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12.0K Stars 848 Forks Apache License 2.0 288 Commits 141 Opened issues


HTTP load generator, ApacheBench (ab) replacement, formerly known as rakyll/boom

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hey is a tiny program that sends some load to a web application.

hey was originally called boom and was influenced from Tarek Ziade's tool at tarekziade/boom. Using the same name was a mistake as it resulted in cases where binary name conflicts created confusion. To preserve the name for its original owner, we renamed this project to hey.


  • Linux 64-bit:
  • Mac 64-bit:
  • Windows 64-bit:

Package Managers

macOS: - Homebrew users can use

brew install hey


hey runs provided number of requests in the provided concurrency level and prints stats.

It also supports HTTP2 endpoints.

Usage: hey [options...] 

Options: -n Number of requests to run. Default is 200. -c Number of workers to run concurrently. Total number of requests cannot be smaller than the concurrency level. Default is 50. -q Rate limit, in queries per second (QPS) per worker. Default is no rate limit. -z Duration of application to send requests. When duration is reached, application stops and exits. If duration is specified, n is ignored. Examples: -z 10s -z 3m. -o Output type. If none provided, a summary is printed. "csv" is the only supported alternative. Dumps the response metrics in comma-separated values format.

-m HTTP method, one of GET, POST, PUT, DELETE, HEAD, OPTIONS. -H Custom HTTP header. You can specify as many as needed by repeating the flag. For example, -H "Accept: text/html" -H "Content-Type: application/xml" . -t Timeout for each request in seconds. Default is 20, use 0 for infinite. -A HTTP Accept header. -d HTTP request body. -D HTTP request body from file. For example, /home/user/file.txt or ./file.txt. -T Content-type, defaults to "text/html". -a Basic authentication, username:password. -x HTTP Proxy address as host:port. -h2 Enable HTTP/2.

-host HTTP Host header.

-disable-compression Disable compression. -disable-keepalive Disable keep-alive, prevents re-use of TCP connections between different HTTP requests. -disable-redirects Disable following of HTTP redirects -cpus Number of used cpu cores. (default for current machine is 8 cores)

Previously known as

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