Butter
W25Muscle Memory Cache for Agents
Embedded Sandboxes for Agents
Butter is building an LLM proxy that records and deterministically replays tool call trajectories. Our goal is to get LLMs out of the hotpath for repetitive tasks, increasing speed, reducing variability, and eliminating token costs for the many cases that could have just been a script.
Butter is building bVisor, an incredibly lightweight sandbox runtime for AI agents. It embeds directly into your local process, providing a safe bash environment without the overhead of VMs or remote infra.
The company shifted from building an LLM proxy for recording and replaying agent tool calls to offering a lightweight, local sandbox runtime for agents. The new product focuses on embedded process isolation rather than LLM tool call management, representing a meaningful product pivot within the AI agent space.