Blaxel vs Beam: Sandbox comparison for AI agents

Your coding agent works in production. It writes code, executes it, and shows the user a live preview. Then the user steps away for two hours.

You must either pay for an idle sandbox or destroy it. Destroying it means rebuilding state when the user returns. Keeping it means idle hours dominate the bill. Isolation strength also matters because your agent writes code nobody reviewed.

Blaxel and Beam both offer sandboxes for AI-generated code, but they serve different workloads. Evaluate isolation, lifecycle economics, and deployment flexibility first. Beam focuses on serverless GPU workloads, with sandboxes as a product. Blaxel is the infrastructure foundation for autonomous agents. Its sandboxes preserve session state during standby.

Blaxel fits coding agents, pull request review agents, and data analysis agents executing untrusted code. Beam fits products built around Python ML inference. For a related serverless comparison, see Blaxel vs Modal.

TL;DR:

• Different isolation models: Blaxel runs Firecracker microVMs with per-sandbox kernels. Beam uses gVisor and runc on a shared host kernel.
• Idle cost divergence: Blaxel stops compute charges during unlimited standby. Beam bills the full rate throughout its keep-warm window.
• Blaxel for agent code execution: Coding agents, PR review agents, and data analysis agents running untrusted code fit Blaxel's lifecycle and isolation model.
• Beam for GPU inference: Python ML inference products with GPU endpoints and self-hosting requirements fit Beam's serverless stack.
• Resume vs. restore: Blaxel resumes the same sandbox in place. Beam's snapshot restoration creates a new sandbox with a new identity.

What is Beam?

The Beam platform provides on-demand compute for agents, sandboxes, inference, and GPU workloads. Its company funding history traces Beam to Slai, a Y Combinator W22 company. It raised $7 million from YC, Tiger Global, and several angel investors. Those investors included former GitHub CTO Jason Warner.

Beam V2 documentation covers functions, REST APIs, task queues, and CPU or GPU sandboxes. Beam runs on the beta9 engine. Beta9 uses the GNU Affero General Public License 3.0 (AGPL-3.0). The license supports self-hosting.

What is Blaxel?

Blaxel's products fall into three groups.

• Compute: Sandboxes and Batch Jobs run agent workloads.
• Storage: Agent Drive is a distributed filesystem in private preview, alongside Volumes for durable storage.
• Networking: Blaxel manages custom domains, proxy secrets injection, and dedicated egress gateways in private preview.

Together, these groups connect execution, durable data, and network controls under one account.

Sandboxes retain filesystem and memory state during unlimited standby. Unlimited standby does not guarantee durable long-term persistence. Use Volumes when data must remain available for months or across sandbox replacement. Blaxel is a first-class sandbox provider in the OpenAI Agents SDK.

The SDK builds on OpenAI's Codex harness. Blaxel Sandboxes handle the execution layer.

Blaxel vs Beam: feature comparison

The table compares isolation, lifecycle, state, networking, language support, pricing, and compliance. Each row describes a tradeoff rather than assigning a winner.

CIDR means Classless Inter-Domain Routing. CIDR allowlists restrict traffic to specified network address ranges.

When Blaxel is the better choice

Blaxel fits agent code execution that is sporadic, stateful, and untrusted.

• Coding agents users return to: Live previews often need to survive long gaps between user sessions. Blaxel drops disconnected sandboxes into standby without compute charges. It resumes the same sandbox in under 25ms with files, memory, and processes intact. This is resume latency, not initial creation, while Beam's documented lifecycle ends in termination. Beam sandboxes expire after their keep_warm_seconds window, and snapshot restoration creates a new sandbox.
• PR review agents with bursty load: Pull request reviews arrive sporadically throughout the day. Between reviews, standby avoids paying for continuously active compute. The repository and running tools remain available for the next review.
• Untrusted, multi-tenant code: Use NIST container security guidance when assessing adversarial, multi-tenant execution. Apply the isolation criterion in the comparison table to your threat model.
• A unified stack from one provider: Sandboxes, Agent Drive in private preview, Volumes, and Batch Jobs share one backbone. Blaxel also manages networking around these products. Egress controls and storage therefore sit behind the same account as execution.

Unlimited standby preserves a session without imposing a fixed duration. However, standby snapshots are not guaranteed durable storage. Attach a Volume before relying on files for long-term retention. If agents idle between sessions and run code you didn't write, Blaxel fits that workload.

When Beam may fit better

Beam fits workloads centered on Python ML inference and teams with strict self-hosting requirements.

• Python ML inference products: Beam fits products centered on Python ML inference rather than newly generated agent code. Beam offers RTX 4090, A10G, and H100 endpoints, plus A100 and B200 GPUs on demand. Task queues support fan-out processing. Checkpoint restore snapshots memory after model loading on RTX 4090, H100, and A10G. Beam markets sub-second container starts, but end-to-end GPU cold starts are about 30 seconds because model loading dominates.
• Teams with hard self-hosting requirements: Beta9 supports self-hosting on a Kubernetes cluster. Beam's Bring Your Own Cloud (BYOC) option covers AWS, GCP, Azure, Hetzner, and other clouds. The Beam BYOC option extends that deployment flexibility. Teams must still operate Beta9.
• Known Beta9 tradeoffs to weigh: Reported issues include an external-worker crash during machine registration. Other reports cover deleted Bitnami images in Helm dependencies. Beta9 also lacks ARM64 image support for Apple Silicon. Blaxel offers BYOM and private VPC interconnect, with sandbox runtimes on customer bare metal. Blaxel retains its managed control plane, so teams requiring full self-hosting should choose Beta9.

