k6 vs Gatling: Which Load Testing Tool for CI?
Both are code-first load testers; k6 uses JavaScript and is lightweight, while Gatling uses Scala/Java with high-throughput simulations and rich reports.
k6 (Grafana) is a Go-based load tester scripted in JavaScript, optimized for low resource use and CI. Gatling is a JVM-based tool with Scala (or Java/Kotlin) DSL simulations, known for high throughput and detailed HTML reports.
| k6 | Gatling | |
|---|---|---|
| Scripting language | JavaScript | Scala / Java / Kotlin DSL |
| Runtime | Go (lightweight) | JVM |
| Reporting | CLI + Grafana | Rich HTML reports |
| CI fit | Excellent (thresholds) | Good (CLI, reports) |
| Best for | Developer-owned JS tests | JVM teams, high throughput |
In CI
k6 is lighter and uses JavaScript, which lowers the barrier for developers and keeps scripts close to the app code; thresholds make CI pass/fail clean. Gatling delivers high throughput and excellent HTML reporting and fits teams comfortable with the JVM and Scala/Java DSL. Both run from CI; the choice often follows team language preference and reporting needs.
Run it in CI
Gate on performance thresholds so regressions fail the build, and run heavy simulations on capable runners. Load generation is resource-heavy; larger, faster managed runners produce more load per runner and finish big scenarios sooner.
The verdict
Want lightweight, JavaScript, CI-native load tests: k6. Want high throughput, rich reports, and a JVM DSL: Gatling. Gate on thresholds in CI and size runners to the load you need to generate.