Unionized staffers at New York Times Co. ’s product-review website Wirecutter say they have gone on strike due to a contract stalemate with the paper’s management.

Wirecutter staffers plan to strike through Nov. 29, which is Cyber Monday—a popular online shopping day that comes days after Black Friday. The period is Wirecutter’s busiest and most profitable of the year, according to Nick Guy, the Wirecutter Union unit chair and a senior staff writer for the site.