Pricing comparison

Figures below assume a 1-core, 8 GB sandbox running for one hour. Prices are stated as of May 2026. Beam bills compute by the second according to its pricing page. CPU costs $0.0000528 per second per core, and Beam doesn't define one core as two vCPUs. RAM adds $0.0000056 per second per GB.

Use Blaxel pricing details for current pre-configured tiers, usage rates, and free credits.

Blaxel's pricing follows three published categories:

• Free: Up to $200 in free credits plus usage costs.
• Usage-based pricing: Current pre-configured tiers and usage rates appear in Blaxel's pricing details.
• Add-ons: Email support, live Slack support, and HIPAA compliance are available.

Active runtime lands in a similar range on both platforms. Beam bills keep-warm time, while Blaxel stops compute charges during standby but may charge for snapshot and volume storage.

The Build0 case study documents the effect on a production workload. Build0 CTO Phil Dang said, "Blaxel allows us to save 70% to 80% of the cost compared to previous solutions." The savings came from reducing paid idle compute rather than lowering active runtime rates.

Objections engineers raise when choosing Blaxel over Beam

The common objections concern state restoration and isolation boundaries. Both affect whether a sandbox can safely continue an interrupted production task.

"Beam has memory snapshots. Isn't that the same as standby?"

No. Beam's snapshot_memory() captures memory state, running processes, and exposed ports. Restoring it calls create_from_memory_snapshot and initializes another sandbox. Beam also documents snapshot restoration and mentions pause-and-resume capabilities. However, its configuration page lacks a dedicated pause API or explicit in-place resume operation. A restored sandbox therefore has a new identity.

Applications must re-establish preview URLs, open connections, and held handles. This behavior works well when forking a prepared environment. It also supports seeding multiple sandboxes from the same state. Blaxel instead resumes the same session with its memory, processes, and filesystem state. Use a Volume when files also require guaranteed long-term retention.

"Is gVisor isolation enough for our code?"

Containers are standard for running software your team wrote and reviewed. gVisor strengthens that model by intercepting system calls in a user-space kernel. For trusted code, that boundary can be appropriate. AI-generated and adversarial code creates a different threat model. Apply the table's isolation criterion before running unreviewed code across multiple tenants.

Beam's network controls operate alongside its isolation boundary. block_network disables outbound traffic. CIDR allowlists restrict reachable addresses. These controls reduce what compromised code can access. They complement, rather than replace, the selected workload isolation boundary.

Run the Blaxel vs Beam comparison on your own workload

Start from what your sandboxes actually do. Beam's endpoints and task queues fit Python ML inference services. Agent code execution creates different requirements. Untrusted code must not reach the host or a neighboring sandbox. Sessions may need to survive multi-hour gaps with running processes intact.

Idle hours should not produce active compute charges. Blaxel preserves complete filesystem and memory state through unlimited standby. Network inactivity automatically returns disconnected sandboxes to standby. Use Volumes when data requires guaranteed long-term retention.

The same product stack covers Agent Drive in private preview, Volumes, Batch Jobs, and managed networking. Agent Drive shares context and artifacts across sessions. Volumes provide durable storage, while Batch Jobs handle parallel asynchronous work. Run your agent on both platforms for a week, comparing latency, restoration, isolation requirements, and the final bill. You can sign up free to deploy a Blaxel sandbox for that test.

FAQs about Blaxel vs Beam

These questions summarize the lifecycle, pricing, and networking differences. Use them to translate platform features into deployment requirements.

Does Beam support pausing and resuming sandboxes?

No pause or standby API appears in Beam's V2 documentation. The documented lifecycle moves through create, launch, use, and terminate. keep_warm_seconds keeps a sandbox alive, and -1 keeps it running until termination. That active period counts as billable usage.

Snapshots offer another path, but restoration creates a new identity. Applications must reconnect preview URLs, handles, and network sessions. Blaxel follows an in-place standby model that resumes with session state after connections close. Unlimited standby isn't durable retention, so use Volumes for independently persistent files. Choose snapshots for new identities, or standby when identity must persist, then test active previews before production.

How much does an idle agent sandbox cost on each platform?

On Blaxel, standby removes the compute charge. Snapshot storage and attached Volume storage can still accrue charges. This model suits workloads with short bursts separated by long user pauses. On Beam, the configured compute meter runs throughout the keep-warm window, even without code execution. A coding agent workload with ten minutes of work during an hour spends most of that session idle.

Compare active and idle time because a slightly lower active rate can still cost more overall. Results depend on how long sessions remain open between useful operations. Multiply Beam's configured CPU and RAM rate by the full keep-warm duration. For Blaxel, separate active GB-seconds from standby snapshot and Volume storage. Model production pause distributions to reveal whether idle time dominates the bill.

Which platform gives me control over sandbox networking?

Blaxel manages networking around its sandboxes. Custom domains expose sandbox previews through a product's own hostname. Dedicated egress gateways provide predictable outbound IPs for allowlists and remain in private preview. Proxy secrets injection keeps raw API keys outside sandbox code.

Beam provides block_network for disabling outbound traffic and CIDR allowlists for restricting destinations. CIDR allowlists support up to ten entries per sandbox. Custom domains and per-customer egress IPs remain undocumented in Beam V2. If you require both, note that Blaxel's gateways remain in private preview and custom domains apply to sandbox previews. Before choosing, test hostnames, allowlists, and secrets, then confirm the private-preview timeline.