API Load Testing

Know your API's limits before your users hit them

Simulate thousands of concurrent API consumers with realistic request distributions, authentication, and dynamic payloads.

Challenges you face

Unknown throughput ceiling

You don't know how many requests per second your API can handle before latency degrades or errors start.

Untested authentication paths

Token refresh, OAuth flows, and session management add latency that never gets measured under load.

Endpoint-level blind spots

Load is applied uniformly, but in production some endpoints are hit 100x more than others.

How perfscale helps

REST, GraphQL & gRPC

Test any HTTP-based API. Parameterise headers, bodies, and query strings per virtual user.

Dynamic scripting

Use k6 or Locust to write realistic user flows: authenticate, read data, mutate state, verify responses.

Rate limiting validation

Test that your rate limiter behaves correctly at 1x, 2x, and 10x expected load.

Error scenario testing

Inject bad payloads, expired tokens, and malformed requests to validate error handling under load.

Continuous contract testing

Run API load tests on every deploy to catch regressions in response time and error rate.

Per-endpoint metrics

Break down p95 latency and error rate by endpoint to pinpoint exactly where bottlenecks occur.

What you get

  • Supports REST, GraphQL, gRPC, and WebSocket
  • Parameterise requests with real data sets
  • Simulate authenticated user sessions
  • Measure cold-start vs warm-cache performance
  • Validate rate limiting and throttling behaviour
  • Test pagination and cursor-based endpoints
  • Catch N+1 query regressions under load
  • Export results for API SLA documentation

Find your API's breaking point before launch

Set up your first API load test in minutes — no infrastructure required.

Get in touch