A former editor at The New Republic revealed in a lengthy essay published late Wednesday that she had started the online list of men in the media industry accused of sexual harassment.

The editor, Moira Donegan, said she created the Google spreadsheet in October to allow women in the media industry to put in writing what many of them had long discussed in private: the names of men to stay away from, including sexual harassers and abusers. Within hours of its creation, the list grew beyond her expectations, as women shared it with friends and co-workers who anonymously added new names and new accusations.

“What was going on there was clearly cathartic for the women who were using it, telling their stories, encouraging one another, saying that it had happened to them too,” Ms. Donegan, 28, wrote on New York magazine’s website The Cut.