TOOL SIGNAL / ACTIVE

tcpkali

Machine Zone

Protocol/API Load Open Source Self-hosted

Frequently asked

Is it open source?

Yes. tcpkali is listed as open source.

What protocols does it support?

tcpkali supports TCP, WebSocket.

Is it cloud or self-hosted?

tcpkali is listed as self-hosted.

Is it still maintained?

tcpkali is listed as active.

tcpkali creates large numbers of TCP or WebSocket connections and messages. It is designed for protocol-level capacity and connection testing.

About

tcpkali is a high-performance TCP and WebSocket load generator and sink designed to stress-test and benchmark network systems. It can operate in client mode (generating traffic to specified hosts) or server mode (accepting connections and discarding data).

Features

  • Opens millions of connections from a single host using interface aliases
  • Efficient multi-core operation using all available cores by default
  • Bandwidth-controlled traffic generation for upstream and downstream throughput
  • Customizable message patterns (first and subsequent messages)
  • Latency percentile measurement using HdrHistogram
  • Stats reporting to StatsD/DataDog

Pricing

Open source and free (no pricing information found)

Author / Company

Originally developed at Machine Zone (author Lev Walkin), the project is now maintained at https://github.com/launchdarkly/tcpkali.

Latest release

1.2.0 (as referenced in historical man pages)

Sources

GROUNDED VIA EXA · 2026-08-11

Signal notes

License
Open Source
Deployment
Self-hosted
Pricing
Free; BSD 2-Clause License.
First released
2015
Scripting
C
Protocols
TCP, WebSocket
Operating systems
Linux, macOS
Tags
websocket · tcp · connections
Official site ↗ Source repo ↗