Vegeta is an HTTP load testing tool and library designed to measure the performance and stability of web services. It functions as a command-line utility, a programmable package for integration into other applications, and a distributed load generator capable of splitting request rates across multiple machines.
The tool is distinguished by its constant-rate request scheduler, which dispatches requests at a fixed frequency regardless of target response times. It employs lazy target streaming to maintain low memory usage during large tests and uses a binary-encoded storage format to minimize disk I/O during high-throughput execution.
Beyond request generation, it provides a performance analysis toolkit for evaluating request latency, success rates, and throughput. This includes the ability to generate text histograms, JSON reports, and interactive HTML time-series plots. The system also integrates with Prometheus and Grafana by exposing real-time metrics via an HTTP endpoint.
Target definitions can be managed through structured schemas, plain text files, or dynamic streaming inputs.