Trillian is a transparent, cryptographically verifiable data store that implements a scalable Merkle tree architecture for append-only logs.
Trillian solves the problem of building large-scale, auditable data structures where clients can cryptographically verify that data has not been tampered with or selectively hidden. It implements a Merkle tree whose contents are served from a data storage layer, enabling scalability to extremely large trees. The core system provides an append-only Log mode that fills the Merkle tree densely from the left, analogous to Certificate Transparency logs. Applications build on top of Trillian's transparent data store by providing their own personalities, which are application-specific layers that define how the underlying transparency infrastructure is used.
Trillian is production-ready and deployed by multiple organizations at scale, particularly as the foundation for Certificate Transparency log operators. The codebase is stable and no new features are planned for this version. However, the project is in maintenance mode, and the README recommends that new log operators first evaluate Tessera, which implements the next generation of transparency logs using Tiled APIs. Trillian remains suitable for organizations operating existing transparency infrastructure or those specifically requiring its Merkle tree architecture. Building and running Trillian requires Go and either MySQL or MariaDB for the data storage layer.
Development activity on the project is minimal, with the maintainers explicitly stating they do not plan to add new features and will attempt to avoid incompatible changes, though they cannot guarantee this. Community contributions are still accepted, but contributors are encouraged to file issues and discuss proposals before beginning work. The codebase is stable enough for production use but is not actively evolving with new capabilities.
