Opencollection is an modern, developer-first specification pioneered by Bruno for defining and sharing API collections.
This has been one of the top asks by the community.
As explained here, one of the key reasons for introducing a new DSL was to support both GUI-first users and those who prefer working entirely from the CLI.
However, after two years of real-world usage, the data is clear: most people use Bruno primarily as a GUI, and value the fact that everything is stored as plain text files that can be easily version-controlled.
Another important learning was that while a custom syntax works well for simple use cases, it quickly becomes difficult to maintain as the schema grows in complexity - especially when building an API client meant for a global audience. This has been a consistent challenge over the past two years, and one of the most common pieces of feedback we’ve received is the lack of tooling around the existing DSL.
That left us with two options: YAML and TOML.
TOML works well for small configurations, but becomes hard to manage with deeply nested structures and arrays. As a result, we chose YAML.
OpenCollection is the result of everything we’ve learned so far. Since tooling for exploring complex schemas is limited, we built a visual schema explorer in-house to make the format easier to understand and adopt. Support for creating collections with OpenCollection format will ship with Bruno v3.0.0 schedule to go out on Jan 5th 2026
If the community response is positive, we plan to make OpenCollection the default format going forward. At the same time, we will continue to maintain feature parity between OpenCollection (YAML) and the existing Bru DSL, so existing collections remain fully supported.
Given the number of folks who already have Bru DSL based collections, We plan to maintain parity in the product for both YAML and Bru DSL
Website: https://www.opencollection.com
Schema Explorer: https://schema.opencollection.com/
Github repo: https://github.com/opencollection-dev/opencollection