regex101 for the terminal — real-time matching, 3 engines, capture groups, replace mode, syntax highlighting, plain-English explanations, undo/redo, mouse support. Written in Rust.
brevity1swos/rgx has 198 GitHub stars.
It currently ranks #39389 daily, #39513 weekly, #40418 monthly by momentum on Trending Repos; its best-ever rank is #4429.