting value. The generated number will be stored in a variable.

With the variable created, return to the line you want to modify. The **URL field** displays the resource that **Go** is fetching. Delete the hard-coded number and **right-click**. The variable you created appears in the context menu. Select it to insert the variable into the URL.

Press **Enter** to confirm the change. The line previously containing the fixed value now uses the variable, meaning that each execution of this sequence will fetch a resource determined by the variable. This is a practical example of how to make script steps dynamic rather than static.

## Add active validations

Go also allows you to add **active validations**. For any step in the sequence, you can open the details and specify what type of content it represents. You can then right-click to add a validation to the response header. This inserts a formatted assertion directly into the script. The assertion becomes part of the execution flow and verifies that the resource matches the expected type or value.

## Benefits of using variables and validations

These techniques help you make sequences:

* More **realistic**  
* More **flexible**  
* More **precise**

Variables introduce **variation** into the requests, while validations help ensure that the system responds **correctly** during performance testing.