testssl.sh

testssl.sh is a free, open-source command-line tool designed to check a server's service on any port for the support of TLS/SSL ciphers, protocols, and some cryptographic flaws. It is distributed under the GPLv2 license and is 100% open source, allowing users to inspect the code and understand exactly what is being tested. Key features include clear, easy-to-read output that indicates whether findings are good or bad, as well as machine-readable output formats including CSV, two JSON formats, and HTML. The tool requires no installation or configuration—no gems, CPAN, pip, or similar package managers are needed. It works out of the box on Linux, macOS, FreeBSD, NetBSD, WSL2, MSYS2/Cygwin, and OpenBSD, provided bash version 3.2 or higher and standard tools like sed and awk are available. Windows users can run it via MSYS2, Cygwin, or WSL/WSL2. A Dockerfile is provided, and official container builds are available on Docker Hub and GHCR, supporting multiple architectures including linux/amd64, linux/386, linux/arm64, linux/arm/v7, linux/arm/v6, and linux/ppc64le. The tool is flexible enough to test any SSL/TLS-enabled and STARTTLS service, not limited to web servers on port 443. Several command-line options allow users to configure their tests and output formats. Privacy is a core design principle: only the user sees the results, with no third-party involvement. The project is actively developed on GitHub with unit tests ensuring consistency, valid JSON output, and cross-platform compatibility on Linux and macOS. The current development branch is 3.3dev, evolving from the 3.2 stable release, with the project supporting n-1 versions. Documentation is available in groff, HTML, and Markdown formats in the repository's doc directory, as well as on the official website at testssl.sh. The project welcomes contributions, including bug reports, documentation improvements, unit testing, and GitHub Actions enhancements. Related external projects include web frontends, mass scanners with parallel scanning and Elasticsearch integration, Nagios/Icinga plugins, Excel report generators, and GitHub Actions integrations.