Regular Expression Tester

Check a regular expression against sample text.

Enable JavaScript for interactive processing. You can read the instructions, limits, and FAQs below without it. Files are processed only in your browser.

Regular Expression Tester User Guide

Test JavaScript regular expressions in a worker and list matches. Processing stays in your browser; review the result before use.

How to use

Enter data and choose options.
Start processing and review the result.
Copy the result or download a new file.

Formats and limits

Each input is limited to 100,000 UTF-16 code units; individual tools have additional format and range limits.
Text is limited to 20,000 and pattern to 1,000 code units. Worker execution times out after 1 second; up to 100 matches are listed.
Processing stays on your device; leaving the page clears the current session.

Output

Displays text that can be copied or downloaded as TXT.

Frequently asked questions

Will the original data be changed?

No. The result is separate; save it before leaving.

The file name and content are only processed in your browser and are not transmitted to the server. The original file will not be overwritten. Please export the required results before leaving the tool.

All tools

Images

Barcode Image Reader
Read one common linear barcode from a still image, showing its format and content.
Animated GIF Maker
Combine same-sized images into an animated GIF in sequence.
Image Art Filters
Apply grayscale, sepia, or inversion and export a PNG.
Image Watermark
Overlay an image or logo in the lower right and export PNG.
QR Code Image Reader
Read one QR Code from a still image and review its text.
HEX Color Converter
Convert a HEX color to RGB and HSL values.
PNG Alpha Mask Exporter
Convert raw PNG alpha values into a grayscale mask: white is opaque and black is transparent.
ID Photo Cropper
Crop a photo for the selected purpose, manually check its composition, and export JPG.
Image Dimension Annotator
Draw dimension lines on an image, enter values and units manually, then export a PNG.
Dual Image Overlay Comparator
Compare two same-size images in shared coordinates using a split view or crossfade.
Seamless Texture Seam Previewer
Use a 3×3 tile and half-size cyclic shifts to move texture boundaries where they are easy to inspect.
PNG Transparent Border Cropper
Precisely trim fully transparent outer rows and columns by alpha while preserving shadows and transparent holes.
Sprite Sheet Player
Preview multiple SpriteSheets in the same frame size, sort, frame by frame, and adjust playback speed.
Sprite Sheet Studio
Arrange frames, preview animations, export to PNG/JPG/BMP, batch ZIP and projects.
Image Converter & Compressor
Convert JPG, PNG, and WebP to and from each other, adjust size and file size.
Screenshot Redactor
Manually frame and crop, and cover sensitive information in screenshots with solid colors.
Image Background Remover
Identify subjects locally, preview and export transparent PNGs.
Image Stitcher
Arrange multiple pictures vertically, horizontally or in a grid to create a new picture.
Text Watermark
Set the text, position and transparency, and export the annotated image.
Image Color Picker
Click on the original image pixel to copy HEX, RGBA or save the color chip.
Rotate & Flip Images
Rotate 90 degrees, flip horizontally or vertically, and export a new copy.
Round Image Corners
Set the corner radius, preserve transparent corners and export as PNG.
Image Grid Slicer
Slice multiple images using a shared grid, custom names and split ZIP files.
Image Information Viewer
Inspect image dimensions, formats and available details in batches.
Color Contrast Checker
Check the WCAG contrast of the text and background solid color code.
Add Image Borders
Add a solid-color border of equal width around the image to retain the original size.

Data

Unix Timestamp Converter
Convert between Unix timestamps and UTC date-times.
Text Base64 Converter
Convert UTF-8 text to or from standard Base64 and Base64URL.
JWT Inspector
Decode JWT header and payload while retaining the JSON text.
Regular Expression Tester
Test JavaScript regular expressions in a worker and list matches.
URL Structure Inspector
Inspect the host, path, and query parameters of an HTTP URL.
Integer Base Converter
Convert integers exactly between bases 2 and 36.
Secure Password Generator
Generate a random password with browser cryptographic randomness.
Secure Random Integer
Draw an integer within a specified range using secure randomness.
IPv4 Subnet Calculator
Calculate the network, mask, and broadcast address for IPv4.
CSV Column Selector
Select and reorder CSV columns, preserving every cell as text in a new copy.
CSV / TSV Converter
Preview the table, retain text and leading zeros, and export a new copy.
JSON Formatter
Indent or compress JSON, preserving numeric precision and field order.
File Base64 Encoder & Decoder
Convert files to Base64 text, or restore text to files.
URL Encoder & Decoder
Convert text to URL element encoding, or restore percent encoding.
UUID Generator
Generate UUID v4 in batches locally, copy or export the list.

Text

Text Case Converter
Convert text to upper or lower case.
Line Whitespace Cleaner
Trim whitespace from each line.
Line Prefix and Suffix
Add a prefix and suffix to each line.
Literal Text Replacement
Replace all case-sensitive literal matches.
Line Numbering
Number lines in input order.
Text List Comparison
Compare two lists to find shared or unique lines.
Text Reverser
Reverse text by Unicode grapheme.
HTML Entity Converter
Escape special characters or decode HTML character references.
UTF-8 Hex Converter
Convert text to UTF-8 bytes or decode valid hexadecimal data.
English URL Slug Generator
Turn English text into a lowercase hyphenated slug.
Text Code Point Viewer
Inspect code points and UTF-16 offsets in logical order.
Markdown Formatter
Organize lists, blank lines, and tables, and retain the original manuscript and content.
Convert Text to UTF-8
Export a copy from UTF-8 or Big5 and check encoding and line breaks.
Text File Merger
Arrange UTF-8 text files, set separation and then merge and export.
Text Statistics
View the number of characters, graphemes, lines, and UTF-8 bytes.
Text Line Cleaner
Remove blank or duplicate lines, sort by clear rules and export.
Text Diff
Compare the two texts line by line to see clearly the differences in additions, deletions and line breaks.

Files

File Hex Viewer
Page through bytes, decimal offsets and ASCII in one file.
ZIP Directory Viewer
Read ZIP central-directory paths and declared sizes, then copy or download a TXT listing.
File Content Comparison
Check the complete file piece by piece to make sure every byte is the same.
Batch File Renamer
Add the prefix and serial number, preview and package it into a renamed copy.
Split Files into ZIP Packages
Divided into independent ZIPs according to capacity, complete delivery list attached.
File SHA-256 Checksums
Batch calculation file summary, copy or export complete checklist.

Audio

WAV Channel Splitter
Split stereo WAV into left and right mono files, preserving every PCM sample.
WAV Audio Trimmer
Cut short WAV audio files, audition, fade and export.
WAV Volume Adjustment
Adjust WAV gain or peak normalization, listen to it and export it.

Video

Video Trimmer
Select the start and end times, re-encode locally and export to WebM.
Video Frame Capture
Move to the specified time and export the current screen to PNG.
Remove Audio from Video
Remove the audio track and re-encode the clip to silent WebM.
Video Contact Sheet
Evenly capture multiple time points to create an overview map with time annotations.
Video Information
View size, duration and size of batches, and export TXT/JSON list.
Separate Video & Audio
Split the video into silent WebM and independent audio, pilot and export respectively.