Vercel Sandbox vs E2B

Code that an AI agent produces is shaped by its inputs, and prompt injection means those inputs can be manipulated by an attacker. If that code shares an execution environment with your application, it inherits your credentials, network access, and filesystem. Sandboxes prevent this by running generated code in an isolated VM where it cannot reach the agent's secrets or your infrastructure.

Vercel Sandbox and E2B both provide this isolation. The differences are in what each product builds on top of it. This guide compares both across compute, security, and pricing so you can choose which one fits what you're building.

• How Vercel Sandbox and E2B compare
• Where Vercel Sandbox goes deeper
• Where E2B goes deeper
• What they cost
• When to choose Vercel Sandbox or E2B
• Get started with Vercel Sandbox

Vercel Sandbox is a compute primitive within the Vercel platform, focused on disposable code execution with security controls for untrusted code. E2B is a standalone sandbox platform focused on persistent agent environments with built-in execution tools. Both use Firecracker microVMs for isolation, but they optimize for different workload patterns.

Both products give each sandbox its own Linux kernel, preventing the cross-sandbox escapes that container-based isolation leaves open.

The concurrency and runtime limits reflect each product's lifecycle model. Vercel Sandbox supports more concurrent sandboxes with shorter max runtimes because sandboxes are disposable, so a platform serving many users creates and destroys them continuously. E2B supports fewer concurrent sandboxes with longer sessions because sandboxes persist and resume on demand rather than being replaced.

E2B decouples RAM from CPU count, allowing configurations like 2 vCPUs with 8 GB for memory-heavy workloads that don't need proportional compute. Vercel Sandbox ties RAM to CPU at 2 GB per vCPU, which simplifies configuration and reaches a higher ceiling (16 GB at 8 vCPUs) for workloads that need both. Vercel Sandbox currently operates in one region (iad1, US East) while E2B offers US and EU regions.

Both products provide VM-level isolation. The key difference is what controls exist at the network boundary and how secrets are handled.

Vercel Sandbox adds application-layer controls on top of VM isolation. Credential brokering keeps secrets outside the sandbox entirely, and a runtime network firewall controls what outbound connections the sandbox can make. In Vercel Sandbox, denied ranges always override allowed ranges, so a deny rule cannot be accidentally bypassed. E2B inverts this: allow rules take precedence, which means explicitly allowed traffic passes even if a broader deny rule would otherwise block it. E2B relies on VM-level isolation as its primary boundary, with environment variables for secret storage. See the credential brokering and network firewall deep dives below.

E2B provides infrastructure flexibility that Vercel Sandbox does not currently offer. Bring Your Own Cloud (BYOC) deploys sandboxes into a customer's own AWS VPC on Enterprise plans (GCP and Azure planned), and self-hosting is also available. For teams with data residency or compliance requirements that mandate infrastructure control, these options remove the managed-cloud dependency.

The comparison tables above show where the two products overlap. The sections below go deeper into the capabilities that are specific to Vercel Sandbox.

AI-generated code that needs to call authenticated APIs creates a specific security problem. If you pass API keys into the sandbox as environment variables, the generated code can read them and send them anywhere. Credential brokering solves this by keeping secrets outside the sandbox entirely.

A proxy sits outside the sandbox security boundary and intercepts outbound requests. When the sandbox code calls an API endpoint without authentication headers, the proxy injects credentials into the HTTP headers in transit. If the sandbox code tries to set the same headers (to redirect authenticated requests to an attacker-controlled endpoint), the proxy overwrites them. When no transformation rules are configured, TLS passes through end-to-end without interception. Credential brokering transformation rules require Pro or Enterprise plans.

We recommend an architecture where the agent harness and its secrets live in one security context (such as a Vercel Function) while generated code executes in a separate sandbox with no access to agent secrets. This separation ensures that even if generated code is malicious, it cannot reach the credentials that drive the agent workflow.

E2B passes secrets as environment variables that are visible inside the sandbox.

The sandbox network firewall controls what external services a sandbox can reach. The three available modes are allow-all (the default), deny-all (blocks everything including DNS resolution), and user-defined rules combining domain and IP range matching.

Domain matching works through SNI (the TLS handshake field that identifies the target hostname), and CIDR rules handle IP-range and non-TLS traffic. Denied ranges always take precedence over allowed ranges and domain-based rules. Policies update at runtime through updateNetworkPolicy() without restarting running processes, so you can start with deny-all and selectively open access to specific APIs as an agent's execution progresses.

