How many concurrent bots or virtual users can Loadster run?

Loadster runs two main kinds of bots (also sometimes called “virtual users”), and they scale differently:

• Protocol Bots are lightweight HTTP clients, so they scale the biggest. Concurrent Protocol Bot capacity on the Loadster platform goes well into the millions.
• Browser Bots and Playwright bots each drive a real headless Chrome browser, which takes far more compute per bot. The biggest real browser test Loadster customers have run on the platform used more than 170,000 concurrent Chrome browsers.

Neither number is a hard limit in Loadster itself. Bots run on managed cloud infrastructure across your choice of cloud regions on AWS and GCP, so the practical scale of any single test comes down to how many bots you allocate to each region and how much instance capacity the cloud providers have available at launch time (see cloud capacity for how Loadster estimates this). In our biggest load tests to date, the constraint was cloud instance availability, not a limit in the Loadster platform itself.

For perspective, most production load tests run between a few hundred and a few thousand concurrent bots, which is plenty to model peak traffic for the vast majority of websites, web applications, and APIs. But even if you need 100K+ real browsers or a million protocol-level users for a huge product launch, a ticket on-sale, a Black Friday or Superbowl rehearsal, rest assured the platform has been there before.

You can also mix bot types in a single test to get browser realism on your critical flows and protocol-level volume everywhere else.

Real Browser Limits on Other Load Testing Platforms

Protocol-level virtual user numbers get advertised loudly across the industry, but real browser limits are rarely published.

Among the competing platforms that do document them (at the time of writing):

• Grafana Cloud k6 caps browser virtual users at 1,000 per test on paid plans.
• BlazeMeter’s documentation caps browser-based performance tests at four users per load engine.
• LoadNinja’s self-serve plans top out at 500 virtual users.
• LoadView mentions an architectural ceiling of 225,000 browser users, with standard accounts limited to 5,000, but does not say how many browsers have actually been run in practice.

As far as we know, no other platform has publicly documented a real browser load test at Loadster’s 170,000+ browser scale.

At least several platforms support protocol-level virtual users into the millions, as Loadster does.