Blaxel vs Vercel Sandbox: Agent Infrastructure Compared

Your agent finishes a two-hour coding session. Then the filesystem snapshot enters a fresh virtual machine (VM) on the next request. The dev server is dead. In-memory state is gone.

Blaxel, the infrastructure foundation for autonomous agents, keeps filesystem and memory state in standby. It resumes with memory intact. Vercel Sandbox is an AI Cloud primitive that persists filesystem state only. Its plan limits cap individual sessions.

Blaxel fits production coding agents, pull request (PR) review agents, and tool-calling agents. Vercel Sandbox fits teams already building on Vercel. This comparison covers architecture, state handling, shared-spec pricing, and each platform's strongest use cases.

TL;DR:

• State is the split: Blaxel preserves filesystem, memory, and running processes in standby. Vercel restores a filesystem snapshot into a fresh VM, so dev servers and in-memory state are gone.
• Resume speed and session limits: Blaxel resumes in under 25ms with no session ceiling. Vercel caps at 24 hours on Pro and measured 1.8-3.3s resume in sequential tests.
• Idle billing difference: Vercel bills provisioned memory on wall-clock time even during I/O wait. Blaxel stops compute charges at standby after network inactivity.
• Isolation is parity: Both run Firecracker microVMs with dedicated guest kernels. The evaluation belongs on state behavior, not the isolation boundary.
• Vercel for ecosystem fit: Teams already on Vercel get one vendor, OIDC auth, AI SDK integration, and up to 10,000 concurrent sandboxes on Enterprise.

What is Vercel Sandbox?

Vercel Sandbox is a compute primitive for safely running untrusted or user-generated code. Vercel built Sandbox for AI agents, code generation, and developer experimentation. General availability came on January 30, 2026. Sandbox reached four regions in August 2026.

Each sandbox runs in an isolated microVM. Persistence defaults to an automatic filesystem snapshot when a session stops. The next resume restores that snapshot into a new session.

Sandbox runs on Fluid Compute, Vercel's system for sharing compute across workloads. It also integrates with Vercel's AI SDK and AI Gateway. Authentication uses Vercel OpenID Connect (OIDC) tokens or access tokens.

What is Blaxel?

Blaxel supports agent execution through compute, storage, and networking primitives. These components provide the execution layer where AI agents run production code.

• Compute: Sandboxes provide isolated execution. Batch Jobs support parallel workloads.
• Storage: Agent Drive is a distributed filesystem in private preview. It shares data across agents and sessions. Volumes provide persistent storage for data that must survive runtime loss.
• Networking: Managed custom domains and proxy secrets injection support production traffic. Dedicated egress gateways are in private preview.

Running as isolated Firecracker microVMs, sandboxes preserve filesystem, memory, and process state in standby. After approximately 15 seconds of network inactivity, network auto-shutdown moves them into standby. The Blaxel products page documents indefinite standby without compute charges. Standby doesn't guarantee durable long-term retention, so use Volumes for data that must persist for months.

Blaxel is a first-class sandbox provider in the OpenAI Agents SDK, which builds on OpenAI's Codex harness. Blaxel Sandboxes handle the execution layer beneath that harness. Each agent can receive an isolated sandbox for its task. Delty runs production agent workloads on the platform.

Head-to-head feature comparison

Here's how the two platforms compare across important agent infrastructure dimensions:

When Blaxel is the better choice

Blaxel wins when an agent's session outlives one execution and idle time dominates the bill. Four buyer scenarios come up repeatedly:

• Coding agents with long sessions: Delty's review agent exceeded two-minute latency budgets while cloning 50,000-file repositories. On Blaxel, a new PR wakes a standby sandbox. The repository and processes remain in place. Delty closed over four major enterprise contracts and now analyzes approximately 5,000 PRs monthly. Preserved repository state removed the clone step that broke the latency budget.
• Resume latency in user-facing flows: An August 2026 LogRocket benchmark measured Vercel creation at 1,852ms and resume at 3,333ms. That test ran sequentially. A concurrent-burst measurement put Vercel's median initialization time at 0.67 seconds. Test both patterns against your traffic. Blaxel documents standby resume in under 25ms with full memory state. The shorter delay lets an agent continue processing sooner after waking.
• I/O-heavy workloads: An agent awaiting a large language model response holds memory but performs no work. Vercel stops Active CPU billing during that wait, but provisioned memory continues billing on wall-clock time. Blaxel's network-based shutdown moves the sandbox into standby after network inactivity. Compute charges then stop, although snapshot and volume storage charges remain. An open WebSocket or TCP connection can keep a sandbox active until the idle connection closes.
• Production agent networking: White-labeled previews need managed custom domains. Downstream APIs that whitelist addresses need dedicated egress gateways. Blaxel provides those gateways in private preview. Vercel's Secure Compute IPs apply to Functions and build containers, not Sandbox microVMs. Vercel's Sandbox SDK reference doesn't document custom sandbox domains.

