Find and Replace Text (with Regex)
What This Tool Does
This find and replace tool searches any text for a target string or regex pattern and replaces it with a new string. Options include case-sensitivity, whole-word matching, regex mode, and match counting. Useful for cleaning data, refactoring content, or bulk editing documents.
Inputs Explained
- Source Text: The text you want to search within.
- Find: The string or regex pattern to search for.
- Replace With: The string to substitute. Leave blank to delete matches. Use $1, $2 for regex capture groups.
- Case Sensitive: When checked, only exact-case matches are replaced.
- Whole Word: Match whole words only, not substrings (ignored in regex mode).
- Regex Mode: Treat Find as a JavaScript regex pattern (without the slashes).
How It Works
The tool builds a JavaScript RegExp from your input (escaping special characters if regex mode is off), applies appropriate flags (g for global, i for case-insensitive), and uses String.replace to perform the substitution. It also counts matches before replacing so you can preview the change count.
Formula / Logic Used
Find and replace text instantly with regex, case, and whole-word options.
Step-by-Step Example
Source: The cat sat on the mat. Another cat was there too.
Find: cat | Replace: dog | Whole word: ✓
Result: The dog sat on the mat. Another dog was there too.
Regex example: Find (\d{4})-(\d{2})-(\d{2}), Replace $3/$2/$1 converts YYYY-MM-DD dates into DD/MM/YYYY format across the entire text.
Use Cases
- Content editing: Quickly fix a typo or brand name change across a long document.
- Code refactoring: Rename a variable or function across pasted code snippets with whole-word matching.
- Data cleanup: Standardize phone number formats, date formats, or address fields using regex capture groups.
- SEO audit: Find every occurrence of an old URL to update in bulk content export.
- Email personalization: Replace placeholders like {FirstName} with real values before sending.
Assumptions and Limitations
- Regex mode uses JavaScript regex syntax, which differs slightly from Python or PCRE (no lookbehind variations in older browsers).
- Very large inputs (>5 MB) combined with complex regex patterns may slow the browser significantly.
- Whole-word matching uses \b word boundaries, which treat hyphens and apostrophes as word breaks.
- The tool does not support step-by-step replacement preview — all replacements happen at once.
Frequently Asked Questions
How to find and replace text online
Paste your text into the input box, type the word or phrase you want to find, then type what it should be replaced with. Hit Replace All and the tool swaps every match in one go. Use the preview to check before copying — particularly useful if you're cleaning up a long document or fixing a name spelling across hundreds of lines. There's a copy button for the cleaned-up output, so you can move it back into your Word doc, email, or code editor.
How to replace multiple words in a text file
Two ways. The simplest is to run Find and Replace once per word — paste your text, swap the first pair, hit Replace All, then repeat for the next word without leaving the page. The faster way for big batches is regex mode, where you can match a whole pattern at once like (cat|dog|bird) and replace them all with a single rule. Always preview before copying, especially when you're stacking multiple replacements one after another.
How to use regex to replace text online
Switch on regex mode. Then your search field accepts patterns instead of plain text — \d+ matches any number, \s+ matches any whitespace, [A-Z]+ matches uppercase letters, and so on. The replace field can use $1, $2 for captured groups. Test on a small sample first because a wrong pattern can rewrite more than you intended. Start with simple patterns and build up; the preview shows the result before you commit, so you can catch mistakes early.
How to remove text between two characters regex
Use a non-greedy pattern like \(.*?\) to remove anything between parentheses, or \[.*?\] for square brackets. The ? makes the match non-greedy, so it stops at the first closing character instead of grabbing everything until the last one. Replace with empty to delete, or with your own text to substitute. Always preview the result — greedy patterns are the most common reason people accidentally wipe out half their document in one click.
How to replace line breaks with spaces online
Switch on regex mode and use \n (or \r\n for Windows-style line endings) in the find field, then put a single space in the replace field. Hit Replace All. Your text collapses into a single line. Useful for cleaning up text copied from a PDF where every line break makes the paragraph awkward to work with. If you need to keep paragraph breaks, replace \n\n first with a placeholder, do your single-line clean-up, then put paragraph breaks back.
How to replace commas with new lines in text
Type a comma in the find field. In the replace field, switch on regex mode and use \n to insert a newline. Run Replace All. Your comma-separated list — like "apple, banana, mango" — splits into separate lines: apple, then banana, then mango. Works the other way too: replace \n with ", " to flatten a list back into a comma-separated row. Handy for moving data between spreadsheets and plain-text fields without manual editing.
How to do case sensitive find and replace
Switch on the case-sensitive toggle (it's usually unchecked by default). Now searching for "apple" only matches "apple" and ignores "Apple" or "APPLE". Without it on, the tool treats all three as the same word. Useful when you're working with code variables, brand names, or anything where capitalisation has meaning. Programming languages care about case, so leave the toggle on when you're refactoring variable names. Turn it off when you're cleaning prose.
Sources and References
- MDN — Regular Expressions — Comprehensive JavaScript regex reference.
- MDN — String.prototype.replace — The core replace method used by this tool.
- Regex101 — Test and debug regex patterns interactively.
- ECMAScript Specification — RegExp — Official regex syntax specification.
Related Calculators
What this tool does
Find and Replace Text (with Regex) turns the visible inputs on the page into a specific result and keeps the calculation context close to the form. The added notes identify what the output means, which assumptions matter, and when the result should be checked against source data or official guidance.
How to use this tool
- Enter the values requested by the form, keeping units, formats, and date fields consistent.
- Run the calculation or conversion and review each output label before using the result elsewhere.
- Compare important results with the page notes, examples, or official references when accuracy affects money, safety, configuration, or reporting.