Hi Product Hunt! I'm Byoungyoung from Mandu Security. Coding agents read your files as they work: .env, SSH keys, cloud logins. Once a key is read, it rides along in every request to the AI provider, and whatever the agent holds can go to any server a command names. The usual fix is to block the agent from reading .env. That keeps the key home, and the agent can't use it either. Mandu takes a different route. The AI gets a placeholder, like $MDU:nomodel_Read[9bbd].STRIPE_KEY, that it can pass around and put in a command. When that command goes to a host your rule allows, say api.stripe.com, Mandu fills in the real key on the way out. Anywhere else, the request waits on the dashboard for your OK. You still see the real values in the agent's replies. A few things we cared about: • No changes to your agent. Type `mandu claude` or `mandu codex` and you're running. It uses your agent's own login, Claude Pro and Max included. • Local only. No account, no Mandu server, no telemetry; everything stays in ~/.mandu. • No root. It runs as your user and adds kernel hardening (seccomp, Landlock) where your kernel allows. When it can't decide, it fails closed. • Open source, Apache-2.0, built on our research on agent security (DualView, arXiv:2607.03821). We measured it: 15 everyday tasks with a secret in them (file a bug report, debug a payment error, move a .env to a hosting platform, and more), 3 live runs each with Claude Code. Mandu kept the secret and finished the task in 43 of 44 runs, and in 41 of 45 on a fresh install with no setup. The next best setting managed 27 of 45. We chose the tasks and tuned Mandu on earlier runs of them, so weigh it accordingly; the method and every result are in the repo. What it doesn't do: with the default protection, Mandu does not defend against prompt injection. A web page can still steer the agent; Mandu guards where your secrets go. It's Linux first, and macOS is experimental. Two questions for you: which secrets does your agent sit next to that worry you most? And which agent should we support next?

Mandu

Keeps your secrets from your AI agent, and keeps it useful

Keeps your secrets from your AI agent, and keeps it useful