Create Mistakes in a String
Introduce random typos by substituting characters in a string. Runs entirely in your browser, so your data never leaves your device.
0 chars · 0 lines
Output
The result appears here as you type.
How to use Create Mistakes in a String
- 1. Paste the clean text. Enter the correct text you want typos introduced into, from a single sentence to a longer passage.
- 2. Set the number or percent of mistakes. Enter a fixed Number of mistakes to introduce, or set Or percent of characters to a nonzero value to scale the typo count with the length of the text instead.
- 3. Copy the text with typos. Copy the corrupted text and use it wherever you need realistic-looking mistakes, such as testing a spell checker or building fake handwritten-style content.
When to use Create Mistakes in a String
Create Mistakes in a String introduces random typos by substituting characters in a string. It is a controlled way to corrupt clean text for testing or demonstration, rather than manually mistyping words by hand.
- Testing a spell-checker or autocorrect feature. You are building or QA-testing a spell-checking feature and need sample text with a known number of injected typos to verify the checker flags them correctly.
- Generating training data for typo correction. You are building a dataset to train a typo-correction model and need pairs of clean and corrupted text with a controlled percentage of character errors.
- Simulating noisy OCR or handwriting output. You want text that mimics the kind of errors OCR software or messy handwriting recognition produces, to test how a downstream system handles imperfect input.
- Making a deliberately imperfect placeholder message. A design mockup needs realistic-looking user-generated content, complete with a few typos, rather than pristine placeholder copy that never looks like real typed text.
Examples
Add typos
Input
hello world
About the Create Mistakes in a String tool
Create Mistakes in a String does its work locally, right in the browser. Introduce random typos by substituting characters in a string. There is no upload step, no queue and no account, and your data never travels over the network.
It belongs to the String Tools collection on EditSafely, a set of 159 small, focused String utilities that share the same instant, private workspace.
You can shape the output with 2 settings, including Number of mistakes and Or percent of characters (0 = use count), and the result refreshes the moment you change one. A worked example further down the page shows exactly what the tool produces for a real input.
Running locally also makes the tool fast and dependable: results appear as you type or drop a file, there is no server outage that can take it down mid-task, and confidential data can be processed without a second thought.
Frequently asked questions
Is Create Mistakes in a String free to use?
Yes, it is completely free. All 2,658 tools on EditSafely work without an account, a subscription or usage limits.
Is it safe to paste sensitive or confidential data?
Everything happens locally. Your browser downloads the tool's code once, then does all the processing itself; nothing you enter is transmitted, stored or logged. You can even go offline after the page loads and it will still work.
How much text can I process at once?
There is no fixed limit. Because the work happens on your own device rather than on a shared server, the practical ceiling is your machine's memory, which comfortably handles inputs far larger than typical online tools allow.
Do I need to sign up or install anything?
No. The tool works in any modern browser on desktop, tablet or phone. There is no account to create, no extension to add and no software to install.
How do I use the result?
The output panel has a one-click copy button, and you can keep refining the input while you work; the result updates in place as you type.