Add Typos to ASCII creates synthetic typing mistakes in ASCII text using a small US-QWERTY neighborhood map. It is intended for testing search, spell-check, form validation, fuzzy matching, and interfaces that need to tolerate imperfect human input.
Common typo operations include replacing a character with a nearby keyboard key, swapping adjacent characters, deleting a character, and inserting a nearby key. The goal is not to model every human typing pattern; it is to create predictable classes of realistic-looking errors.
A seeded option makes a particular typo fixture reproducible. Without a seed, the tool uses browser randomness. Start with a short sentence so you can see exactly which mistakes were introduced before increasing the number of typos.
The tool only introduces ASCII replacements and keeps the source text unchanged. It can change the output length for insertions and deletions, while swaps and replacements keep the length the same.
Keyboard-neighborhood testing is useful when an application compares exact ASCII strings but should be tolerant of ordinary typing mistakes. It should not be treated as a spell checker, language model, or realistic probability model of a person's typing behavior.
All processing happens locally. Save generated typo cases as fixtures when a parser or search algorithm needs a repeatable collection of imperfect input.