goreplay

GoReplay is an open-source network monitoring tool designed to record live HTTP traffic and reuse it for testing purposes. It supports traffic shadowing, load testing, monitoring, and detailed analysis by listening on network interfaces in the background, which avoids placing a third-party component in the critical path. The tool can capture traffic from a specified port and either output it for inspection or replay it against a staging environment. A basic setup uses commands such as `sudo ./gor --input-raw :8000 --output-stdout` for traffic capture and `sudo ./gor --input-raw :8000 --output-http http://staging.env` for replay. GoReplay is distributed as pre-built binaries and can also be compiled from source. The project offers documentation, a FAQ, troubleshooting guides, and community support through GitHub issues and a Google Group. A commercial PRO extension adds support for binary protocols like Thrift and Protocol Buffers, cloud storage save/replay, and TCP session replication. The README lists several organizations using the tool, including GOV.UK, the Guardian, and TomTom.