Modal Sandbox Alternatives for AI Agents

The main Modal Sandboxes alternatives are Beam, E2B, Daytona and Vercel Sandbox, plus self-hosted runtimes for teams that want to run their own. Most teams start looking for one of three reasons: Modal caps every sandbox at 24 hours, GPU sandboxes can't run Docker or take memory snapshots, and sandboxes bill at three times Modal's list compute rate.

What Modal Sandboxes do well, and where they stop

Modal Sandboxes are containers you create from code to run untrusted or agent-written programs, on the same platform as Modal's functions and GPUs. They are a strong fit for teams already on Modal. The limits show up when an agent needs long sessions, Docker and a GPU together, or a memory snapshot it can fork.

What Modal does well:

• Three SDKs. Sandboxes can be driven from Python, JavaScript and Go.
• Two runtimes. gVisor is the default for most workloads, and a VM runtime with its own Linux kernel handles workloads that expect a full Linux machine, such as Docker, FUSE and nested cgroups.
• A wide GPU catalog. The same account that runs your sandboxes runs T4 through B200 GPUs.
• Filesystem and directory snapshots. Both are saved as images and kept for 30 days by default.
• Free monthly credits. The Starter plan has no platform fee and includes $30 of compute each month.

Where it stops:

• 24-hour maximum. Sandboxes default to a 5-minute lifetime, and the timeout can go up to 24 hours. Modal suggests restoring from a filesystem snapshot to run longer.
• GPU or Docker, not both. GPU sandboxes run only on gVisor, and Docker runs only on the VM runtime.
• Memory snapshots are in alpha. They expire after 7 days, can't be used with GPUs, have to restore on the same instance type, and snapshotting a sandbox terminates it.
• The 3x rate. Sandboxes bill at Modal's non-preemptible rate, three times list price: $0.00003942 per physical core per second and $0.00000667 per GiB per second. Modal bills the higher of what you request and what you use.

Our breakdown of Modal's pricing covers the plans and GPU rates in more detail.

Modal Sandboxes alternatives compared

Beam, E2B, Daytona and Vercel Sandbox all create sandboxes from an SDK, and they split on isolation, GPUs, memory snapshots and session length. E2B and Daytona have the lowest per-hour sandbox rates, Beam VMs are the cheapest option for a machine that stays up, and Beam and Daytona are the two that offer both GPUs and Docker. The table prices one sandbox with 1 vCPU and 2 GiB of memory for an hour at each vendor's list rate.

A few notes on reading it. Modal and Beam sandboxes bill per physical core, which equals 2 vCPU, so their figures are normalized to 1 vCPU. Vercel charges CPU only while the code is using it and counts memory in GB, so an agent that spends most of its time waiting on a model costs well under the full-CPU figure of about $0.17. Daytona lists its GPUs as preemptible.

How memory snapshots and forking compare

A memory snapshot saves the running processes along with the filesystem, so a forked sandbox picks up mid-task instead of rebooting and reinstalling. That's what lets an agent set up an environment once and then try five fixes in parallel. Platforms differ a lot here, and the ranking comparison pages mostly skip it.

What each one keeps:

• Modal: memory snapshots exist but are in alpha. Snapshotting terminates the source sandbox, the snapshot lasts 7 days, it can't be used on a GPU sandbox, and background processes started through exec aren't restored.
• Beam sandboxes: snapshot_memory() captures process state and the filesystem on supported runtimes, and create_from_memory_snapshot() restores it. Each fork gets its own identity and URLs.
• Beam VMs: pause checkpoints RAM and running processes, and resume restores them. Forks and snapshots copy the disk only.
• E2B: every sandbox is a Firecracker microVM, and pause, snapshots and fork all keep memory.
• Daytona: memory pause and fork need one of its VM classes. Container sandboxes don't have them.
• Vercel Sandbox: stopping a persistent sandbox snapshots its filesystem, and the next call resumes from it. Running processes aren't part of that snapshot.

