Free sandbox APIs for AI agents (2026)

Hosted sandbox APIs give free use in three forms: credit (Prized, E2B, Daytona, Sprites, Blaxel), an allowance that comes back every month (Modal, Vercel Sandbox, Freestyle, CodeSandbox), or a free plan with fixed limits (Tensorlake). What it buys differs more than the dollar figure: how long a sandbox may run, how many run at once, how big each is, and whether you need a card.

Free use at a glance

"Not stated" means the vendor's pages don't say. Past a monthly allowance, Vercel pauses sandbox creation and Freestyle pauses VMs until it resets; past a one-time credit, you top up or start a plan. Cloudflare Sandboxes have no free use: they need the Workers Paid plan, $5 a month. Together Code Sandbox is turned on through its sales team.

Prized's free tier, exactly

• $30 of credit, once per person, no card. It does not refill, and sandboxes draw on it at $0.04 per vCPU-hour, $0.0125 per GB-hour of memory and $0.0001 per GB-hour of disk: a 2 vCPU, 4 GB sandbox is $0.131 an hour. The $30 of free credit covers about 2,700 five minute sandboxes of 2 vCPU and 4 GB.
• Limits while the balance is free credit alone: 10 sandboxes at once, 20 vCPU and 40 GB running across the workspace, each up to 2 vCPU and 4 GB, 60 minutes of running in all per sandbox, and 100 GB of disk across the workspace's sandboxes (Free tier).
• Paused sandboxes keep their memory and disk, on the machine they ran on, until 30 days after their last use, then are deleted (Paused retention).
• Included: pause with memory, fork into live copies (the copies keep the parent's deletion time), outbound internet, and both templates: prized-base-v1 (Ubuntu with Python 3, Node.js 22 and git) and prized-agent-v1, which adds Claude Code and Codex.
• The free credit's rules hold: one process at full CPU for 30 minutes can pause the workspace's sandboxes (Free credit).
• To lift it: a top-up from $10 or a plan lifts a workspace to the full quotas: 24 hours of running by default, up to 7 days, and up to 32 vCPU and 128 GB a sandbox.
• An account a coding agent makes with your email through agent sign-in can get the credit, once per inbox, if the sign-up passes Prized's checks (Boxes and billing).

Sandboxes have no GPUs. Not yet: your own image, Docker, root, and regions other than Oregon (Not yet).

Start a sandbox in one call

1. Get a key: Open Sandboxes signs you up with the $30 of free credit and no card; click Create API key and export it as PRIZED_API_KEY. A coding agent can make the account and its key with your email address instead (Agent quickstart).
2. Create a 2 vCPU, 4 GB sandbox with curl and jq. The call holds its answer up to 8 seconds while the sandbox starts and keeps its address in TOOLBOX; a command sent while it is still starting waits up to 10 seconds for it. It deletes itself after 60 minutes of running:

TOOLBOX=$(curl -s -X POST "https://api.prized.dev/api/v1/sandboxes?wait=running" -H @<(echo "Authorization: Bearer $PRIZED_API_KEY") -H "Content-Type: application/json" -d '{"template":"prized-base-v1","resources":{"vcpu":2,"memoryMb":4096},"maxRuntimeMin":60}' | jq -er '.sandbox.toolboxBase // error(tojson)')

3. Run a command in it:

curl -s -X POST "$TOOLBOX/process/execute" -H @<(echo "Authorization: Bearer $PRIZED_API_KEY") -H "Content-Type: application/json" -d '{"command":"python3 --version"}'
# {"stdout":"Python 3.12.3\n","stderr":"","exitCode":0,"durationMs":41}

A refused create prints its error instead, with the free-tier limit it hit (Free tier). Files, background processes, pause, fork and delete are one call each (Sandbox API).

Host one yourself

Open-source sandboxes cost what the machines under them cost, and you run them yourself:

• E2B's runtime (Apache-2.0): the stack behind E2B's cloud, for your own machines.
• OpenSandbox (Apache-2.0), formerly at alibaba/OpenSandbox.
• microsandbox (Apache-2.0): a microVM runtime and library that runs locally.
• Agent Sandbox (Apache-2.0): isolated, stateful workloads on your Kubernetes cluster.
• Daytona (AGPL-3.0): free to use and fork, but no longer maintained; Daytona moved its core development to a private codebase in June 2026.

Common questions

Which sandbox API is free without a credit card?

Prized, E2B and Daytona say so on their own pages: $30, $100 and $200 of credit. Modal asks for a payment method on file before its $30 a month applies.

Which free tier runs a sandbox longest?

Daytona and CodeSandbox set no run time limit, and Freestyle and Sprites list none, though Daytona stops a sandbox after 15 minutes with no toolbox calls, SSH or preview traffic unless you turn auto-stop off, and CodeSandbox hibernates one after the idle timeout you set, up to 24 hours. Modal allows 24 hours, Tensorlake 2 hours, E2B 1 hour at a time and Vercel 45 minutes a session. Prized's free tier gives each sandbox 60 minutes of running in all, and a top-up from $10 lifts it to 24 hours by default and up to 7 days.

Is there a free sandbox API that keeps memory through a pause?

Prized and E2B keep a paused sandbox's memory on their free use, Blaxel's standby and CodeSandbox's hibernation save it too, and a Sprite keeps it while it sleeps warm. Daytona does it on its Linux VM and Windows sandboxes, not its default containers. On the free tier a paused Prized sandbox is kept, on the machine it ran on, until 30 days after its last use; E2B keeps paused sandboxes with no time limit.

Which free sandbox API fits a coding agent?

One with outbound internet, a run long enough for its task, and a way to keep its state between turns. On Prized, the prized-agent-v1 template has Claude Code and Codex installed, and the Prized skill teaches your coding agent the calls.

Sources

Checked October 31, 2026:

• E2B: pricing (Hobby credit, card, sessions, concurrency), billing (sizes, paused retention).
• Daytona: pricing (free compute, card), limits (tiers), sandboxes (sizes, auto-stop, pause), repository (no longer maintained).
• Modal: pricing (Starter credit), billing (payment method), sandboxes (timeouts).
• Vercel Sandbox: pricing and limits (Hobby allowance, sessions, concurrency, sizes).
• Freestyle: pricing and limits (free allowance, concurrency, sizes), VM lifecycle (pause keeps memory).
• CodeSandbox SDK: pricing, credits (400 a month on the free plan), SDK pricing (concurrency, VM sizes), hibernation (memory and disk), create (hibernation timeout).
• Sprites: Sprites (trial credit), lifecycle (size, warm and cold sleep).
• Blaxel: pricing (free credit, Tier 0 sandboxes, standby keeps memory), expiration (Tier 0 expiry).
• Tensorlake: pricing (free plan), billing (limits).
• Cloudflare Sandboxes: Containers pricing (Workers Paid).
• Together Code Sandbox: docs (access through sales).
• Open source: each project's GitHub repository (license, latest release).

Something here out of date? Write to team@prized.dev.