Render Sandboxes vs Vercel Sandboxes

If you're adding code execution to an AI app builder, you're likely choosing between Vercel Sandbox and Render Sandboxes. Both give you isolated Linux microVMs built for untrusted and agent-generated code. The decision comes down to session length, idle behavior, persistence, and where your backend runs.

The short answer:

• Vercel Sandbox fits teams whose Vercel frontend and functions drive the sandbox, or who need multiple regions, public preview URLs, or GA status today.
• Render Sandboxes fits teams whose backend, database, and workflows already run on Render, and teams running long agent sessions. A Render sandbox can run indefinitely, suspends itself when idle, and can restore running processes from a runtime snapshot.

This comparison covers images and runtimes, session limits, persistence, and where the backend that drives the sandbox runs. For the broader platform view, see Render vs Vercel.

What's the same: isolation and billing

Isolation. Both products run each sandbox in its own Firecracker microVM. Your agents can install packages, write files, and run generated code without touching your infrastructure.

Billing. Both products bill for active CPU, so time spent waiting on a model or a person doesn't count. Both also bill for memory while a sandbox runs.

• Vercel Pro: $0.128 per Active CPU hour and $0.0212 per GB-hour of provisioned memory in the default iad1 region, in 1-minute minimum increments, plus $0.60 per million sandbox creations. The Hobby plan includes 5 hours/month of Sandbox Active CPU.
• Render: $0.12 per active CPU hour, plus memory at $0.038/hour per 2 GB (about $0.019 per GB-hour).

Snapshot storage costs $0.08 per GB-month on both.

Idle time is where the costs diverge most. By default, a Render sandbox suspends after 15 minutes without a command, and Render stops billing CPU and memory while it's suspended. A Vercel sandbox bills provisioned memory until its session timeout ends or you call stop().

Where each product stands today

Render Sandboxes is in public beta. APIs, defaults, and limits might change during the beta. Sandboxes are available on all workspace plans, in Oregon. The beta includes:

• Creating sandboxes, running commands, and transferring files and directories.
• Custom images built from OCI images.
• Runtime snapshots (filesystem, memory, and running processes) and filesystem snapshots.
• Automatic idle suspension, with resume on the next command.
• An outbound network policy on each sandbox: allow all, allow a list of domains, or deny all.
• Up to 10 sandbox groups per workspace, each with its own concurrency limit.

Some features aren't available yet. Sandboxes can't reach your other Render services over the private network, and they have no public URLs or SSH access. Credential brokering and scoped API keys are in early access.

Render's roadmap includes private networking, more regions, SSH and public URLs, and CPU and memory bursting. Two more capabilities are coming soon:

• Shared Filesystems, which give sandboxes and workflow tasks the same persistent files, so parallel agents can read shared inputs and build on each other's work.
• Full computer use for agents inside a sandbox.

Vercel Sandbox is generally available, and so is persistence. Drives for Vercel Sandbox are in public beta.

Images, runtimes, and Docker

Vercel boots a sandbox from a Vercel Managed Image, a shared or public image, your own OCI image stored in Vercel Container Registry, or a saved snapshot. The default vercel/sandbox/universal image includes Node.js LTS, Python 3.14, coding agents, and common utilities. Sandboxes can run Ubuntu, Arch Linux, or another Linux distribution.

Render boots a sandbox from Render's default image or from a custom image built from an OCI image (linux/amd64). You can bake in your agent harness, dependencies, and configuration, so sandboxes start with nothing to install.

Both products run Docker inside the sandbox. Vercel documents container runtimes, VPN clients, and FUSE filesystems running with sudo. Render supports Docker and Docker Compose, so an agent can start a copy of your app and its database side by side and test changes before you deploy.

What this means for an AI app builder

• Prebuilt environments. Both start from an OCI image. Vercel pairs this with its own container registry.
• Container-based testing. Both let an agent start containers inside the sandbox.
• Reusing a prepared state. Both snapshot a configured sandbox. Only Render's runtime snapshots carry running processes and memory into a new sandbox.

Session length, concurrency, and storage

The two products handle session length differently:

• Vercel defaults to a 5-minute timeout, which you can raise at creation or with sandbox.extendTimeout(). A session caps at 24 hours on Pro and 45 minutes on Hobby, and the cap resets each time a persistent sandbox stops and resumes.
• Render has no session cap on paid workspaces. The runtime timeout defaults to 24 hours, accepts any value from 60 seconds to 30 days, or can be disabled. A separate idle timeout suspends the sandbox after 15 minutes without a command. You can set it from 5 minutes to 24 hours, or disable it. Disable both timeouts to run a sandbox indefinitely.

