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Overview

Runtime variables are ephemeral variables that exist only during the runtime of the API client. These variables are scoped within a collection, meaning they are accessible to all requests within that collection. However, once the API client is closed or restarted, the values of these variables are lost. They are ideal for managing temporary data such as session tokens, dynamic parameters, or other values that are generated or updated during the execution of requests.

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Creating a Runtime Variable

To create a runtime variable, you can use the bru.setVar(name, value) function. This function allows you to store any value (e.g., tokens, response data, temporary user inputs) as a runtime variable.

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Example:

Suppose you receive an authentication token as part of a response body and want to reuse it in subsequent requests. You can capture it using the bru.setVar() function in your post response script.
Runtime variables table with nested JSON values

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Using a Runtime Variable

Once a runtime variable is created, you can use it in subsequent API requests by referencing it with the {{variableName}}syntax. The variable’s value will be dynamically injected into the request at runtime.

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Example:

If you’ve stored a token variable using bru.setVar(), you can use it in headers, query parameters, body, or URL of subsequent requests like this:
You can also use the bru.getVar() function to get the value of a runtime variable and use it inside your pre request scripts.

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Viewing Runtime Variables

  1. Click on the (…) icon in the top-right of the corner.
  2. Select Variables from the dropdown.
It will open the variables tab with a table with all the runtime and environment variables.
The request must be executed before you can view the runtime variables.
Example: Consider the following script inside Bruno, which creates a runtime variable. Nested objects show up in the same table as environment variables:
Once the request is executed, the runtime variable is available in the variables view: Runtime variables table with nested JSON values The variables table matches the requests and environments tables.

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Expand and collapse nested values

Objects and arrays expand in place. Bruno keeps that expand/collapse state for the session, keyed by variable path.

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Copy a value

Hover a row and click the copy icon. You do not need to select text.
  • Primitives (strings, numbers, booleans) copy as-is.
  • Objects and arrays copy as pretty-printed JSON, including when the node is collapsed.
  • Copy works for large values without freezing the UI.
  • Bruno shows a brief confirmation after a successful copy.