The finance lead pasted the compute line into the agent team's channel on a Tuesday with a short note: why is this growing faster than the work? The coding agents had spent the month inside machines sized for the heaviest build, and most of those hours went to waiting on the model. Somebody replied with the obvious next question: where would the same work cost less?
The cheapest sandbox for AI agent code is the vendor with a low rate at the machine size the agent really needs, plus settings that stop the meter when the agent goes quiet. At list price that is Solari, which runs sandboxes next to browsers and desktops from one account and is almost 3x cheaper per sandbox hour than E2B and Daytona on its pricing comparison. This guide compares how Solari, E2B and Daytona bill, what each free start covers, and the settings that keep the bill small.
How Each Vendor Bills a Sandbox
The first thing to compare is the unit on the meter, because the three vendors do not price in the same one. Solari bills a sandbox by its size, a rate per vCPU-hour plus a rate per GB-hour of memory, and the Professional plan charges $0.0245 per vCPU-hour and $0.0077 per GB-hour. Daytona says it bills $0.0504 per vCPU-hour and $0.0162 per GiB-hour of memory, calculated per second, on Daytona's pricing page.
The chart puts the vCPU rates that are published per hour on one scale.
E2B prices in a different unit. E2B says it charges per second of a running sandbox, at $0.000056 per second for a 4 vCPU machine on its Hobby and Pro plans, on E2B's pricing page, so it sits beside the chart rather than on a converted bar. A fair test runs the same machine size on all three vendors, which is why the entry terms matter as much as the rate.
Solari vs E2B vs Daytona at a Glance
Rates are half of the cost; the other half is what a team commits to before the first sandbox runs. The table sets the entry terms side by side.
Each entry point suits a different shape of team. Solari's Free plan costs nothing and carries $3 in monthly credits that refill each month, and Starter costs $20 a month with the fee returned as credits. E2B says its Hobby plan is free with a $100 one-time usage credit, and its Pro plan is $150 a month plus usage, on E2B's pricing page. Daytona says it has no plan fee and includes $200 in free compute, on Daytona's pricing page.
For the buyer, Daytona offers the largest starting credit, while Solari offers a fixed monthly ceiling. At a zero balance, new Solari sandboxes stop launching until credits arrive, so there is no end-of-month overage charge. With the entry terms settled, the next question is what an hour costs on the plan a production fleet would run on.
What a Sandbox Hour Costs on Solari
Production fleets rarely stay on a free plan, so the useful figure is the hourly cost at a real size. A 4 vCPU, 16 GB sandbox on Solari Professional costs $0.221 an hour. Solari Team costs $0.114 an hour for that CPU count with 8 GB of memory and a 20 GB disk, and Enterprise $0.0114 for the same machine on a custom contract.
The Team figure is the basis of the multiple in the introduction, so a team comparing vendors at list price should compare at that machine size. Solari Professional runs 10 sandboxes at once and Team 50 or more, which decides the plan before the rate does.
Light jobs have a cheaper option still. Solari's shared isolation tier is cheaper and starts faster: the sandbox runs as a process tree inside a VM shared with the team's other shared sandboxes, separated by namespaces and a cgroup. The default dedicated tier gives each sandbox a microVM of its own, a small virtual machine behind a hypervisor. Rate and tier set the price of an hour; the settings below decide how many hours get billed.
Settings That Keep the Bill Small
The bill in the opener came from idle hours, and idle hours are a setting, not a rate. Every Solari sandbox takes an idleTimeoutMs at create time, and with the default lifecycle: { onTimeout: "pause" } it pauses once that time passes with no activity. Sandboxes share their lifecycle with Solari VMs, where a paused machine stops counting against the plan's limit on running machines.
Size is the second setting. A sandbox defaults to 2 vCPUs and 2 GB, accepts 1 to 8 vCPUs and up to 16 GB, and a request above those limits is rejected with a 400 rather than quietly reduced. Starting at the default and moving up only when a job measures slow keeps every hour priced at the small end.
Stored state is the third. Solari bills a stored snapshot at $0.05 per GB-month after the first 10 GB across the organization, and deleting one stops its charges the same day. Those three settings, together with the rates above, are enough to pick a vendor for the next batch of jobs.
Choosing the Right Setup
Following the definition in the introduction, the decision comes down to the size an agent needs, the entry terms a team can commit to and the idle rule it sets. Choose Daytona when the largest starting credit matters, and E2B when the team already builds on its SDK and wants per-second billing. Choose Solari when the sandbox bill matters most and the agent also needs a browser or a desktop from the same account. 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
Start with the job from the opener: create a sandbox at the default size with a pause rule and run a week of agent work on it. Solari is the cheapest of the three at list price, as the multiple above shows, and the fastest too: Solari is about 1.3x faster than E2B and about 1.7x faster than Daytona over a sandbox's full lifecycle. Create a free Solari account to begin, and see the wider field in the E2B alternatives guide.
