The best AI agent sandboxes.

An agent sandbox runs untrusted code separately. It usually exposes commands and files. Many products also expose network controls. Some preserve state across sessions.

A development sandbox behaves like a computer. A function sandbox behaves like isolated execution. A browser session isolates web interaction. These categories overlap only partly.

Your model remains outside some sandboxes. The agent loop may run elsewhere. That split affects secrets and networking. It also affects observability.

Start with the dangerous capability. Code execution needs process containment. Browser interaction needs browser isolation. Desktop control needs another boundary. Do not merge these silently.

General agent execution established eligibility. Each vendor needed command and file controls. Clear isolation documentation supported buyer confidence. Lifecycle controls shaped production usefulness.

Persistence received separate review. Resource configuration mattered for expensive workloads. Deployment fit mattered for existing cloud stacks. Pricing clarity completed the ranking.

Published speed claims received no ranking credit. Published scale claims established available product paths only. We did not infer security from marketing. Independent testing remains necessary.

The ranking favors broad agent execution. Specialist workloads may change the order. Each entry includes one honest limitation. Read it before evaluating price.

Vendor documentation establishes product shape. It does not prove containment strength. Security review must follow architecture review.

E2B offers a compact developer entry point. Its SDK creates an isolated cloud environment. Agents can run commands and manage files. Internet access is also documented.

E2B templates customize the starting environment. Paid plans extend session duration. They also raise standard concurrency. Usage billing runs by sandbox seconds.

Daytona presents a broader computer model. Containers cover normal code execution. VM classes add dedicated operating systems. GPU sandboxes cover accelerated workloads.

Daytona also emphasizes persistent state. Stopped sandboxes retain files by default. VM pause and resume preserve memory. Snapshots create reusable starting points.

Choose E2B for a simple general baseline. Choose Daytona for deeper workspace lifecycle. Verify resource class differences before committing.

Modal places sandboxes inside broader compute infrastructure. Builders configure CPU and memory. GPU-backed sandboxes support accelerated tasks. Billing follows requested or actual resources.

This fit suits variable compute workloads. It also suits large parallel execution. Modal offers several client languages. Python remains its primary application language.

Runloop focuses on software-engineering agents. Devboxes act like virtual developer workstations. Blueprints define reusable environments. Snapshots and resume support longer workflows.

Cloudflare Sandbox SDK fits Workers applications. Durable Objects identify sandbox instances. Containers run commands and manage files. Services can be exposed through controlled URLs.

Cloudflare currently has two API tracks. Stable supports existing deployments. The preview targets the upcoming major release. New projects need deliberate version selection.

The broadest sandbox is rarely automatically best. Extra capabilities create extra review work. Persistent state also creates retention duties. Network access changes the threat model.

Use the matrix before vendor trials. Choose one primary workload. Add secondary capabilities only when required. Keep the final boundary explainable.

E2B charges each running sandbox by second. CPU, memory, and storage have separate rates. Paid subscriptions change standard session and concurrency limits.

Daytona charges reserved sandbox resources. Billing tracks CPU, memory, and disk usage. Lifecycle state affects which resources remain charged. The dashboard exposes per-sandbox usage.

Modal bills by second. Charges use requested or actual resource usage. The higher value wins. GPU pricing follows selected hardware.

Runloop charges subscription and usage separately. CPU, memory, builds, and storage use distinct meters. Suspended devboxes stop compute charges. Storage charges continue.

Cloudflare Sandbox SDK inherits container pricing. Workers and Durable Objects add related charges. Optional logs add another meter. Model one complete application stack.

Legba publishes a ready agent skill. It provides routing and isolated browser sessions. Sessions stay scoped per task. They run on Legba infrastructure.

Legba does not publish general code execution. It also publishes no shell environment. File-system controls remain undocumented. Therefore, Legba cannot rank here.

Some architectures still need both boundaries. A code sandbox runs agent tools. A browser service handles web interaction. Legba may serve the browser boundary.

E2B ranks first for balanced general use. Daytona follows for persistent workspace depth. Modal wins flexible compute. Your risk model decides the final choice.