Best Agent Sandbox Tools in 2026: 10 Options Compared

Your AI coding agent has access to your terminal, your filesystem, your SSH keys, your AWS credentials, and your network. Right now. Most developers know this and do nothing about it because sandboxing used to mean "set up a VM and lose half your workflow."

That's no longer true. There are now 10+ purpose-built tools for sandboxing AI agents, ranging from a single shell script to a full Kubernetes cluster. Here is what each one does, what it costs you in complexity, and which one you should actually use.

TL;DR

Choose Membrane if you want the best balance of security and simplicity - Docker + eBPF monitoring, single command, no Kubernetes
Choose Agent Safehouse if you're on macOS and want zero-dependency kernel sandboxing in one command
Choose Docker Sandboxes if you need Docker-in-Docker capability inside the sandbox
Choose NVIDIA OpenShell if you need enterprise-grade policy enforcement and don't mind running Kubernetes
Choose E2B if you want cloud-hosted isolation with no local setup
Choose Bubblewrap if you want the lowest-level primitive with zero overhead

Quick Comparison

Tool	Setup	Isolation	Network Control	Agent-Aware	Platform	Overhead
Membrane	Single command	Docker + eBPF	DNS hostname allowlist	Agent-agnostic	Linux	Near-zero
Agent Safehouse	Single command	macOS Seatbelt	No	Yes (12+ agents)	macOS only	Zero
Anthropic srt	npm install	OS primitives	Domain allow/deny	Claude Code	macOS/Linux	Zero
Docker Sandboxes	Docker Desktop	Firecracker microVM	Allow/deny lists	Yes (6+ agents)	All	~125ms boot
NVIDIA OpenShell	Install + create	K3s in Docker	L7 YAML policies	Yes (5+ agents)	Linux	Heavy
E2B	API key + SDK	Firecracker cloud	Full VM isolation	Yes	Cloud	80ms boot
Daytona	API key + SDK	Containers	Container-level	Yes	Cloud/self-host	<90ms boot
Firejail	apt install	Namespaces + seccomp	Optional	No	Linux	Negligible
Bubblewrap	apt install	Namespaces	Namespace removal	No	Linux	Zero
gVisor	Install runsc	User-space kernel	Full interception	No	Linux	10-30% I/O

Membrane - Best Overall

Membrane does what OpenShell does without the Kubernetes. It wraps your agent in a Docker container with an eBPF sidecar (Tracee) that monitors every syscall at kernel level, plus a DNS-intercepting firewall that whitelists hostnames instead of IPs.

go install github.com/noperator/membrane/cmd/membrane@latest
cd /workspace && membrane

Two commands. Your agent runs inside a container with:

Network: DNS-based hostname allowlist. Only explicitly whitelisted domains resolve. Everything else is blocked. IPs refresh every 60 seconds to handle CDN rotation
Filesystem: Pattern-based file shadowing. Sensitive files (.env, .ssh/) are replaced with empty versions inside the container. Git-aware protection prevents agent modifications to .gitignore and repo metadata
Monitoring: eBPF traces every syscall the agent makes, captured as compressed JSONL for post-hoc analysis. You can replay exactly what the agent did
Config: Two-level YAML - global (~/.membrane/config.yaml) and per-workspace (.membrane.yaml). Supports env var expansion with shell command substitution blocked

The architecture is elegant: Docker for isolation, eBPF for visibility, DNS interception for network control. No Kubernetes. No hypervisor. No policy engine running as a separate service. The security primitives are the ones the Linux kernel already provides - Membrane just composes them into an agent-aware configuration.

Limitations: Experimental (v0.2.0). Single contributor. CDN IP rotation can break connections until the 60-second refresh. No HTTPS endpoint-level whitelisting (hostname only, not path). Docker-in-Docker on macOS not yet supported.

Verdict: The best tool for developers who want real isolation without architectural overhead. If you're comfortable with Docker and want to sandbox any agent with kernel-level monitoring, this is it.

Agent Safehouse - Best for macOS

Agent Safehouse is a single shell script (99.8% Bash) that creates macOS sandbox-exec profiles. Zero dependencies beyond Bash and macOS.

brew install eugene1g/safehouse/agent-safehouse

It has pre-built profiles for 12+ agents: Claude Code, Codex, OpenCode, Amp, Gemini CLI, Aider, Goose, Auggie, Pi, Cursor Agent, Cline, Kilo Code, and Droid. The sandbox uses a deny-first approach - everything is blocked, then you explicitly allow what the agent needs.

Smart HOME directory handling: the agent can traverse directory metadata (list files) but can't read file contents unless explicitly allowed. Auto-detects git worktrees. Includes a prompt you can give your agent to generate its own least-privilege profile.

Limitations: macOS only. No network isolation (filesystem only). A shell script, not a compiled binary.

Verdict: If you're on macOS, install this right now. It takes 30 seconds and immediately prevents your agent from reading your SSH keys, cloud credentials, and browser data.

