regex101 vs RegexRegex

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.

RegexRegex is a free browser-based tool for building and testing regular expressions. Its checker runs JavaScript patterns in the browser and shows matches, captures, explanations, and errors, with previews for replacement text. A guided builder composes basic JavaScript patterns using controls for character types, quantities, groups, boundaries, and flags. It can test the pattern it creates, but does not cover every syntax feature or convert arbitrary patterns into an equivalent visual layout. Python, PHP, Java, .NET, and Perl engines can be used by explicitly pressing Run, which sends checks to an online execution service. Replacement previews recognize numbered and named captures such as $1 and $. The searchable reference covers 25 syntax and flag items. Users can save up to 50 test cases in the browser, each with input up to 20,000 characters. Share links include the selected pattern, engine, flags, and operation; test and replacement text are omitted unless users opt in. A cached JavaScript checker may work offline, while checks using other engines need the online service.