Regex Tester — Free & Private

A free edge API by formatho.com, privacy-first developer tools.

Free, no signup, runs entirely in your browser — your data never leaves your device.

🔓 Free 🔒 Zero tracking 🚫 No data collection ⚡ Edge-fast

Usage

curl "https://regex-tester-formatho.filesformatho.workers.dev/api?pattern=%5Cd%2B&flags=g&text=abc%20123%20xyz"

# Named groups + POST body (recommended for long text):
curl -X POST --data-binary @input.txt \
  "https://regex-tester-formatho.filesformatho.workers.dev/api?pattern=(%3F%3Cyear%3E%5Cd%7B4%7D)-(%3F%3Cmonth%3E%5Cd%7B2%7D)&flags=g"

Parameters

Param	Default	Description
`pattern`	required	The regular expression (max 1,000 chars). Alias: `regex`.
`flags`	`g`	Any of `d g i m s u v y` (global by default).
`text`	`""`	Test text via GET (max 100,000 chars) — or POST the body. Alias: `test`.

Each match returns its index, end, capture groups and named_groups. Invalid patterns return HTTP 400 with the exact parser error.

Live response: /api endpoint.

Privacy-first: every request is processed in-memory on Cloudflare's edge and answered immediately. No logs, no analytics, no cookies, no data collection. Your text and patterns never touch a disk.

What it handles

Global and non-global matching, capture groups, named groups ((?<name>…)), all standard flags including s (dotAll) and u/v (Unicode), and up to 1,000 matches per request with a truncated flag when the cap is hit.

Full browser tool

Prefer a UI with live highlighting? Use the complete client-side version — your data never even leaves your browser: Regex Tester on formatho.com.

All Formatho edge APIs

Browse every free Formatho Worker tool on the Formatho Tools index.