Ben Birt

I'm a software engineer in London. I've spent over fifteen years building infrastructure, mostly at Google, with a spell in between as head of engineering at Dataform, a data engineering startup acquired by Google Cloud in 2020. I now work on privacy engineering at Google DeepMind.

I'm most interested in systems that enforce transparency, reproducibility and hermeticity: systems that don't need implicit trust, but whose claims are falsifiable.

ben@benbirt.io · GitHub · LinkedIn

Transparency

Private AI Compute transparency log

I designed and launched the binary transparency log behind Google's Private AI Compute, including its use of third-party witnesses. The log and witnesses conform to C2SP specifications such as tlog-tiles and tlog-witness. I also contribute to C2SP and wrote tlog-list.

I delivered a talk at the 2026 transparency.dev summit, covering Google's transparency log witnessing programme.

git-ratchet

git-ratchet enforces forward-only protection for Git branches and immutability for tags. The repository contains a transparency log mapping branches and tags to commits, so rewritten history cannot be hidden from a downstream verifier.

I delivered a talk on it at the 2026 transparency.dev summit (slides).

• Code

git-witness

A witness for git-ratchet logs. It uses the standard C2SP tlog-witness protocol, with GitHub issues as the underlying HTTP transport.

• Code

tlog-viewer

A static transparency log viewer which performs cryptographic verification in the browser.

• Open it
• Code

Reproducible builds

rules_tofu

Bazel rules for OpenTofu. Configuration becomes ordinary build targets: bazel build validates it, bazel test runs tofu test, and bazel run plans and applies it. Bazel pins and fetches providers and the tofu binary.

• Code
• Bazel Central Registry

song-of-time

A fully reproducible Nix configuration for my NixOS and macOS machines. It includes home-grown tools, such as automated deployment of configuration pulled directly from GitHub, with health checks.

• Private for now

Data tooling

Dataform

An open-source framework for managing SQL data pipelines in BigQuery. I led engineering at the startup and continued as technical lead after Google Cloud acquired it.

• Code

Other

Eavesbard

Hands-off ambient music for tabletop role-playing sessions.

• Open it
• Code

The Hollow Isle

A top-down action game that runs in the browser, inspired by my love of the Zelda series.

• Play it
• Code