Codex CLI sandboxing alternatives
The 6 alternatives below are grouped by kind of sandbox, and each says what it does differently from Codex CLI sandboxing. Start from whatever made you look: missing GPUs, session limits, self-hosting, pricing or isolation.
Why teams look beyond Codex CLI sandboxing
Solid built-in confinement for Codex CLI across all three desktop platforms; it is a CLI feature, not a reusable sandbox.
- OS-level sandboxing shares the host kernel; full-access mode removes all boundaries
- Linux requires bubblewrap and user-namespace support; Windows mxc needs specific recent builds
- Windows unelevated mode has weaker network isolation and no denied read paths
Codex CLI sandboxing alternatives, by kind
Isolation primitives and runtimes
The hypervisors, user-space kernels, OS sandboxes and WebAssembly runtimes that sandbox platforms build on.
bubblewrap
The unprivileged Linux namespace sandboxer behind Flatpak and Anthropic's sandbox runtime; you assemble the policy from command-line flags.
- Linux namespaces
- Open source
- Self-hostable
How it differs: Lightweight process sandboxing on Linux where you control the policy and do not need a kernel boundary. The right primitive for a laptop or CI sandbox on Linux when you can write the policy yourself; not a substitute for a VM.
Local sandboxes for coding agents
Isolation for agents like Claude Code, Codex or Gemini CLI on your own laptop.
Anthropic Sandbox Runtime
Open-source CLI and library (`srt`) that restricts filesystem and network access for any local process at the OS level, without a container or VM.
- OS-level (Seatbelt / bubblewrap)
- Open source
- Self-hostable
How it differs: Lightweight local sandboxing of coding agents and CLI tools. Excellent lightweight guardrail for local agents; pair with a VM for untrusted multi-tenant code.
Gemini CLI sandboxing
Gemini CLI's built-in sandbox: macOS Seatbelt profiles or a Docker/Podman container around the agent's tool calls, with gVisor, LXC and a Windows option.
- Seatbelt or container
- Open source
How it differs: Confining Gemini CLI tool execution on a developer machine using built-in OS or container sandboxing. Adequate built-in confinement for Gemini CLI users; it is a feature of the CLI rather than a general sandbox.
Minimal
Open-source CLI that runs coding agents in declarative, isolated sessions built from a minimal.toml and a from-source package catalogue, on Linux namespaces or a libkrun microVM.
- namespaces or libkrun microVM
- Open source
How it differs: Reproducible, declaratively scoped local sessions for Claude Code, Codex, Gemini and Pi with a supply-chain-audited toolchain. A promising beta for developers who want declarative, reproducible agent sessions and are comfortable with a young toolchain.
nono
Kernel-enforced OS-native sandbox for coding agents that runs each tool call in its own ephemeral sandbox, brokers credentials and keeps a tamper-evident audit chain.
- Landlock / Seatbelt
- Open source
- Snapshots
How it differs: Running Claude Code, Codex and other coding agents on your own machine with kernel-enforced file and network allow-lists and brokered credentials. A strong choice for per-tool-call policy and credential brokering around local coding agents, provided OS-level isolation is enough for your threat model.
Windows Sandbox
Disposable Windows desktop built into Windows Pro, Enterprise and Education, running on the Microsoft hypervisor with a separate kernel and wiped on close.
- Hyper-V lightweight VM
- GPU
How it differs: Running an untrusted Windows application or a Windows-targeting coding agent on a disposable copy of the host OS. A free, well-isolated throwaway Windows desktop for single-agent or manual use, not a platform for running agents at scale.
Codex CLI sandboxing vs alternatives
| Sandbox | Isolation | Open source | Self-host / BYOC | Cold start (vendor) | Max session | Snapshots / pause | GPU | SDKs |
|---|---|---|---|---|---|---|---|---|
| Codex CLI sandboxing | Seatbelt / bubblewrap / Windows | Yes | No / No | Not documented | Not documented | No / Not documented | Not documented | CLI |
| Anthropic Sandbox Runtime | OS-level (Seatbelt / bubblewrap) | Yes | Yes / Not documented | Process start | Not documented | No / No | Not documented | CLI (srt), TypeScript (npm) |
| bubblewrap | Linux namespaces | Yes | Yes / No | Not documented | Not documented | No / No | Not documented | CLI |
| Gemini CLI sandboxing | Seatbelt or container | Yes | No / No | Not documented | Not documented | No / Not documented | Not documented | CLI |
| Minimal | namespaces or libkrun microVM | Yes | No / No | Not documented | Not documented | Not documented / Not documented | Not documented | CLI, MCP server |
| nono | Landlock / Seatbelt | Yes | No / No | Not documented | Not documented | Yes / Not documented | Not documented | CLI, Rust, Python, JavaScript/TypeScript, Go |
| Windows Sandbox | Hyper-V lightweight VM | No | No / No | A few seconds | Until closed | No / No | Yes | CLI |
Frequently asked questions
What are the main alternatives to Codex CLI sandboxing?
Is there an open-source alternative to Codex CLI sandboxing?
Cite this page
Agent Sandboxes. (2026). Codex CLI sandboxing alternatives. agentsandboxes.org. Last reviewed November 9, 2026. https://agentsandboxes.org/alternatives/codex-cli-sandbox/
Found an error or a missing sandbox? Submit a correction — every entry links to the sources it relies on.