Each scenario traces to one design decision. Blaxel treats the durable runtime as stateful between executions. Volumes provide guaranteed long-term retention when runtime snapshots aren't sufficient.

When Vercel Sandbox may fit better

Vercel Sandbox is the stronger fit in specific situations. Each reflects the platform's ecosystem and network controls. The clearest case is a product already built on Vercel. Sandbox authenticates with Vercel OIDC tokens. It sits beside the AI SDK, AI Gateway, and Fluid Compute. Teams get one vendor, one bill, and one dashboard.

Deep egress control is another strength. The host-level firewall runs outside the microVM. Sandboxed code can't modify or disable it. The firewall supports Server Name Indication (SNI). It also supports SNI and CIDR filtering with live policy updates. CIDR means Classless Inter-Domain Routing. Credential brokering keeps credentials outside the microVM.

Burst scale and large machines favor Vercel too. Pro and Enterprise plans publish concurrency limits of 10,000 sandboxes. They also support 5,000 vCPUs per minute of allocation. Hobby allows 10 concurrent sandboxes. Enterprise large machine limits reach 32 vCPUs and 64 GB of memory.

Compute inside your own AWS account is the final case. Vercel's Enterprise Bring Your Own Cloud option runs compute inside the customer's AWS account. This model addresses data-residency mandates. Blaxel offers Bring Your Own Metal and VPC interconnect through private endpoints. Its control plane always stays on Blaxel. Blaxel doesn't offer a fully air-gapped, run-it-yourself installation.

Check plan gating early if you choose Vercel. Vercel's documentation lists port limits of 15 across Hobby, Pro, and Enterprise.

Pricing comparison

Both platforms meter usage, but they meter different resources. Consider one sandbox with 1 vCPU and 2 GB of RAM. This example uses Vercel's iad1 region in Northern Virginia and August 2026 prices. The shared configuration produces these active, idle, storage, and transfer charges:

• Vercel active usage: Vercel pricing lists Active CPU at $0.128 per hour. Provisioned memory costs $0.0212 per gigabyte-hour. One fully active hour costs $0.128 for CPU and about $0.042 for memory. The combined total is roughly $0.17.
• Blaxel active usage: Blaxel pricing bills $0.0000115 per gigabyte-second of allocated RAM while active. The shared configuration uses 7,200 gigabyte-seconds during one active hour. That produces roughly $0.08 in active memory charges.
• Idle usage: Leave the sandbox idle for the other 23 hours. Vercel excludes I/O wait from Active CPU billing. Provisioned memory continues billing in one-minute minimum increments. That idle memory adds about $0.98. Blaxel moves the sandbox to standby, leaving only storage charges.
• Storage and transfer: Snapshot storage costs $0.20 per gigabyte-month on Blaxel. Vercel snapshot storage costs $0.08 per gigabyte-month. Vercel also charges $0.15 per gigabyte for outbound data transfer.
• Creation charges: The comparison excludes Vercel creation charges because the scenario doesn't define a creation count. Creations depend on whether teams restore, reuse, or replace sandboxes. Add that line item using your measured lifecycle before making a final estimate.

For I/O-heavy agents, the memory-billing difference compounds across idle hours. Base subscription and support choices also affect the final evaluation. The following tiers provide starting points, but active time and stored state determine the resulting bill. Blaxel pricing:

• Free: The plan includes up to $200 in free credits plus usage costs.
• Pre-configured sandbox tiers and usage-based pricing: See Blaxel's pricing page for the most up-to-date pricing information.
• Available add-ons: Teams can purchase email support, live Slack support, and HIPAA compliance.

This structure favors workloads with long idle periods. Compare storage retention, support, and creation patterns alongside active compute costs.

Objections buyers raise, answered

Engineering leaders comparing these platforms tend to raise the same objections.

