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Variable interpolation in Bruno allows you to use variables in your requests using the {{variableName}} syntax. Let’s explore how interpolation works with different data types.

Basic Interpolation

Strings

Numbers

Booleans

Referencing variables inside other variables

Interpolation is recursive: if a variable’s value contains another {{...}} placeholder, Bruno resolves the inner reference too. This lets you compose one variable from others directly in the Vars editor, without a pre-request script.
The same works for values entered as environment, collection, or folder variables in the UI. Bruno keeps resolving until every placeholder is replaced or an unknown variable is left in place. Cycles (for example, a{{b}} and b{{a}}) are detected and the last unresolved placeholder is left as-is.

Object Interpolation

Object interpolation is available from Bruno v2.2.0 onwards.
You can access object properties using dot notation. Here’s how to work with objects containing different data types:

Array Interpolation

Array interpolation is available from Bruno v2.2.0 onwards.

Date Interpolation

Practical Examples

API Authentication

Dynamic Query Parameters

Request Body with Mixed Types

Remember that variables set using bru.setVar() are available throughout your collection’s scope. Use them to make your requests more dynamic and maintainable.