The E2B invoice arrived in the same week the coding agent picked up a new job: checking its own changes in a real browser. At standup, the platform lead asked whether the place where generated code runs was still the right place. Nobody on the team had compared sandbox vendors since the prototype.
A sandbox for agent code is an isolated machine where code a model wrote can run without touching anything else, and E2B is where most teams start. The strongest alternatives are Solari, Daytona, Modal, Vercel Sandbox and Blaxel, and Solari leads the list because it runs sandboxes, cloud browsers and desktops from one account and one API. This guide covers why teams look past E2B, then what each alternative costs and where it fits.
Reasons to Consider an Alternative to E2B
The search for a second vendor usually starts with a limit the team has just hit, so the limits come first. E2B says its Hobby plan is free with a $100 one-time usage credit, sessions up to 1 hour and 20 concurrent sandboxes, on E2B's pricing page. Its Pro plan is $150 a month plus usage, with sessions up to 24 hours and 100 concurrent sandboxes, on the same E2B page.
Three events tend to follow. A long-running agent outgrows the session cap, and E2B places multi-day sessions on Enterprise, which requires a $3,000 monthly minimum, per E2B's plans. A cost review puts the per-second usage line next to other vendors' rates. Or the agent starts needing a browser or a desktop beside its code, and a second vendor enters the stack.
Each alternative answers those events differently, and the table below sorts them before the details.
The Five Alternatives at a Glance
The table gives each vendor's niche in a few words; the sections after it put numbers on each one.
Solari comes first because it answers all three events from the same account.
1. Solari
Solari is the environment an agent runs in: the customer brings the model and the logic, and Solari supplies the machine.
Core capabilities. A Solari sandbox is a Linux machine for agent code with commands, files, Git, snapshots and forks, and by default it is a dedicated microVM of its own behind a hypervisor. The hardened tier blocks all outbound network, and the cheaper shared tier separates a team's sandboxes with Linux namespaces and a cgroup instead. With pause and resume, memory and running processes are kept, so an agent picks up exactly where it stopped.
Beyond sandboxes. The same account opens cloud browsers and Solari desktops, Linux computers with a screen for computer-use models that start "usually in about a second". An agent that writes code, tests it in a browser and checks a desktop app stays on one API key and one bill.
Pricing and plans. Solari's Free plan costs $0 and comes with $3 in monthly credits, and Professional bills sandboxes at $0.0245 per vCPU-hour and $0.0077 per GB-hour, on Solari's pricing docs. Credits refill each month and there is no end-of-month overage charge. The comparison on Solari's pricing page puts Solari almost 3x cheaper per sandbox hour than E2B and Daytona.
Speed. The site says sandboxes are ready in 90 ms. On the pricing page's lifecycle chart, a Solari sandbox runs its full lifecycle about 1.3x faster than E2B and about 1.7x faster than Daytona. An agent that opens a fresh sandbox per task gains that margin on every task.
Who it's best for. Teams whose agents run code and operate the web in the same job, and want one bill for both. Moving from E2B takes one import change, so the comparison can run on a real workload in an afternoon.
2. Daytona
Daytona offers the widest choice of machine types on this list.
Pricing and plans. Daytona says its pricing is usage-based with no monthly plan fee and $200 in free compute to start, on Daytona's pricing page. Compute bills per second at $0.0504 per vCPU-hour and $0.0162 per GiB-hour of memory on the same Daytona page. A team with bursty agent traffic pays for the seconds it runs, with no plan to outgrow.
Where it shines. Daytona offers container, Linux VM, Windows and GPU sandbox classes, per Daytona's sandboxes docs. A team that needs Windows or a GPU for agent work keeps it with one vendor.
Trade-off. Daytona's docs say "Sandboxes run as Linux containers by default", while its VM class is a "Full virtual machine with its own kernel", per its isolation page. A team that wants VM isolation picks that class on purpose. For the browser, Daytona's own post pairs it with Notte, in Daytona runs the code, Notte runs the browser.
3. Modal
Modal comes to sandboxes from serverless compute, and that shows in how it bills.
Pricing and plans. Modal says its Starter plan has no fee beyond compute and includes free credits every month, while Team adds a monthly fee, a larger credit and higher container limits, on Modal's pricing page. The same page says sandboxes are billed per second at non-preemptible rates, a multiple of the list price for its standard functions. A sandbox-heavy workload should be priced on those sandbox rates, not on the headline compute rates.
Where it shines. Modal runs GPU tasks and CPU work on one platform, per Modal's pricing page. A team whose agent also trains or serves a model keeps both jobs on one bill.
Trade-off. Modal is a general serverless platform, so sandboxes are one product among functions, schedules and GPU jobs. An agent that operates a browser or a desktop adds a vendor for that part.
4. Vercel Sandbox
Vercel Sandbox is the option for teams whose apps already deploy on Vercel.
Pricing and plans. Vercel says Sandbox is free on Hobby within monthly quotas, after which sandbox creation pauses until the next cycle, on Vercel's Sandbox pricing page. Pro usage draws on a monthly credit and then bills Active CPU plus provisioned memory, and time spent waiting on network requests or model calls does not count toward Active CPU. An agent that mostly waits on a model pays little for CPU, though its memory bills for the whole run.
Where it shines. Each sandbox is a Firecracker microVM with its own filesystem and network, per Vercel's Sandbox docs. Teams on Vercel add isolated code execution without a new vendor or a new login.
Trade-off. Each plan sets a maximum session duration, and a longer job stops and resumes to continue, since the limit resets on each resume, per Vercel's quotas. Agents built around long sessions need that stop and resume step in their loop.
5. Blaxel
Blaxel is built around agents that sit idle most of the time.
Pricing and plans. Blaxel says its pay-as-you-go plan has no fee beyond usage, comes with up to $200 in free credits, and never counts suspended time toward active CPU, on Blaxel's pricing page. Higher sandbox limits unlock in tiers as an account tops up credits. An agent that waits for events all day costs little beyond the storage that keeps it ready.
Where it shines. Blaxel says sandboxes scale to zero when idle and resume from standby with memory and filesystem intact, on Blaxel's pricing page. Each agent runs in its own hardware-isolated microVM, which suits assistants that wake on a message and answer at once.
Trade-off. Suspended sandboxes keep their state in snapshots billed by storage, so a large idle fleet moves cost from compute to storage. That line deserves its own row in any cost estimate.
Choosing the Right Setup
The choice comes down to what the agent does besides running code and how long it runs. Choose Daytona for Windows or GPU classes, Modal for agents that sit beside model training, Vercel Sandbox for teams already on Vercel and Blaxel for agents that idle for hours. Choose Solari when the agent runs code, browses and uses a desktop in the same job, and when the sandbox bill matters. E2B is the more established sandbox vendor with the larger ecosystem; Solari is the younger company and moves faster on speed and price.
Get Started With Solari
The first step is to move one agent's sandbox to Solari with the import change and run the same task on both vendors side by side. Against E2B and Daytona, Solari is the fastest and cheapest choice for agent code, backed by the lifecycle and sandbox-hour multiples in the Solari section, and it is free to start: create a Solari account and read how Solari started.
