The most useful AI agents of 2026 run the code they write. Coding agents open a terminal, install packages and execute their own output, and every one of those runs needs a sandbox that keeps untrusted code away from your systems and your data.
Vercel Sandbox is one of the newer options: each sandbox is a Firecracker microVM with its own filesystem and network. The best Vercel Sandbox alternatives for AI agents are Solari, E2B, Daytona and Modal. Solari leads for teams that want fast, low-cost sandboxes plus cloud browsers and desktops on one account; E2B, Daytona and Modal each fit a narrower job. This guide compares all four on features and pricing.
Key Takeaways
Choose Solari when your agents need sandboxes that start fast and cost less, plus browsers and computer-use desktops from the same API.
Choose E2B when you want a well-known code-interpreter SDK and a generous free start for short tasks.
Choose Daytona when you need GPU or Windows machines next to your Linux sandboxes.
Choose Modal when your agents already run inference or batch jobs on Modal's serverless GPUs.
Why Look for a Vercel Sandbox Alternative?
Most teams start looking when their agents outgrow the job they first built. These are the four triggers that come up most often:
The agent needs more than a shell. A coding agent that also signs in to websites or operates desktop apps needs browsers and screens next to its sandbox. Buying those from a second vendor means a second bill, a second API key and a second place to debug.
Sessions run for hours. Vercel bills sandboxes on active CPU and charges provisioned memory for the whole run, idle time included. That suits short bursts; an agent that holds a machine open while it waits on a model pays for memory the entire time.
State has to survive. Agents that stop mid-task, wait for a person and pick up later need pause, resume and fork as everyday operations, not workarounds. The cost and speed of those operations decide how a long task feels.
The fleet gets wide. When one agent fans out into dozens of parallel attempts, start time and lifecycle time decide how long the whole job takes, and the per-hour rate decides what it costs.
1. Solari
Solari is agent infrastructure from one API: sandboxes, cloud browsers and desktops on one account and one bill. You bring the model and the agent logic; Solari gives it an isolated machine to run in.
Core capabilities. A Solari sandbox is an isolated Linux machine for agent-generated code: run commands, execute Python that keeps its state between calls, read and write files, and snapshot and fork. By default each sandbox is a microVM of your own, and the hardened tier blocks all outbound network for the code you trust least. You size each sandbox from 1 to 8 CPUs and up to 16 GB of memory.
Speed. A Solari machine usually starts in about a second, so an agent that fans out into parallel attempts doesn't sit waiting on boot. Short start times add up when a single task creates and tears down hundreds of machines.
State that survives. Pause a sandbox and its memory and processes are saved; resume it and your agent picks up exactly where it stopped. Stop it and only the files stay. Fork a running sandbox to try several fixes from the same starting point and keep the one that passes the tests.
Pricing. Solari starts free with $3 of monthly credits, and its self-serve sandboxes bill from $0.0245 per vCPU-hour and $0.0077 per GB-hour. With Solari you can run up to 100,000 sandboxes or desktops at once, so a whole fleet of agents works side by side. Solari is almost 3x cheaper than E2B and Daytona per sandbox hour and runs a sandbox's full lifecycle about 1.3x faster than E2B.
Browsers and desktops on the same account. Solari profiles keep a browser login between runs, so your agent signs in once and every later session reopens the same cookies. Solari desktops give computer-use models a full Linux screen to operate. Your agent can run code, sign in to a website and drive an app with no API, all without a second vendor.
Who it's best for. Platform teams running coding, research or computer-use agents in production who want sandboxes, browsers and desktops from one vendor, priced for fleets rather than single runs.
2. E2B
Pricing and plans. E2B's Hobby tier is free with a $100 one-time usage credit, 1 hour sessions and 20 concurrent sandboxes, while Pro is $150 a month plus usage with 24 hours sessions, 100 concurrent sandboxes and the default 2 vCPU sandbox at $0.000028 a second. Enterprise is a custom contract with multi-day sessions and a monthly minimum, so a long-running workload moves into a sales conversation.
Where it fits. E2B suits agents that run short code-interpreter tasks, such as data analysis, test runs or chart generation. Its SDK is widely known among agent builders, and the free credit covers a long prototyping phase.
Trade-off. Session length is tied to the plan. An agent that works across days needs E2B's custom contract, which adds a negotiation before the workload can run.
3. Daytona
Pricing and plans. Daytona is pay-as-you-go with $200 in free compute to start, vCPU at $0.0504 an hour and memory at $0.0162 per GiB-hour, billed per second. Daytona also rents GPUs at preemptible and on-demand rates. There is no monthly plan fee to plan around, and volume terms go through sales.
Where it fits. Daytona offers four sandbox classes: container, Linux VM, Windows and GPU. Daytona runs sandboxes as Linux containers by default, while its VM classes give a full virtual machine with its own kernel and support pause, resume, fork and hot snapshots. That range suits teams whose agents need Windows apps or GPU work beside ordinary code runs.
Trade-off. The default class is a container. If you want hardware-level isolation for untrusted code, choose a VM class explicitly and price it accordingly.
4. Modal
Pricing and plans. Modal bills sandboxes per second at its non-preemptible rates, with monthly credits included on every plan, and a 4 vCPU, 8 GB Modal sandbox comes to $0.761 an hour at public list price in Solari's vendor comparison. That is the highest sandbox rate of the four options here, so Modal makes most sense when the rest of your compute already runs there.
Where it fits. Modal is a serverless platform for GPU and CPU workloads, and its sandboxes sit next to the functions and GPUs your team already deploys. It fits agents that run model inference, evaluations or data pipelines in the same place they run generated code.
Trade-off. Sandboxes are one feature of a broad compute platform. A team that only needs isolated machines for agent code pays Modal's non-preemptible rate class for every sandbox.
What Comes Next for Agent Sandboxes?
Today most agents use a sandbox for one task at a time. Over the next year that changes in four ways:
Sandboxes that wait for people. Agents will pause for approval and resume hours later with their memory intact, so pause and resume become as routine as create.
Fork by default. An agent will try several fixes in parallel from one snapshot and keep the one that passes, which makes lifecycle speed a daily cost.
Code plus a screen. Models that operate software through a display will move between a sandbox and a desktop inside one task.
Isolation as policy. As prompt injection moves from research to real incidents, teams will default to microVMs and blocked egress for any code an agent did not write under review.
What stays human is judgment: which tasks an agent may run unattended, what it may reach on the network, and what ships. The teams that win will spend their engineers there and hand the machines to agents.
Which Vercel Sandbox Alternative Should You Choose?
Choose Solari over Vercel Sandbox when your agents run for hours, fork often or need a browser and a desktop beside the code, and when sandbox cost and start time matter at fleet scale. Choose E2B for short interpreter tasks with a large free start, Daytona when GPUs or Windows machines are part of the job, and Modal when your agents already live on its GPU platform.
Stay on Vercel Sandbox when your app and team already run on Vercel and your agents execute short bursts of code. Vercel is the more established platform with the larger developer ecosystem; Solari is the younger company and moves faster on speed and price.
Get Started With Solari
Start with one job, such as moving your test-runner agent into a Solari sandbox, then fork it across your backlog once it runs cleanly. Solari is the fastest and cheapest way to run cloud browsers and VMs for coding agents. Get started with a free account and start running your agents today.
