nsjail alternatives
The 5 alternatives below are grouped by kind of sandbox, and each says what it does differently from nsjail. Start from whatever made you look: missing GPUs, session limits, self-hosting, pricing or isolation.
Why teams look beyond nsjail
A strong OS-level jail for execution APIs and CTF-style workloads; pair it with a VM when you need a kernel boundary.
- Shares the host kernel; a kernel bug reachable through the allowed syscalls escapes the jail
- Linux only, and several features require root or enabled user namespaces
- No snapshots, persistence or orchestration API
- Release cadence is irregular and a recent release shipped a seccomp regression
nsjail alternatives, by kind
Code execution APIs
Submit code, get output: online judges, compiler APIs and Jupyter kernels as a service.
Judge0
Open-source online code execution system (GPL-3.0) that runs each submission in an isolate sandbox, offered as Judge0 Cloud via RapidAPI or directly and as a self-hosted Docker Compose stack.
- isolate (namespaces/cgroups)
- Open source
- Self-hostable
How it differs: Batch "submit code, get stdout" judging in 60-90+ languages with per-submission CPU, wall-clock and memory limits. The reference open-source online judge: ideal for stateless, time-boxed code evaluation at scale, but not a workspace an agent can return to.
Piston
MIT-licensed code execution engine that runs each submission in an isolate sandbox inside a Docker container, with a public API at emkc.org restricted to approved non-commercial projects since February 2026.
- isolate in Docker
- Open source
- Self-hostable
How it differs: Self-hosted, stateless execution of untrusted snippets in 80+ languages with isolate-level sandboxing. A solid self-hosted judge engine for stateless snippet execution; treat the public emkc.org API as unavailable for commercial agents.
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.
Firejail
A SUID Linux sandbox that confines desktop and server applications with namespaces, seccomp-bpf and capabilities, shipping around 1,350 application profiles.
- Namespaces + seccomp
- Open source
- Self-hostable
How it differs: Confining a browser or desktop application on a Linux workstation with ready-made profiles. The convenient choice for confining desktop applications on a Linux laptop; not designed as a server-side sandbox primitive.
gVisor
Google's user-space application kernel for containers, with the runsc OCI runtime, GPU passthrough via nvproxy and checkpoint/restore; used by Modal, Beam, Anthropic, OpenAI and Google Cloud.
- User-space kernel
- Open source
- Self-hostable
- GPU
- Snapshots
How it differs: Sandboxing containers on hosts where you cannot or do not want to run a VM per workload, including GPU workloads. The most widely adopted non-VM sandbox boundary; choose it when a VM per workload is impractical or you need sandboxed GPUs.
nsjail vs alternatives
| Sandbox | Isolation | Open source | Self-host / BYOC | Cold start (vendor) | Max session | Snapshots / pause | GPU | SDKs |
|---|---|---|---|---|---|---|---|---|
| nsjail | Namespaces + seccomp | Yes | Yes / No | Not documented | Configurable | No / No | Not documented | CLI |
| bubblewrap | Linux namespaces | Yes | Yes / No | Not documented | Not documented | No / No | Not documented | CLI |
| Firejail | Namespaces + seccomp | Yes | Yes / No | Not documented | Not documented | No / No | Not documented | CLI |
| gVisor | User-space kernel | Yes | Yes / No | ms (claim) | Not documented | Yes / Not documented | Yes | CLI |
| Judge0 | isolate (namespaces/cgroups) | Yes | Yes / No | Not documented | 5 s wall (max 20 s) | No / No | No | REST API, Python, JavaScript/TypeScript |
| Piston | isolate in Docker | Yes | Yes / No | Not documented | 3 s run / 10 s compile | No / No | No | REST API |
Frequently asked questions
What are the main alternatives to nsjail?
Is there an open-source alternative to nsjail?
Cite this page
Agent Sandboxes. (2026). nsjail alternatives. agentsandboxes.org. Last reviewed November 9, 2026. https://agentsandboxes.org/alternatives/nsjail/
Found an error or a missing sandbox? Submit a correction — every entry links to the sources it relies on.