Regex Tester & Evaluator
Test regular expressions in real-time with visual match highlighting, flag toggles (g, i, m, s), replacement preview, and built-in regex presets.
Regex Tester & Evaluator runs 100% in-browser on client devices with zero server latency and zero data transmission. It provides instant output with local privacy.
Quick Regex Presets
How to Use Regex Tester & Evaluator
Step-by-step operating guide
- 1
Type your Regular Expression pattern into the pattern input bar, or select a Quick Preset (Email, URL, IP, Phone).
- 2
Toggle flags (g, i, m, s) and edit your test text payload below.
- 3
View real-time match highlighting, captured sub-groups, and replacement string preview.
Frequently Asked Questions
Technical and usage details for Regex Tester & Evaluator
Are my regex patterns or test strings uploaded to a server?
No. Regular expression evaluation runs 100% locally inside your browser V8 / JavaScript engine.
What do the regex flags mean?
g = Global search (find all matches), i = Case Insensitive, m = Multiline mode (^ and $ match line starts/ends), s = DotAll (. matches newline).
Related Developer Utilities
Markdown Live Editor
Live Markdown editor with split-screen preview and HTML export.
Markdown Previewer
Real-time Markdown to HTML previewer and syntax validator with instant copy.
Markdown Table Generator
Create, edit, and convert spreadsheet tables to GitHub Flavored Markdown (GFM) with column alignments.
JSON Formatter
Format, validate and beautify JSON with syntax highlighting and error detection.
Explore Popular Free Tools
View All ToolsPDF Compressor
Compress and shrink PDF document file sizes 100% in your browser.
Rotate PDF Pages
Rotate PDF pages 90°, 180°, or 270° permanently in your browser with zero cloud uploads.
Delete PDF Pages
Remove unwanted, blank, or duplicate pages from any PDF document client-side.
PDF Splitter & Page Extractor
Extract pages or split PDF files into separate documents 100% in your browser with client-side processing.