明信片软件是一个近似共享软件的软件发行形式，用户在使用时会看到提醒消息向软件开发者发送一张明信片（或是邮票等收藏品）以示谢意。

这形式亦与啤酒软件相近。「电邮软件」作用相同，不过开发者会要求用户发送一封电子邮件。

明信片软件通常不会强制要求用户发送明信片后才可使用该软件。

Postcardware, also called just cardware, is a style of software distribution similar to shareware, distributed by the author on the condition that users send the author a postcard.

A variation of cardware, Emailware, uses the same approach but requires the user to send the author an email. Postcardware, like other "novelty" software distribution terms, is often not strictly enforced.