Every regex tester shows you matches. The questions that matter are whether your pattern leaves the browser and whether it explains itself.
| Capability | jsonversal | regex101 / RegExr | Online evaluators (eval sites) |
|---|---|---|---|
| Runs client-side | Yes | Yes | Varies |
| Works on private input | Yes — patterns and text never leave the tab | Yes | Check before pasting secrets |
| Explains the pattern | Yes — tokens and groups described | Yes | Usually just results |
| Flavour selection | JavaScript & Python | JavaScript, PCRE | Varies |
| Match groups / indices | Yes | Yes | Yes |
| Pattern presets | Common patterns included | Yes | No |
For interactive learning, regex101 has the better live editing. For a pattern that contains customer data, an internal routing rule, or anything you would not paste into a chat window, a client-side tester with explanations is the safer choice — you can see what each group does without sending the text anywhere.