How to Use Global Variables in Postman for API Testing

In Postman, you use pm.globals.set('variableName', 'value') to create or update a global variable and pm.globals.get('variableName') to access its value. Global variables are accessible across all requests and collections within your Postman workspace.

Syntax

Postman provides simple commands to work with global variables:

• pm.globals.set('variableName', 'value'): Creates or updates a global variable.
• pm.globals.get('variableName'): Retrieves the value of a global variable.
• pm.globals.unset('variableName'): Deletes a global variable.
• pm.globals.clear(): Removes all global variables.

Use these commands inside the Pre-request Script or Tests tabs of your requests.

javascript

pm.globals.set('token', '12345abcde');
const tokenValue = pm.globals.get('token');
console.log(tokenValue);

Output

12345abcde

Example

This example shows how to save a token from a login response as a global variable and then use it in another request's header.

javascript

// In the Tests tab of the login request
const jsonData = pm.response.json();
pm.globals.set('authToken', jsonData.token);

// In the Headers tab of another request
// Key: Authorization
// Value: Bearer {{authToken}}

Output

If login response contains {"token": "abc123"}, the global variable 'authToken' is set to 'abc123'. Subsequent requests use it in the Authorization header.

Common Pitfalls

• Forgetting to set the variable: If you try to use a global variable that was never set, it will be undefined.
• Scope confusion: Global variables override environment variables with the same name, which can cause unexpected values.
• Not clearing old variables: Old global variables persist until manually cleared, which can cause stale data issues.

Always check if the variable exists before using it and clear unused globals regularly.

javascript

/* Wrong way: Using a global variable without setting it first */
const token = pm.globals.get('missingToken');
console.log(token); // undefined

/* Right way: Check before use */
if(pm.globals.has('authToken')) {
  const token = pm.globals.get('authToken');
  console.log(token);
} else {
  console.log('authToken is not set');
}

Output

undefined
authToken is not set

Quick Reference

Command	Description	Example
pm.globals.set('key', 'value')	Create or update a global variable	pm.globals.set('userId', '123')
pm.globals.get('key')	Get the value of a global variable	const id = pm.globals.get('userId')
pm.globals.unset('key')	Delete a global variable	pm.globals.unset('userId')
pm.globals.clear()	Remove all global variables	pm.globals.clear()

Key Takeaways

Use pm.globals.set() to create or update global variables accessible across all requests.

Access global variables with pm.globals.get() inside scripts or use {{variableName}} in request fields.

Always verify a global variable exists before using it to avoid undefined errors.

Clear unused global variables regularly to prevent stale data issues.

Global variables override environment variables with the same name, so manage scopes carefully.