Boundary

Boundary is the company behind BAML, a programming language designed for writing AI agents and the code they produce. The name stands for Basically a Made up Language. It reads like TypeScript, with unions, generics, lambdas and pattern matching, but removes the escape hatches an agent could hide behind: there is no any type, no unchecked cast, and invalid states do not compile. Calling a model is a typed function: developers declare input and output types and get structured data back, with malformed model output repaired against the schema. It is aimed at engineering teams building LLM features and agent workflows who want correctness, testing and observability built into the language. Every function is traced and profiled locally rather than sampled, and Boundary says its tracing is six times faster than OpenTelemetry in Rust and 200 times faster in Python with far smaller traces. AI functions support streaming, batching, websockets, voice and any model provider. Workflow primitives cover concurrency, retries, cancellation and sandboxing, and tests can be generated from data or production traces, with flaky AI functions graded over many runs. BAML runs standalone on macOS, Linux and Windows or inside existing projects in Python, TypeScript for Node and the web, Java, C#, .NET, C++, Go, Rust, Kotlin for Android and Swift for iOS, with PHP and Ruby listed as coming soon. BAML is free and open source. It runs entirely on the developer's machine and never calls Boundary's servers. A paid cloud offering with observability, team controls and governance is announced as coming later this year, with no pricing published yet.