Authors including Robert Harris, Joanne Harris and Jilly Cooper have condemned an app which allows users to cover up swear words in eBooks.
The newly-launched Clean Reader program hides all explicit and rude words in novels in eBook format and replaces them with tamer alternatives.
Chocolat novelist Joanne Harris has decried it as a form of censorship.
"Writers of fiction choose their words (including what you refer to as profanities) very carefully," she said in a scathing blog post.
"To enable a writer's work to be modified without permission, then for you claim that nothing much has been altered, is to completely misunderstand the nature of fiction writing."