API load testing without writing scripts

What a load test is

A load test applies the traffic you expect on an ordinary busy day and holds it there. Users ramp up over a short period, stay at that level for the bulk of the run, and ramp back down.

It is the test to run first and the one to run often. Where a smoke test proves the flow works and a stress test finds the breaking point, a load test answers the question you are actually asked in a planning meeting: will this be fine on Monday?

When to run one

• Before a release that changes anything on a hot path.
• When traffic is forecast to grow — model the number you expect, not the number you have.
• On a schedule against staging, so a regression shows up as a changed p95 rather than as an incident.

What to read in the report

p95 response time

The number most service-level agreements are written against. A p95 that climbs while throughput stays flat means queueing somewhere.

Error rate

Anything above zero under expected traffic is a finding, not a rounding error.

Requests per second

If this stops rising while users keep arriving, you have found a ceiling — worth a stress test next.

Running one in Stabula

Build the request in the editor — URL, headers, auth, body — choose Load Test, and the settings below are filled in for you. Change any of them; the load profile under them redraws, and the estimate says what the run will cost against your month's allowance before you start it.

The run itself happens in an isolated container on our infrastructure, not in your browser, and the report is written in sentences rather than percentiles alone: which targets were met, which checks failed, and what the runner hit — grouped by cause and host.