In 2026, agents no longer stop at suggesting code. They write it, run it and open websites on their own, and every one of those steps needs an isolated machine, a sandbox, so the agent's code never touches your production systems.
Solari and Vercel Sandbox both give your agent that machine as a microVM started by API. Solari starts faster, costs less per sandbox hour and adds cloud browsers and desktops on the same account; Vercel Sandbox fits best when your app already deploys on Vercel. This comparison covers speed, price and the jobs each one fits.
Why Does Agent Code Need Its Own Machine?
Agent code needs its own machine because nobody reviews it before it runs. A coding agent clones a repository, installs packages, runs the tests and retries until they pass, and a team runs hundreds of those loops at once. Any of that code can be wrong or unsafe, so each run belongs in a machine you can throw away or pause afterwards.
Vercel built Sandbox for this job and made it generally available as a compute layer for agent code. Solari runs the same kind of isolated machine next to browsers and desktops. The choice comes down to three questions: how fast a machine starts, what an hour of it costs and what else your agent needs to do.
Solari vs Vercel at a Glance
Which Is Faster, Solari or Vercel?
Solari is faster on every number either company publishes. Solari browsers are ready in 8 ms, so an agent that starts a fresh browser for every task spends almost none of its run waiting. Vercel says its sandboxes "start in milliseconds" and publishes no start time to compare against.
For browser work, Solari measures the whole run, not only the start. On Steel's open-source benchmark, a Solari session averages 199.9 ms end to end, create to release, across 5,000 runs; the pull request with those results is open, so you can rerun it yourself.
A Solari desktop, a full Linux computer with a screen, starts usually in about a second. You get a live view of it from the moment it is created.
Which Costs Less to Run?
Solari costs less per sandbox hour at list price. Solari bills per second while an environment runs, and its lowest published rate for a 4 vCPU, 8 GB sandbox is $0.114 per hour. At list price, the same machine on Vercel Sandbox comes to $0.683 per hour in Solari's comparison.
Vercel bills a different way. Vercel Sandbox charges for active CPU, the time the processor is actually busy, plus provisioned memory for as long as the sandbox runs. An agent that spends most of its time waiting on a model pays less for CPU than the list comparison suggests, while memory bills for the whole session either way.
Solari handles idle time with pause. Pause a sandbox and its memory and processes are saved; resume it and your agent picks up exactly where it stopped, and a paused machine stops counting against your plan's limit on running machines. You can start on a free account and pay only once your agents run at volume.
What Can You Run on Each?
Both run agent code in an isolated microVM. The difference shows up once an agent needs more than a terminal:
Coding agents. Both Solari and Vercel run a coding agent's clone, install and test loop in a fresh machine. On Solari you can snapshot and fork a sandbox, so many attempts start from one prepared state instead of reinstalling dependencies each time.
Code from your customers. A product that runs customer scripts needs strict isolation. Solari's dedicated isolation gives each sandbox a microVM of its own, and hardened isolation blocks all outbound network, so the code cannot call out at all.
Web tasks behind a login. An agent that files a form or checks a portal needs a real browser. Solari cloud browsers work with Playwright and keep a sign-in between runs with profiles, so your agent logs in once.
Computer use. Models with computer use operate software through a screen, clicking and typing like a person. A Solari desktop gives that model a full Linux computer with a mouse, a keyboard and a live view you can take over.
Long-running agents. Some agents work for hours and wait for long stretches in between. Vercel says its persistent sandboxes save state on stop and resume where they left off; Solari pauses an idle machine automatically and brings it back exactly as it was.
What Role Does Solari Play?
Solari is the infrastructure your agent runs on: cloud browsers, sandboxes and desktops from one account and one API. Your agent brings the logic; Solari gives it a place to work.
A clean machine for every task. Because machines start fast, you can give each task its own fresh environment. Nothing carries over from one run to the next unless you choose to keep it.
Code, web and screen together. Your agent can run code in a sandbox, then open a browser to check the result, without a second vendor or a second bill. The SDK ships as separate packages for browsers, sandboxes and desktops under one API key.
Isolation you pick per sandbox. Choose dedicated isolation for a microVM of your own or hardened isolation to cut the network. You set it at create time, per sandbox.
Fleets, not single machines. With Solari you can launch up to 100,000 browser sessions at once, so a job that covers thousands of sites runs in one pass.
Solari's own marketing system runs in a Solari sandbox. The launch announcement covers how the three surfaces fit together.
Where Are Agent Sandboxes Going Next?
Over the next year, a fresh machine for each step of an agent's work becomes the default, and more agents will write code and then test it in a browser in the same run. Computer-use models will operate apps that never shipped an API, and long-running agents will pause between steps instead of rebuilding their state.
What stays human is deciding what an agent may touch and reviewing what it ships.
Which Should You Choose?
On speed, Solari publishes its start times and its full browser run; Vercel describes its start as milliseconds without a number. On price, Solari's lowest published sandbox rate sits well under Vercel Sandbox's list price for the same machine, while Vercel's active CPU billing narrows the gap for agents that mostly wait. On fit, Solari puts sandboxes, browsers and desktops on one account.
Choose Solari when your agents need fast, cheap sandboxes plus browsers or desktops in one place. Stay on Vercel Sandbox when your app already deploys on Vercel and your agents only run code: its project authentication and active CPU billing fit that setup well. 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 running your coding agent's test loop in a sandbox, then add a browser when the agent needs the web. Solari is the fastest and cheapest way to run cloud browsers and VMs for coding and web agents. Get started with a free account and start running your agents today.
