Making YAML the Default in Bruno v3.1

Overview

As you know, Bruno stores collections directly on your filesystem, with each request saved in a plain-text .bru format.

If you already have collections in the .bru format, nothing will break. We will continue to maintain full feature parity, and both formats will remain fully supported.

Key Differences

Category	BRU	YAML
Performance	Parsing time increases sharply as collection size grows; slow loading with larger files	Consistent and predictable parsing performance; scales and handles large collections efficiently
Tooling & Editor Support	Limited to Bruno-specific extension; no native linting, formatting, or schema validation in standard editors	Native support in most editors; rich ecosystem including yamllint, Prettier, JSON Schema validation, structural diffs
AI & Ecosystem Compatibility	Custom proprietary syntax; limited external understanding outside Bruno	Industry-standard format; widely understood by AI tools, CI pipelines, and developer tooling

Why we're making this change?

When we introduced the BRU format, the goal was to support both GUI-first and CLI workflows while keeping collections plain text and Git-friendly.

Two years later, we've learned that most users primarily use Bruno as a GUI tool, and maintaining a custom syntax alongside a growing feature set has become increasingly difficult.

Tooling has also been a consistent concern. As a custom format, BRU doesn't benefit from the broader ecosystem; no native editor support, standard linting, schema tooling, or strong AI understanding.

So we evaluated alternatives. While TOML works well for small configs, API collections often involve deeply nested structures and arrays; which YAML handles more naturally. Read more about it here.

Migration

Today, you can migrate via exporting and re-importing. In future versions, we will provide a better way to automatically migrate. Migration to YAML is completely lossless.

Performance improvements

In our benchmarks, YAML parsing is 4-5x faster than BRU and scales significantly better with large collections.

Request Loading (0.1–2 MB)

Collection Loading (1–10 MB)

OpenCollection: A Standard for API Collections

As part of this release, we're also excited to introduce a new specification we've been working on: OpenCollection.

YAML in Bruno is powered by Opencollection, a developer first open specification for defining and sharing API collections. Bruno now uses this format to store your collections.

• Website: https://www.opencollection.com
• Schema Explorer: https://schema.opencollection.com/
• GitHub: https://github.com/opencollection-dev/opencollection

Conclusion

We're excited about this next chapter for Bruno. YAML gives us a solid foundation to build on; better tooling, faster performance, and a format that developers already know and trust. We're looking forward to seeing what you build with it.

If you have any feedback with YAML migration or have some questions or comments, please share them here.