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Dev tools · May 13, 2026

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Mistle – Open-source infrastructure for running sandboxed coding agents

Hi HN, I'm Jonathan. My co-founder, Thomas, and I started building Mistle in Feb. We saw larger tech companies like Ramp (Inspect) and Stripe (Minions) build this internally and thought an open source version should exist. We made a few very intentional decisions when working on this: 1. Credentials are kept out of the sandbox. Authorized access goes through a proxy, so agents do not directly receive credentials. 2. The harness is not our problem. We're not going to tackle things like memory, self-learning. 3. No magic. Configurations are explicit. You can bring your own keys for models,…

What it does

In the maker’s words, at launch

Hi HN, I'm Jonathan. My co-founder, Thomas, and I started building Mistle in Feb. We saw larger tech companies like Ramp (Inspect) and Stripe (Minions) build this internally and thought an open source version should exist. We made a few very intentional decisions when working on this: 1. Credentials are kept out of the sandbox. Authorized access goes through a proxy, so agents do not directly receive credentials. 2. The harness is not our problem. We're not going to tackle things like memory, self-learning. 3. No magic. Configurations are explicit. You can bring your own keys for models, sandboxes, and other providers. You can write your own instructions and agent. Mistle can be run locally with a single command: https://github.com/mistlehq/mistle#run-mistle-locally Questions, feedback and ideas are welcome!

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