Question 1

What is a Regular Expression (Regex)?

Accepted Answer

A regular expression (Regex) is a sequence of characters that defines a search pattern used to find, match, or manipulate text. For example, \d+ matches one or more digits, [A-Z] matches any uppercase letter, and (foo

Question 2

Is my data sent to a server?

Accepted Answer

No data is ever sent to a server — this tool runs 100% client-side using JavaScript in your browser. Your text, search pattern, and replacement string are processed entirely on your device and never transmitted over the network or stored in any database. This makes the tool safe for sensitive content such as API keys, passwords, private emails, proprietary source code, or personal documents. Closing or refreshing the tab clears everything instantly.

Question 3

Can I use this for normal find and replace without Regex?

Accepted Answer

Yes, you can use plain text search without Regex by leaving the 'Use Regex' option unchecked. In that mode the tool performs a standard string search, matching the exact characters you type in the Find field — the same behavior as find-and-replace in a word processor or text editor. You can still combine plain text search with the Case Sensitive and Global Match toggles, giving you control over whether the match is case-insensitive and whether all occurrences or just the first are replaced.

Question 4

What does Global Match do?

Accepted Answer

When Global Match is enabled (the default), every occurrence of your search pattern in the text is replaced. When it is turned off, only the very first match is replaced and all subsequent matches are left unchanged. This toggle maps directly to the global flag (g) in JavaScript's RegExp syntax. Global Match is the right choice for bulk replacements like renaming a variable throughout a file; turning it off is useful when you want to correct only the first instance while leaving deliberate later uses intact.

Question 5

What does Case Sensitive do?

Accepted Answer

When Case Sensitive is off (the default), the search ignores letter case — searching for 'hello' also matches 'Hello', 'HELLO', and 'hElLo'. When turned on, the match is exact and 'hello' will only match the lowercase form. This setting corresponds to the presence or absence of the case-insensitive flag (i) in JavaScript's RegExp engine. Case-insensitive matching is ideal for natural-language text where capitalization varies; case-sensitive matching is better for source code where 'null' and 'Null' are distinct values.

Question 6

Can I use capture groups and backreferences?

Accepted Answer

Yes. When Regex mode is enabled, you can use capture groups — parentheses like (\w+) — to capture parts of the matched text, then reference them in the replacement field using $1, $2, and so on. For example, if your Find pattern is (\w+),\s*(\w+) and your Replace field is $2 $1, the tool will swap the order of two comma-separated words. This is one of the most powerful features of JavaScript's RegExp engine and enables complex reformatting tasks that would be impossible with plain text search.

Question 7

What is the difference between Replace and Replace All?

Accepted Answer

Replace All substitutes every occurrence of your pattern in the text at once, while Replace changes only the first match found, regardless of the Global Match setting. Replace All is the most common choice for bulk edits — for example, renaming a function across a code snippet or fixing a recurring misspelling throughout a document. Replace is useful when you want to change only one specific instance. Both buttons use the same Find pattern and Replacement value you have entered in the fields above.

Pattern	Matches
\d+	One or more digits
[A-Z]+	Uppercase letters
\s+	Whitespace / tabs
\b\w+\b	Whole words

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Common Regex Patterns

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Frequently Asked Questions

Common Regex Patterns

Why Use This Tool?

How to Use It

Frequently Asked Questions

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