Find dates and rewrite them
Pattern (?<year>\d{4})-(?<month>\d{2})-(?<day>\d{2}) with the g flag finds both dates. The replacement $<day>/$<month>/$<year> uses the named groups:
Invoice 2026-10-07, due 2026-11-06.Invoice 07/10/2026, due 06/11/2026.- Home
- Developer tools
- Regex Tester
Regex Tester
See every match highlighted as you type, with numbered and named groups and a live replacement preview.
Free, no sign-up. Runs in your browser: nothing is uploaded.
How to use Regex Tester
- Enter a pattern and flags.
- Paste the test text.
- Inspect matches or try a replacement.
Features
- Live highlighting
- Capture and named groups
- Flags g, i, m, s, u, y
- Replace with $1 and $<name>
Private by design
Everything you type is calculated by your browser on this device. Nothing is sent to openWorkstand or anyone else, so the Regex Tester is safe for private and work data, and it keeps working offline once the page has loaded. How local processing works
When to use the Regex Tester
- Validate an email address pattern.
- Extract data from log files.
- Test a find-and-replace pattern.
Examples
Troubleshooting
It matches only the first result
Add the g (global) flag. Without it, JavaScript stops after the first match.
My pattern works here but not in Python or Java
This tester uses JavaScript regular expressions. Most syntax is shared, but lookbehind, named groups and flags differ slightly between languages.
Frequently asked questions
Is my data uploaded anywhere?
No. This tool runs entirely in your browser. Nothing you type or open is sent to a server, so it is safe for private and work data, and it keeps working offline once the page has loaded.
Step-by-step guides
- How to test a regexBuild and debug JavaScript regular expressions with live highlighting, capture groups, flags and replacement previews, plus patterns for everyday tasks.
Keep working with the result
openWorkstand also includes a free workspace with documents, spreadsheets, tasks, projects and a calendar that save to a folder on your computer.
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