regex101 vs The Regex Coach

regex101 is an online workspace for building, testing and debugging regular expressions. Its editor supports PCRE2, JavaScript, Python, Golang, Java,.NET 10.0, Rust, POSIX ERE, POSIX BRE and legacy PCRE. Explanations show how parts of a pattern match according to the selected flavor, and a step-through debugger helps follow matching. Match results can be exported as JSON, JSON Lines, CSV or plain text. Developer options include HTTP APIs, an MCP server, editor links and a separately licensed parser package. The workspace API stores editor data but does not provide a remote matching endpoint. File loaders read text, bytes and supported documents locally in the browser; saving or sharing workspace input can send it to the workspace service. Free includes core tools, one test string and saved workspaces with an account. Pro costs €4.99 a month, billed yearly, and adds multiple test strings, substitution pipelines, advanced benchmarking, formatting and an ad-free workspace. Enterprise is a self-hosted option with documented deployment on Linux using Docker Compose, MySQL and Redis.

The Regex Coach is a graphical application for experimenting interactively with Perl-compatible regular expressions. It shows whether a pattern matches a target string and updates the interface when changes are made. Users can highlight captured groups or selected parts of a pattern in the target text. The application can attempt a plain-English explanation of a regex, show its parse tree graphically, and step through the matching process. It also simulates Perl split and substitution operations. Written in Common Lisp, it uses CL-PPCRE as its regex engine. The current Windows download is version 0.9.2; the maker says the program has not changed since 2008. Linux is no longer maintained, though an unsupported 0.8.5 release is available and also runs on FreeBSD. There is no Mac version planned. The program is provided as-is without warranty, and the maker says not to expect support for older Windows configurations or the unsupported Linux release. The engine may overflow its stack with relatively long regular expressions. The listed plan is free, with conditions for commercial use and redistribution.