Here's the fork pattern on a Beam sandbox, taken from Beam's sandbox quickstart. It starts a web server, snapshots memory with the server still running, and forks three copies that each serve their own URL:

Preview URLs on Beam sandboxes are public, so put authentication in the app before serving anything sensitive. For a wider look at which state each provider keeps, see our stateful sandbox comparison.

Running agents for longer than 24 hours

Modal, E2B Pro and Vercel all stop a session at 24 hours, so an agent that works through a long task needs to save state and restart somewhere. The way around it is a sandbox with no lifetime cap, or a persistent VM. Beam has both.

How each platform handles long runs:

• Modal: 24 hours is the ceiling. Past that, restore a new sandbox from a filesystem snapshot, which brings back files but not processes.
• E2B: Hobby sessions last 1 hour and Pro sessions 24 hours. Pausing resets the clock.
• Vercel Sandbox: the 24-hour limit applies to each session, not the sandbox. A persistent sandbox resumes from its filesystem snapshot, so its total lifetime is open-ended, but processes restart each session.
• Daytona: sandboxes stop after 15 idle minutes unless you turn that off.
• Beam sandboxes: keep_warm_seconds is the sandbox's TTL. Set it to -1 and the sandbox runs until you terminate it, or reset the remaining time with sb.update_ttl().
• Beam VMs: no session cap at all. A VM runs until you stop or pause it, and an idle timeout can pause it and wake it on the next request.

A VM is often the better fit for multi-day agents, because it keeps systemd services, Docker containers and a durable root disk across stops.

The alternatives, one by one

Pick by the job the agent does. Each review opens with the workload it fits.

Beam: GPU sandboxes and persistent VMs

Beam fits teams that want Modal's mix of sandboxes and GPUs without the 24-hour cap, plus a persistent machine for agents that work over days. It offers two products, and it helps to keep them apart.

Beam sandboxes boot in seconds and run as containers, or as microVMs with use_vm=True. They attach a GPU with one argument, such as Sandbox(gpu="RTX4090"), and run Docker with docker_enabled=True. Memory snapshots fork a running sandbox into as many copies as you need, and egress can be blocked or limited to an allow list of up to 64 hosts. Sandboxes bill by the millisecond at $0.0000375 per core-second and $0.0000064 per GiB-second, slightly under Modal's sandbox rate.

Beam virtual machines are persistent CPU microVMs with their own kernel, systemd and a durable root disk. Docker, Compose and Buildx are preinstalled, pause keeps RAM and running containers, and you get SSH through an authenticated tunnel and a browser desktop. They bill per second while running, at $0.0252 per vCPU-hour and $0.0054 per GiB-hour, and have no GPUs. Our Docker sandbox alternatives guide covers running Compose on them.

Where Modal wins: a Go SDK (Beam has Python and TypeScript), a mature Python developer experience, and $30 of monthly credits on a plan with no platform fee. Beam's runtime, beta9, is open source under AGPL-3.0 if you want to self-host, though the self-hosting guides don't cover VMs, and Beam can also run workloads in your own AWS, GCP or Azure account. Rates for every product are on the pricing page.

E2B: Firecracker microVMs with pause and fork

E2B is the pick for CPU agents that need to branch a running session. Every sandbox is a Firecracker microVM, and pause, snapshots and fork all keep memory, which is the area where Modal is weakest.

At $0.000014 per vCPU-second and $0.0000045 per GiB-second, E2B is cheaper per hour than Modal or Beam sandboxes. Hobby accounts get a one-time $100 credit and 1-hour sessions. Pro costs $150 a month and allows 24 hours and 100 concurrent sandboxes. E2B doesn't offer GPU sandboxes, and Docker needs a custom template. Our E2B pricing breakdown covers the plans, and the E2B alternatives guide compares it against a wider field.

Daytona: the widest catalog

Daytona offers container, Linux VM, Windows and GPU sandboxes behind one SDK, with SDKs in Python, TypeScript, Ruby, Go and Java. Pick it when you need GPUs, Docker and Windows from one vendor.

