Add Errors to ASCII simulates controlled corruption by applying selected damage operations to an ASCII string. It is intended for testing parsers, validators, import routines, checksums, and error handling rather than for preserving the source exactly.
The tool can insert, delete, or replace characters. Each operation is local to the string, and the resulting output is still kept visible so you can compare the original and damaged forms. The number of requested errors is a target rather than a guarantee that every operation produces a unique visual change.
Randomized damage is useful when you need many imperfect test cases. A deterministic seed is provided so a particular test fixture can be reproduced later; leaving the seed blank uses normal browser randomness.
Start with a short sample and one error at a time. Then increase the count and compare how different damage types affect length and character frequencies. Insertions increase length, deletions reduce it, and replacements keep length constant.
The tool intentionally stays within ASCII for its generated damage characters. It does not claim to reproduce real transmission faults statistically; it is a practical test-data generator for software robustness.
Processing remains local. Save a damaged sample when you need a repeatable fixture, and keep the original input separately so failures can always be traced back to the intended source.