What does it do?
It lets you build a regular expression without writing it. Drag blocks written in plain language onto the canvas — starts with, digit, one of, either, repeat 2 to 4 times — and the regex is written for you as you go, with an explanation of every part.
How to use it
- Drag blocks from the palette to the canvas, or tap them to append them.
- Put blocks inside a Group or an Either block to nest them.
- Select a block to change its text, its characters or how many times it repeats.
- Test it right away in Quick test, one case per line.
- Copy it as a literal or export it for JavaScript, TypeScript, HTML
pattern, Zod or Angular.
Undo and redo with the buttons or with Ctrl+Z and Ctrl+Shift+Z.
Example
| Blocks | Regex |
|---|
| Starts with · Digit ×3 · Exact text “-” · Digit ×4 · Ends here | ^\d{3}-\d{4}$ |
| Starts with · Either (“http” / “https”) · Exact text “://” | `^(?:http |
The Share button stores the pattern in the link (after the #), so you can send it to a colleague.
Frequently asked questions
›Can I edit an existing regex visually?
Yes. Paste it in the field above the canvas and press Convert: it becomes blocks you can rearrange. Constructs the builder has no block for, such as lookaheads or back-references, are kept as “Regex code” blocks so nothing is lost.
›Does it work on a phone?
Yes. Tap a block in the palette to add it at the end of your pattern, and use the grip to reorder blocks by dragging.
›Which regex flavour does it produce?
JavaScript (ECMAScript) syntax, which is also valid for the HTML pattern attribute, Zod and Angular. The Python export works for most patterns; named groups use a different syntax in Python.