CPU sandboxes bill at $0.0504 per vCPU-hour and $0.0162 per GiB-hour, the same hourly figure as E2B at this size. GPUs are listed as preemptible, starting at $0.57 an hour for an RTX 4090. Sandboxes are containers by default, memory pause and fork need a VM class, and sandboxes stop after 15 idle minutes unless you change that. More detail is in our Daytona alternatives roundup.

Vercel Sandbox: Firecracker for TypeScript and Python apps

Vercel Sandbox suits teams already on Vercel whose agents spend most of their time waiting on a model. Each sandbox is a Firecracker microVM with a dedicated kernel, and it can run Docker with sudo.

Its pricing differs from the rest: Active CPU at $0.128 an hour counts only time the CPU is busy, and memory bills at $0.0212 per GB-hour the whole time the sandbox runs. Sandboxes are persistent by default, saving the filesystem on stop and resuming on the next call. Pro sandboxes top out at 8 vCPUs and 16 GB, Hobby sessions last 45 minutes, and Vercel lists no GPU option.

Self-hosting a sandbox runtime

If the code has to stay on your own servers, you can run the isolation layer yourself with gVisor, Kata Containers or Firecracker, or deploy an open-source platform such as beta9. Expect real operational work: images, networking, scheduling and cleanup are yours to build. Our guide to self-hosting a code sandbox walks through what that takes.

How to choose a Modal Sandboxes alternative

Start from the Modal limit that's blocking you. Most teams end up with one of these:

• Sessions longer than 24 hours: Beam sandboxes with keep_warm_seconds=-1, or a Beam VM for work that spans days.
• GPU sandboxes and Docker from one vendor: Beam sandboxes or Daytona.
• Forking a running CPU sandbox, memory included: E2B, or Beam sandboxes if you also want GPUs on the same platform.
• The lowest per-hour sandbox rate: E2B or Daytona at the list rates in the table.
• Mostly idle agents on Vercel: Vercel Sandbox, since CPU bills only while it's busy.
• Code that never leaves your servers: a self-hosted runtime, or Beam in your own cloud account.

FAQ

What are the best alternatives to Modal Sandboxes?

Beam, E2B, Daytona and Vercel Sandbox are the main managed alternatives. Beam fits GPU sandboxes and long-running agents, E2B fits CPU agents that fork running sessions, Daytona covers GPUs and Windows, and Vercel Sandbox fits mostly idle agents on Vercel. gVisor, Kata Containers and Firecracker are the self-hosted route.

Is there a Modal sandbox alternative with GPUs?

Yes. Beam sandboxes attach a GPU with one argument and also support Docker, and Daytona offers preemptible GPU sandboxes. E2B and Vercel Sandbox don't offer GPUs. On Modal itself, GPU sandboxes run on gVisor only, so they can't use Docker or memory snapshots.

Can a Modal sandbox run longer than 24 hours?

No. The timeout maxes out at 24 hours, and Modal suggests restoring a new sandbox from a filesystem snapshot to continue. Beam sandboxes have no documented maximum when keep_warm_seconds is -1, and Beam VMs run until you stop them.

How much do Modal Sandboxes cost?

Modal bills sandboxes at three times its list rate: $0.00003942 per physical core per second and $0.00000667 per GiB per second, or about $0.19 an hour for one physical core and 2 GiB. The Starter plan has no platform fee and includes $30 of monthly credits; Team costs $250 a month plus usage.

Modal vs E2B: which should I use?

Use Modal if your agents need GPUs or you already run inference on Modal. Use E2B for CPU agents that pause and fork with memory, since every E2B sandbox is a Firecracker microVM and its fork API is mature. E2B is also cheaper per hour at the same size.

Can Modal Sandboxes run Docker?

Yes, on the VM runtime only. Create the sandbox with runtime="vm" to get its own Linux kernel. GPU sandboxes can't use that runtime, so Docker and a GPU can't share a Modal sandbox. Beam sandboxes run Docker with docker_enabled=True and offer GPUs.

Run your agents without a 24-hour cap

Beam sandboxes attach GPUs, fork from memory snapshots and run until you terminate them, and Beam VMs keep a full Linux machine with Docker ready for agents that work over days. Create a Beam account and start a sandbox from the Python or TypeScript SDK.