In 2026, the model is no longer the hard part of shipping an AI agent. Frontier models plan, call tools and operate a computer through a screen, so the work that decides whether an agent survives production has moved underneath it, into the browsers, sandboxes and machines it runs on.
For most teams, buying agent infrastructure is the right call. Building it means owning warm capacity, isolation, browser identity, logins and session recording as a standing system that needs work every week. Build it yourself only when infrastructure is your product or a hard constraint rules out an outside vendor. This guide covers what building takes, when it is worth it, and what buying from Solari changes.
Why Is Build vs Buy the Question of 2026?
Building looks cheap on the first day. Chromium and Playwright are open source, a headless browser runs in any container, and an agent can click through a flow by the afternoon.
The cost arrives with scale. One browser on a laptop becomes thousands that nobody watches, each loading untrusted pages, carrying a login, facing bot checks and failing in ways no one sees. None of that work is the agent itself; it is plumbing between the agent and the web.
That changes the question for an engineering team. The old question was whether you could build it. The new one is whether your senior engineers should spend their quarters keeping browsers alive, or improving the agent only your company can build.
What Does Building Agent Infrastructure Take?
A production agent fleet needs five layers before it does useful work. Each one is buildable, and each one keeps moving after you ship it:
Warm capacity. An agent puts the browser in its request path, so a cold start stalls the whole loop. You end up running a pool of pre-booted browsers, resizing it with traffic through the day and draining sessions before every deploy, because killing a stateful session kills live work.
Isolation. A browser exists to run code nobody vetted, and a page that escapes Chromium on a shared host reaches the sessions beside it. You need one browser per lightweight VM, plus a pipeline that rolls out every Chromium security fix across the fleet within days.
Identity and network. Sites read a browser fingerprint and the IP behind it on every request, and a datacenter address is often blocked before the page loads. Keeping fingerprints coherent, sourcing residential proxies and solving CAPTCHAs is work that drifts every month as detection changes.
Logins that persist. Most valuable agent work sits behind a sign-in. You need a store for cookies and site data that a new session can reopen, and a way for a person to sign in again when a site asks for a second factor.
Observability. An agent that fails halfway through a long task leaves a log line, not an explanation. You need session recordings, a replay tool and retention long enough to debug last week's failure.
Around those five sit the compliance projects: SOC 2 audits, HIPAA controls for healthcare data, and the upkeep each one needs every year. None of it makes the agent smarter.
When Should You Build It Yourself?
Build when the infrastructure is the product, or when a constraint leaves no other choice. These are the real reasons:
Browser infrastructure is what you sell. If your company sells stealth, proxies or a browser platform, the five layers are your roadmap, not overhead. Owning them end to end is the business.
You work behind a hard data boundary. On-premises mandates, procurement rules or data-residency requirements can forbid an outside runtime. When the constraint is real, it outweighs every efficiency argument.
You have spare senior capacity and a reason for control. A large platform team with a deliberate need to control every layer is not wrong to build. It should budget those layers as a permanent product with its own on-call rotation.
Most build decisions are made for none of these reasons. They happen because a demo worked on the first day and the costs showed up later. For a proof of concept, buying is almost always right: ship on a provider, learn the real scope, then revisit the decision with data.
What Role Does Solari Play?
Solari is the infrastructure layer an agent runs on: cloud browsers, sandboxes and desktops from one API. Your team keeps the model and the logic; Solari runs the five layers underneath.
Solari browsers are ready in 8 ms, so your agent never waits on a cold start. With Solari you can launch up to 100,000 browser sessions at once, so there is no pool of your own to size or drain.
Each Solari sandbox is a microVM of its own unless you choose a shared tier, so code your agent writes stays away from your systems and from other sessions. Across companies the isolation holds on every tier: you never share a VM with another organization.
Turn on stealth for sites with bot defenses and add a proxy in the country you choose, with a timezone that matches the IP. Every other site runs on the faster default browser, so you pay for stealth only where a site needs it.
A Solari profile saves your agent's login, cookies and site data, so every later session opens already signed in. Profiles use Playwright's storage state format, so a login you already have uploads as is.
Record a session and replay it in the console, or download it as a line-by-line log your own tools can read. A failed run becomes something you can watch instead of guess at.
Solari can deploy inside your own virtual private cloud on a custom contract. A strict data boundary no longer forces a team to build from scratch.
Browsers are one surface of three. Solari desktops give computer-use agents a full Linux screen to operate, and sandboxes run the code your agent writes, all on one account, one API key and one bill. The launch announcement covers all three. It also costs less: Solari is about 2x cheaper than Browserbase per browser hour, billed per second while an environment runs.
Where Is Agent Infrastructure Going Next?
Over the next year, four changes will raise the cost of building and the value of buying:
Fleets replace single sessions. Teams will move from running one agent at a time to running thousands in parallel on a schedule, and capacity that scales without planning becomes the baseline expectation.
Agents keep state for days. Long-running agents will pause, resume and fork from snapshots instead of starting fresh each time, so infrastructure that keeps memory and processes across a pause becomes standard.
Computer use moves beyond the browser. Agents will operate desktop apps that never shipped an API, which needs a full machine with a screen, not only a browser tab.
Audit becomes a requirement. As agents act under a company's name, buyers will ask to see what each one did, and recordings move from a debugging tool to compliance evidence.
What stays yours is the agent: the model you choose, the prompts and tools, and the judgment about which jobs to hand over. That is the part worth your senior engineers' time.
Get Started With Solari
Start with one workload that already runs on a self-hosted browser, point its Playwright connection at Solari, and compare a week of runs. Solari is the fastest and cheapest way to run cloud browsers and VMs for production AI agents. Get started with a free account and start running your agents today.