Per-sandbox resources are now close. Vercel Pro allows up to 8 vCPUs, 16 GB of memory, and a 64 GB disk, and Enterprise goes to 32 vCPUs and 64 GB. Render offers four plans up to 8 CPU and 16 GB, with 40 GB of disk.

For concurrency, Vercel Pro allows 10,000 concurrent sandboxes. Render Pro defaults to 1,000 per workspace, with up to 5,000 on request. Suspended sandboxes don't count toward Render's limit.

How the limits map to common workloads

• Short interactive runs. Both fit. Vercel's 5-minute default stops quick runs automatically.
• Multi-day agent sessions. Render fits best. A sandbox can run for days, such as during a codebase migration, while keeping its processes and memory, and it suspends itself between bursts of work.
• Builds and test suites. Both offer 8 CPU and 16 GB. Vercel has the larger disk, at 64 GB vs 40 GB.

Limits at a glance

Persistence and snapshots

Vercel sandboxes are persistent by default. When a session stops, the SDK snapshots the filesystem, and the next SDK call on that sandbox's name resumes it. You can opt out of persistence. Manual snapshots capture the filesystem and installed packages, and they expire 30 days after last use by default. You can change that retention or keep them indefinitely. Automatic snapshots consume billed Snapshot Storage.

Render handles persistence through idle suspension and snapshots. When a sandbox goes idle, Render checkpoints and suspends it, and your next command or file transfer restores it, as long as it was suspended within the last 30 days. For explicit checkpoints, Render offers two snapshot kinds:

• Runtime snapshots, the default, capture the filesystem plus memory and running processes. An agent restored from one picks up mid-task, and Render reports restores 3–10x faster than starting fresh. Restoring requires the same compute plan.
• Filesystem snapshots capture files and installed tools, and you can restore them onto a different plan.

Snapshots expire 30 days after capture by default, and restoring from one doesn't extend that. You can name a snapshot so that new sandboxes always restore from the newest one with that name.

What this means in practice

• Resumable sessions. Both products resume automatically. Vercel resumes by name; Render resumes a suspended sandbox on its next command.
• Resuming mid-task with memory intact. Only Render's runtime snapshots restore running processes.
• Pre-warmed environments. Both work. On Render, rebuild under the same snapshot name before the 30-day expiry.

SDKs and CLI

Vercel offers a JavaScript SDK, a Python SDK, and a Sandbox CLI. The SDK reads credentials after you run vercel link and vercel env pull.

Render offers a TypeScript SDK (@renderinc/sdk 1.5.0+), a Python SDK (render 1.5.0+), and the Render CLI (2.33.0+) with render sandboxes and render sandbox-groups commands. Sandboxes use the same SDK as Render Workflows. Render also publishes setup guides for Claude Managed Agents, Cursor Cloud Agents, and the OpenAI Agents API.

Both products cover Node.js and Python agent stacks. The deciding factor is where that code runs.

Where your backend runs

A service in your stack creates sandboxes, sends commands, and tears them down. When you place the sandbox product next to that service, you keep credentials, deploys, and operations in one place.

If a Next.js app on Vercel drives the sandbox, Vercel Sandbox fits. Run vercel link and vercel env pull so the SDK can read your project's environment. On Pro plans, Vercel charges sandbox usage against your $20/month credit and bills additional usage beyond that.

If your agent backend already runs on Render, Render Sandboxes keeps everything in one workspace. That backend might be a web service, a background worker, or a workflow backed by Render Postgres. Sandboxes use the same API keys as your other Render services, are billed alongside them, and can be placed in a project environment.

Sandboxes also pair with Render Workflows. Workflows handle the steps that should run the same way every time, and sandboxes handle the open-ended agent work. During the beta, sandboxes can't yet reach your Render services over the private network, so traffic between them goes over the public internet.

Verdict

Choose Vercel Sandbox if:

• Your Vercel frontend and functions create and drive the sandbox.
• You need public URLs on exposed ports, multiple regions, static IPs or VPC peering, or GA status today.
• You need credential brokering now.

Choose Render Sandboxes if:

• Your agent backend, database, and workflows already run on Render.
• Your agents run for hours or days and you don't want to manage session caps or timeout extensions.
• Your agent needs to resume mid-task with its processes and memory intact.
• Your sandboxes sit idle between bursts, and you want them to suspend and stop billing on their own.

Decision checklist:

• Where does the code that calls the sandbox SDK run?
• Does a session need to outlast 24 hours, or resume with running processes intact?
• Do you need public URLs, SSH, or private networking today?
• Do you need regions outside Oregon?
• Do you need credential brokering today?

Render Sandboxes is in public beta, and its APIs, defaults, and limits might change before general availability. See the Render Sandboxes docs for the current scope.

Frequently asked questions