RegEx Visualizer & Explainer vs Retest

RegEx Visualizer & Explainer is a browser tool for testing and debugging regular expressions. As a pattern is entered, it highlights matches and shows match and capture-group details. The tool explains individual tokens and provides a step-by-step debugger. Test mode checks pattern matches, Replace mode previews substitutions, and Diff mode compares two patterns. Test cases, presets, a cheatsheet, and browser history are also included. Matching uses the browser’s JavaScript RegExp engine and supports its regex flags. Testing runs in the browser; the page says content stays on the user’s device unless they copy or download a file. The tool runs on the web without installation or an account, and the Free plan costs nothing. It does not provide a multi-language code export panel, so patterns should be retested for differences in a target language. ToolsViewer describes its collection as intended for developers, students, designers, and other professionals. Support requests can be sent by email, with replies targeted within a few business days.

Retest is a free, open-source terminal utility for developing and checking regular expressions on Linux. A subject string can be supplied as an argument or piped through standard input, so it can fit into shell workflows. Retest finds all non-crossing matches and highlights nested capture groups in colors distinct from the whole match. An optional formatted list shows match order and string indexes. Release 0.2.2 added a flag for reading the subject from a file. The project provides Linux release binaries, including a 64-bit Debian installer listed for release 0.2.2. Its README describes compiling from source with Cargo and installing through a Makefile. The source code and documentation are licensed under Apache License 2.0. The project presents Retest as a terminal-based alternative to regex101, for developers building and checking patterns. No paid plans or usage limits are listed.