Regex Tester
Regex Tester reads your regular expression back in plain English, piece by piece, and lights up the matches in your own text or a whole folder of files. Pick your language, from C# to Python, and the matches follow its rules. Preview a replace across every file, then undo it in one click.
Your regex, read back in plain English, with the matches lit up in your own files.
See it in action
About Regex Tester
Regex Tester reads your regular expression back to you in plain English, and shows what it matches as you type.
Read it in plain english
Every piece of your pattern gets a short label under it: "the year", "word edge", "has a digit", "8 or more chars". Hover a piece for the full explanation, groups and lookaheads included. Click the pattern to edit it.
Describe it
Don't want to write it from scratch? Type a few words, like date, email, phone or GUID, and pick from 40 ready patterns for emails, web addresses, dates, times, phone numbers, postcodes, colors, GUIDs, file paths, version numbers and more.
Test it on your own files
Type or paste some text, or drop a whole folder on the window. Every file shows how many matches it has, and the matches light up in the text. Binary files, build and source-control folders, and files over a size you choose are skipped.
Your language, your rules
Regular expressions don't behave the same everywhere. Pick .NET and C#, JavaScript, Python, PCRE and PHP, or Rust, and the pattern is written the way that language writes it. The matches follow its rules too: in C#, Python and Rust, \w also matches accented letters, and in C#, Python and PHP, $ also matches before a final line break. The other four languages each say Same, Differs or Won't compile, with the reason.
Replace across a folder
Type what to replace with and preview every change, file by file, before anything is touched. Then replace in every file at once. Each file is copied first, so Undo puts every one back. Files keep their encoding, and a file changed since you previewed it is left alone.
Copy as code
When it works, copy it as code for C#, JavaScript, Python, PowerShell, PHP or Rust, ready to paste. The replacement is rewritten for that language too.
A pattern that backtracks too much is stopped and flagged rather than freezing the app. Light and dark themes, or match Windows.
Features
- Read any regular expression in plain English: every piece of the pattern gets a short label under it
- Hover a piece for the full explanation of what it matches
- Describe what you want, like date, email, phone or GUID, and pick from 40 ready patterns
- Matches light up as you type, in your own text or across a whole folder of files
- Drop a folder on the window, or choose one, and see how many matches each file has
- Pick your language: .NET and C#, JavaScript, Python, PCRE and PHP, or Rust
- The pattern is written the way your language writes it, and the matches follow its rules, like \w matching accented letters in C#, Python and Rust
- The other four languages each say Same, Differs or Won't compile, with the reason
- Preview every replacement before anything changes
- Replace across every file at once. Each file is copied first, so Undo puts every one back
- Files keep their encoding, and a file changed since you previewed it is left alone
- Copy the pattern as code for C#, JavaScript, Python, PowerShell, PHP or Rust, with the replacement rewritten to match
- A pattern that backtracks too much is stopped and flagged, so the app never freezes
- Skips binary files, build and source-control folders, and files over a size you choose: 1, 4, 16 or 64 MB
- Light and dark themes, or match Windows
Details
- Works on
- Windows 10 (1809 or later) and Windows 11
- Download
- About 3.0 MB
- Version
- 2.0.2, updated October 2026
- First released
- January 2023
- Price
- $1.99 once. No subscription.
- Category
- Developer tools
What's new in 2.0.2
- New: your pattern is read back in plain English, piece by piece
- New: describe what you want and pick from 40 ready patterns
- New: test against a whole folder of files
- New: pick C#, JavaScript, Python, PHP or Rust, and the matches follow that language
- New: preview a replace across every file, then undo it
- New: copy the pattern as code for six languages
- New: light and dark themes
Questions
Anything else? Ask us
Which versions of Windows does it run on?
Windows 10 (version 1809 or later) and Windows 11.
Is it a subscription?
No. Regex Tester is a one-time purchase of $1.99, and updates are included.
How do I get it?
EvlarSoft apps are moving to direct downloads from this site. Ask to be notified and we will email you as soon as Regex Tester is ready to download.