Anthropic Sandbox Runtime (srt) - Best Native Integration

Anthropic's srt uses native OS primitives - macOS Seatbelt on Mac, Bubblewrap on Linux. No containers, no VMs. The lightest-weight option with real network control.

npm install -g @anthropic-ai/sandbox-runtime

Domain-level network allowlists and denylists. HTTP/HTTPS traffic routes through a proxy; other TCP through SOCKS5. Filesystem deny-then-allow with glob patterns on macOS. Anthropic reports 84% fewer permission prompts in Claude Code when using srt.

Limitations: Built for Claude Code. Windows not supported. Linux uses literal paths only (no globs).

Verdict: The official answer from Anthropic. If you use Claude Code and want the vendor-supported path, this is it.

Docker Sandboxes - Best Docker-in-Docker

Docker Sandboxes run Firecracker microVMs - each sandbox gets its own kernel and Docker daemon. This means agents can build and run Docker containers inside the sandbox while remaining isolated from your host.

Boot time is ~125ms with <5 MiB memory overhead. Native support for Claude Code, Gemini, Codex, Copilot, Kiro, and Agent. GA since January 2026.

Limitations: Requires Docker Desktop (commercial license). Not free for enterprises.

Verdict: The only option that gives agents Docker-in-Docker capability without compromising host isolation. If your agent needs to build containers, this is the only real choice.

NVIDIA OpenShell - Most Comprehensive, Most Complex

NVIDIA OpenShell is the enterprise answer. It runs a full K3s Kubernetes cluster inside Docker, with four components: Gateway, Sandbox, Policy Engine, and Privacy Router. YAML policies control filesystem, network, process, and inference routing. API keys are injected at runtime and never touch disk.

curl -LsSf https://raw.githubusercontent.com/NVIDIA/OpenShell/main/install.sh | sh
openshell sandbox create -- claude

The two-command setup is deceptively simple. Under the hood, you are running Kubernetes. That means Kubernetes-level debugging complexity, startup latency, and memory overhead. The policy engine is powerful - L7 filtering lets you allow GET but block POST to the same endpoint, and policies hot-reload without restarting the agent. But you are paying for that power with architectural weight.

Limitations: Alpha software, single-player mode. K3s overhead is significant for a single-agent sandbox. Enterprise partnerships (Adobe, Atlassian, Cisco) are announcements, not deployments.

Verdict: The right choice if you are building an enterprise platform that'll manage dozens of sandboxed agents with centralized policy enforcement. Overkill for a solo developer sandboxing one Claude Code instance. If Membrane gives you 90% of the security at 10% of the complexity, OpenShell gives you 100% of the security at 10x the complexity.

E2B - Best Cloud-Hosted

E2B provides cloud-hosted Firecracker microVMs with 80ms startup. Each sandbox is a full Linux VM. SDKs in Python and TypeScript. Built-in code interpreter. No local setup beyond an API key.

Limitations: Cloud-only for production. 24-hour session limit. Requires sending your code to E2B's infrastructure.

Verdict: Best for teams building agent platforms where the agent runs server-side, not on developer machines.

Daytona - Best for Persistent Workspaces

Daytona provides container-based sandboxes with sub-90ms startup and indefinite lifespans (no 24-hour limit like E2B). Built-in Git, LSP, and filesystem APIs. Self-hosting option via AGPL-3.0 license.

Verdict: Choose over E2B when you need persistent workspaces that survive between agent sessions.

The Low-Level Primitives

These aren't agent-specific tools. They're the building blocks that the agent-aware tools are built on.

Bubblewrap

The sandboxing primitive used by Claude Code (via srt) and Codex internally. Thin wrapper around Linux namespaces. Zero overhead. Maximum control. Minimum convenience.

bwrap --ro-bind /usr /usr --dev /dev --proc /proc \
  --bind /workspace /workspace --unshare-net -- claude

Firejail

900+ pre-built application profiles. More user-friendly than Bubblewrap with seccomp-bpf, AppArmor integration, and capability dropping. firejail --net=none claude-code is the fastest path to basic isolation on Linux.

gVisor

Google's user-space application kernel. Intercepts every syscall in memory-safe Go code. 10-30% I/O overhead. The strongest isolation short of a full VM, used by Northflank for 2M+ workloads/month.

Decision Matrix

Your Situation	Recommended Tool
Solo dev, want simplicity + real security	Membrane
macOS user, want it done in 30 seconds	Agent Safehouse
Claude Code user, want vendor support	Anthropic srt
Agent needs to run Docker inside sandbox	Docker Sandboxes
Enterprise, managing many agents	NVIDIA OpenShell
Building an agent platform (server-side)	E2B or Daytona
Linux, want lowest-level control	Bubblewrap or Firejail
Maximum isolation, performance tradeoff OK	gVisor

The agent sandboxing space went from "nonexistent" to "ten competing tools" in under six months. That's how fast the industry recognized that letting AI agents run unsandboxed on developer machines was a liability. The tools range from a 99-line shell script to a full Kubernetes cluster. The right choice depends on how much complexity you're willing to accept for how much security you need. For most developers, the answer is Membrane: real isolation, real monitoring, no Kubernetes, one command.

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