E2B also provides network controls through domain allow lists and IP/CIDR allow/deny lists, with the opposite precedence model: allow rules take precedence over deny rules. E2B supports domain matching in allow lists only (not deny lists), using Host header inspection on HTTP/80 and SNI on TLS/443. Both products use CIDR-based rules for non-TLS traffic.

Active CPU pricing charges only for time the CPU is executing code. Time spent waiting on AI model inference, database queries, API responses, or any other I/O does not count. Active CPU pricing can reduce costs by up to 95% for workloads with bursty or I/O-bound patterns.

On Pro, Active CPU costs $0.128 per vCPU-hour. E2B charges per-second for the full wall-clock time a sandbox is running at $0.0504 per vCPU-hour, regardless of CPU activity. Both products bill memory on wall-clock time (Vercel Sandbox at $0.0212/GB-hr, E2B at $0.0162/GiB-hr). The pricing section includes worked examples.

The SDK and CLI are open-source on GitHub.

E2B offers capabilities that fall outside Vercel Sandbox's focus areas. If your project relies on any of these, E2B may be worth evaluating alongside Vercel Sandbox.

E2B includes a built-in Code Interpreter that runs a headless Jupyter server inside each sandbox. Code executed through runCode() maintains state across calls, so variables, imports, and data loaded in one execution are available in the next. The Code Interpreter supports Python (default), JavaScript/TypeScript, R, Java, and Bash out of the box.

Results come back as structured objects. Matplotlib charts are returned as base64-encoded PNG images, and E2B can extract chart data (type, title, axis labels, data points) for client-side re-rendering. Multiple parallel execution contexts per sandbox allow independent stateful sessions.

Vercel Sandbox executes code through runCommand(), which provides direct shell access. This works well for agent workflows that generate and run complete scripts but does not provide stateful notebook-style execution.

Both products can save sandbox state, but what gets saved is different. Vercel Sandbox snapshots capture the filesystem and installed packages. E2B pause/resume captures the filesystem and complete memory state, including running processes and loaded variables. Resuming takes approximately 1 second.

That distinction matters for workloads that accumulate expensive in-memory state, such as loaded ML models or parsed datasets. Reconstructing that state from a filesystem-only snapshot means re-running setup code, which can take minutes. E2B's memory-state preservation skips that entirely. Auto-resume allows paused sandboxes to wake on inbound traffic or SDK calls, so per-user sandboxes stay available without running continuously.

Vercel Sandbox snapshots default to 30-day expiration, configurable up to never-expires. The filesystem-only approach matches the ephemeral model where each execution starts from a known, deterministic state.

E2B offers a Desktop Sandbox with a full Ubuntu Desktop accessible via VNC for computer use agents that interact with graphical interfaces. Templates support any Docker image as a base (including private registries), and Docker-in-Sandbox enables nested containerization within microVMs. E2B also supports tools from the Docker MCP catalog. MCP (Model Context Protocol) is a standard for connecting AI agents to external services, and these tools run as Docker containers inside sandboxes.

Vercel Sandbox uses Amazon Linux 2023 with dnf package installation and snapshots for environment setup, keeping the microVM boundary clean without nested container runtimes. Agent orchestration and tool calling happen at the application layer through the AI SDK.

The table below compares the paid tiers where each product first supports production-level SDK concurrency.

Vercel's free 5 hours are Active CPU time (recurring monthly), so actual wall-clock time depends on CPU utilization. E2B's $100 one-time credits cover approximately 855 hours of wall-clock compute at the default 2 vCPU / 1 GiB configuration.

The examples below compare equivalent sandbox configurations on each product. Vercel Sandbox bills CPU at $0.128/vCPU-hr only during execution, and memory at $0.0212/GB-hr for the full wall-clock duration. E2B bills CPU at $0.0504/vCPU-hr and memory at $0.0162/GiB-hr, both for the full duration.

2 vCPU, 4 GB RAM (Vercel default config; E2B with matched memory)

At scale (2 vCPU, 4 GB, 1,000 sandboxes/day for 30 days)

The monthly total includes both usage charges and the base plan cost.

The right product depends on what you're building and how long the sandbox needs to live.

The choice comes down to the lifecycle pattern. Ephemeral workloads that create, execute, and destroy sandboxes in minutes benefit from Vercel Sandbox's billing model and security controls. Stateful workloads that maintain execution context across calls, pause and resume between sessions, or need computer use capabilities benefit from E2B's execution primitives.

Try it now with npx sandbox create --connect or sign up for a free account. Pro plans start at $20/month with 2,000 concurrent sandboxes.