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Load Testing GraphQL over HTTP

2 min read
Loadcurl
Loadcurl
Loadcurl Team

GraphQL usually rides on HTTP POST (sometimes GET). That means you can load test it with any HTTP load tool — including Loadcurl — as long as you send the right URL, headers, and JSON body.

There is no separate GraphQL protocol mode in Loadcurl today (and no gRPC/WebSocket tester). Treat GraphQL as HTTP.

What to put in the request​

Typical shape:

POST /graphql
Content-Type: application/json
Authorization: Bearer STAGE_TOKEN

{
  "query": "query HeroName { hero { name } }",
  "variables": {}
}

Validate once in Postman/curl, then paste into New test. Verify the hostname first.

GraphQL-specific pitfalls under load​

1. HTTP 200 with errors in the body​

Many GraphQL servers return 200 even when errors is populated. Your load report may show a healthy 2xx rate while clients are failing. Check response samples / request results, and monitor app-level error metrics.

2. Over-fetching hides the real hotspot​

A single “simple” query can fan out to many resolvers and services. p99 may reflect the heaviest resolver, not the gateway.

3. Persisted vs ad-hoc queries​

Ad-hoc queries stress parsing and planning differently than persisted queries in production. Match what you actually ship.

4. N+1 resolver patterns​

Load tests that only hit a tiny entity look fine until a list field explodes. Include representative list queries in a separate test.

5. Auth and complexity limits​

Complexity/depth limiters and per-token rate limits often show up as 429 or GraphQL errors before CPU saturates.

How to structure Loadcurl tests​

Because each test is one HTTP request under a load profile:

  • Test the hottest query alone first
  • Add a second test for a mutation path
  • Use smoke → load ladders like REST
  • Compare PDFs when you change dataloader / caching / indexes

Pass criteria ideas​

  • Target RPS sustained
  • Gateway + resolver p95/p99 under budget (from APM)
  • Transport error/timeout rates low
  • Application-level GraphQL error rate under budget (not only HTTP 2xx)
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