Claude Fable 5.1, together with its immediate predecessor, has been one of the biggest unlocks behind the Yoetz we’re launching today. We’ve been experimenting with versions of Yoetz for a long time. But the decision to make the real pivot into what Yoetz is now, a system built around agent orchestration, verification, and making AI work more reliably, became possible much faster because of what the Fable generation unlocked for us. Fable 5 was the moment where a lot of ideas that had previously felt ambitious suddenly became practical. Fable 5.1 pushed that even further. Its ability to reason across large codebases, handle long-running engineering tasks, coordinate complex changes, and stay useful deep into an implementation has genuinely changed the speed at which we can build. Alongside its strongest competitor, which we also shouted out, this generation of models has been the real technical unlock for Yoetz. We could iterate on the architecture, test much more ambitious ideas, and turn what had existed in different forms for a long time into the product we actually wanted to build. That is why this shoutout feels especially important to us. Fable did not just help us write code faster. It helped make this version of Yoetz possible. Thank you to the Claude team for pushing the frontier far enough that ideas like ours can actually be built.

OpenAI has been foundational to how we built Yoetz. Codex CLI being open source was especially important. Being able to understand and build directly around the agent harness helped us create the original Yoetz v0.1, and Codex remains one of the main environments we build and test Yoetz against today. ChatGPT has become part of our everyday workflow across engineering, research, product, and everything in between, while OpenAI’s APIs and developer tooling have made it remarkably easy to build on top of their ecosystem. Most recently, GPT-6 Astra has been a major accelerator for us. Its coding, long-horizon work, and orchestration capabilities pair incredibly well with Yoetz’s verification system, helping us build faster while still checking that the work actually holds up. OpenAI isn’t the only AI ecosystem we use, which is exactly why this shoutout matters. Across models, open-source developer tools, APIs, Codex, ChatGPT, and Work, they’ve consistently given us tools we genuinely want to build with. If you’re building tools around AI agents, I especially recommend exploring Codex CLI. Having an open-source agent harness you can inspect, extend, and build integrations around is incredibly powerful. Thank you to the OpenAI team for building not just great models, but an ecosystem developers can actually build on.

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Products used by Yoetz

Explore the tech stack and tools that power Yoetz. See what products Yoetz uses for development, design, marketing, analytics, and more.