useonlinetools

Regex tester

free online regex tester — right in your browser, no uploads, no sign-up, instant results.

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Regex testing runs locally — your test data never leaves your browser.
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how to use

How to use this tool

1

Upload your files

Drop files onto the page or select them from your device. They're read locally — nothing leaves your browser.

2

Configure options

Adjust any settings or preferences for how you want the tool to process your files.

3

Process

Click the action button and the work is done in your browser — no waiting for server uploads or downloads.

4

Download your result

Save the processed file straight to your device. No watermarks, no sign-up, no limits.

about this tool

Free Online Regex Tester without giving up your privacy

Building regular expressions is iterative — you tweak a pattern, test it against real data, tweak again. A server-side regex tester would mean sending your test data (which could be logs, code, emails, or PII) over the network with every keystroke. This tester runs entirely in your browser using JavaScript's native RegExp engine. Matches highlight in real time as you type, capture groups are listed individually, and all standard flags (g, i, m, s, u, y) are supported. Your test text never leaves your browser — perfect for debugging regex patterns against production logs, customer data, or proprietary code.

Privacy by design. This tool loads once and runs entirely in your browser tab. Close the tab and nothing remains. No cookies, no tracking, no server — just the utility you need, instantly.

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faq

Frequently asked questions

No. All processing happens entirely inside your browser. Your files are read locally, processed in your device's memory, and handed back as a download — nothing is transmitted anywhere.
No. There's no sign-up, no email, and no paywall. Open the tool, process your files, and download — that's the entire flow.
No fixed cap. Because everything runs locally, the practical limit is your device's available memory. Most people process files up to hundreds of megabytes without any issue.
Yes. Once the page loads, the entire tool runs in your browser and works without an internet connection — perfect for planes, secure environments, or anywhere with limited connectivity.
No. The tool preserves your files exactly as they are. No quality loss, no compression artifacts, no modification unless you explicitly choose to apply changes.

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