• "Vercel Sandbox also runs Firecracker microVMs, so isolation is a wash." Correct, and worth saying plainly. Both platforms give each sandbox a dedicated guest kernel. Vercel backs its boundary with a $1 million HackerOne bounty. Isolation is parity. The evaluation belongs on behavior between executions. Blaxel preserves memory and processes across standby. Vercel restores a filesystem snapshot into a fresh VM. For agents, state handling drives user experience and cost.
• "Vercel's persistent sandboxes are GA, so isn't that perpetual standby?" No. Vercel's snapshot documentation says snapshots capture the filesystem and installed packages. Creating a manual snapshot shuts down the sandbox. Running processes and in-memory state don't survive. Blaxel's standby snapshot preserves both, with one documented caveat. External network connections time out and require reconnection after resume. Vercel snapshots expire after 30 unused days by default, though teams can configure that period. Blaxel imposes no standby limit for higher-tier paying users. Standby still isn't guaranteed durable storage, so long-term data belongs on Volumes.
• "We already pay Vercel, so why add a vendor?" Vercel pricing separates Sandbox CPU, memory, and creation charges from Functions and Queues. Blaxel's platform focuses on the agent execution layer. It covers Sandboxes, Batch Jobs, Agent Drive in private preview, Volumes, and managed networking. The SDKs work regardless of where your application runs, including Vercel. Purpose-built infrastructure earns consideration when agents are core to your product.

These objections narrow the decision to state behavior, lifecycle costs, and platform scope. Test those dimensions against your production workload before choosing either provider.

Run your own Blaxel vs Vercel Sandbox evaluation

This decision sets the production ceiling for your agents. Vercel Sandbox fits short, mostly stateless sessions inside the Vercel ecosystem. Other agents accumulate context across hours or days and resume mid-task before users. Blaxel's architecture matches those workloads when I/O wait dominates runtime.

Blaxel sandboxes run in Firecracker microVMs with hardware-enforced isolation. Network-based auto-shutdown moves them to standby after connections close. Standby retains filesystem, memory, and process state without compute charges.

Volumes handle data requiring guaranteed long-term retention. Agent Drive, currently in private preview, shares context and artifacts across sessions. Managed custom domains support white-labeled previews. Dedicated egress gateways are also in private preview.

The fastest evaluation uses your actual agent. Deploy a sandbox, let it idle, and resume it mid-session. Record which state survives. Then compare compute, storage, creation, and transfer charges. Run the same test on both platforms. If Blaxel matches your measured workload, sign up free and run that test today.

FAQs

Can a Vercel Sandbox resume with running processes intact?

No. Vercel snapshots capture the filesystem and installed packages, so a stopped sandbox starts a new VM session from that snapshot. Dev servers, shells, and memory-resident state must be rebuilt. Blaxel standby preserves memory and running processes, so the agent continues from its previous runtime state. External network connections don't survive on either platform. Applications must reconnect databases, APIs, and other remote services after resuming, then verify readiness before serving users.

Can you use Blaxel with Vercel?

Yes. Blaxel provides SDKs for Python, TypeScript, and Go, plus a REST API. Teams can call Blaxel from applications hosted on Vercel, so frontend deployment and hosting stay unchanged. The integration adds an API call rather than an application migration. Teams using Ruby, Java, or Rust reach Blaxel through the REST API, since those languages don't have first-class Blaxel SDKs. Run a small proof of concept before committing production traffic.

What are Vercel Sandbox's session limits?

The default timeout is configurable within each plan's maximum, and the feature comparison table lists those plan limits. Vercel describes total persistent-sandbox lifetime as effectively unbounded through repeated stop and resume cycles. Each resume restores filesystem state rather than memory or processes, and snapshot expiration stays configurable. Blaxel imposes no session ceiling on paying tiers. Its indefinite standby preserves runtime state, though Volumes remain necessary for guaranteed long-term retention on Blaxel.

Which platform is stronger on compliance?

They support overlapping requirements, but their certification lists differ. Blaxel publishes SOC 2 Type II and ISO 27001, with HIPAA available through a Business Associate Agreement add-on. Vercel holds SOC 2 Type 2, ISO 27001:2022, and PCI DSS v4.0. It also offers HIPAA BAAs to Pro and Enterprise customers. Its compliance documentation doesn't publish a separate Sandbox-level scope statement. Confirm the exact scope with each vendor during procurement before committing regulated workloads.