# ApacheBench (ab) — Benchmark Web Servers from the Command Line > Practical guide to ApacheBench (ab) — HTTP load tests, concurrency, Keep-Alive, POST data and TLS benchmarks on the command line. Source: https://www.jpkc.com/db/en/cheatsheets/networking/ab/ ApacheBench is the classic HTTP load-testing tool from the Apache project: a single command fires hundreds or thousands of requests at a web endpoint and instantly returns throughput, response-time percentiles and error counts. It ships on any system with apache2-utils installed – ideal for a quick smoke test after a deployment or a first-pass stress check before a traffic spike. This guide covers the most-used options, from a basic GET benchmark to HTTPS and POST-JSON testing. ## Basic Benchmarks `ab -n -c ` — Run a benchmark with specified requests and concurrency. ```bash ab -n 1000 -c 10 http://localhost:8080/ ``` `ab -n 100 ` — Simple benchmark with 100 requests (1 concurrent). ```bash ab -n 100 http://localhost/ ``` `ab -t -c ` — Benchmark for a fixed duration instead of request count. ```bash ab -t 30 -c 50 http://localhost:8080/ ``` `ab -k -n -c ` — Use HTTP Keep-Alive (persistent connections). ```bash ab -k -n 5000 -c 100 http://localhost:8080/ ``` ## POST & PUT Data `ab -p -T ` — Send POST data from a file. ```bash ab -p data.json -T 'application/json' -n 100 -c 10 http://localhost:8080/api ``` `ab -u -T ` — Send PUT data from a file. ```bash ab -u update.json -T 'application/json' -n 50 http://localhost:8080/api/item ``` `ab -p -T 'application/x-www-form-urlencoded' ` — POST form data. ```bash ab -p form.txt -T 'application/x-www-form-urlencoded' -n 100 http://localhost/login ``` ## Headers & Authentication `ab -H '
' ` — Add a custom HTTP header. ```bash ab -H 'Authorization: Bearer token123' -n 100 http://localhost:8080/api ``` `ab -H 'Accept: application/json' ` — Set Accept header for API requests. ```bash ab -H 'Accept: application/json' -n 100 http://localhost:8080/api ``` `ab -A : ` — Use HTTP Basic Authentication. ```bash ab -A admin:secret -n 100 http://localhost/admin/ ``` `ab -C '' ` — Send a cookie with requests. ```bash ab -C 'session=abc123' -n 100 http://localhost/dashboard ``` ## SSL & Proxy `ab -n -c https://` — Benchmark an HTTPS endpoint. ```bash ab -n 1000 -c 20 https://example.com/ ``` `ab -f ` — Force a specific SSL/TLS protocol. ```bash ab -f TLS1.2 -n 100 https://example.com/ ``` `ab -X ` — Use a proxy server. ```bash ab -X localhost:8888 -n 100 http://example.com/ ``` ## Output & Reporting `ab -v ` — Set verbosity level (1=warnings, 2=headers, 3+=body). ```bash ab -v 2 -n 10 http://localhost:8080/ ``` `ab -g ` — Export results as TSV (for gnuplot). ```bash ab -g results.tsv -n 1000 -c 50 http://localhost:8080/ ``` `ab -e ` — Export percentile data as CSV. ```bash ab -e percentiles.csv -n 1000 -c 50 http://localhost:8080/ ``` `ab -r ` — Don't exit on socket receive errors. ```bash ab -r -n 5000 -c 200 http://localhost:8080/ ``` `ab -s ` — Set maximum seconds to wait for a response (default 30). ```bash ab -s 60 -n 100 http://slow-api.example.com/ ``` ## Conclusion ApacheBench is not a replacement for full-featured load-testing frameworks – but for a quick smoke test after a deployment or an early indicator of performance regressions it is unbeatable in its simplicity. If you need percentile charts, HTTP/2 support or more realistic load profiles, take a look at `wrk` or `h2load`. ## Further Reading - [ab – official Apache documentation](https://httpd.apache.org/docs/current/programs/ab.html) – reference and all options - [ab(1) – manual page](https://manpages.debian.org/stable/apache2-utils/ab.1.en.html) – every flag at a glance - [ApacheBench – Wikipedia](https://en.wikipedia.org/wiki/ApacheBench) – background and history ## Related Commands - [wrk](https://www.jpkc.com/db/en/cheatsheets/networking/wrk/) – modern HTTP benchmarker with Lua scripting for realistic load profiles - [siege](https://www.jpkc.com/db/en/cheatsheets/networking/siege/) – HTTP/HTTPS load tester with URL lists and session support - [h2load](https://www.jpkc.com/db/en/cheatsheets/networking/h2load/) – benchmarking tool designed for HTTP/2 and HTTP/3