Founded in 1996,[4] Stamps.com was created under the name StampMaster by Jim McDermott, Ari Engelberg, and Jeff Green, who at the time were MBA graduate students at UCLA.

[5][6] StampMaster was among the first companies to obtain approval from the United States Postal Service for beta testing and introducing Internet postage to the market.

[8] It had its last round of private financing in February 1999,[9] generating an additional $30 million[8] from investors including former Postmaster General, Marvin Runyon.

[18] It acquired Auctane ShipStation, a web-based multi-carrier shipping vendor based in Austin, Texas, in June 2014 for $50 million and up to 768,900 shares of stock.

[20] In October that same year, Stamps.com acquired ShipWorks, a multi-carrier shipping software company that integrates with shopping cart platforms, for $22 million.

[24] On July 25, 2018, Stamps.com announced another agreement to purchase Metapack Ltd., a London-based company providing delivery management technology to e-commerce retailers and brands.

MetaPack will continue to operate as a wholly owned subsidiary led by its current management team with further details of the acquisition to be discussed on August 1, 2018.

[29] Stamps.com allows users to print official United States Postal Service stamps and shipping labels for a monthly subscription fee of $19.99.

[30] Stamps.com sends customers a digital scale to weigh letters and packages to ensure the correct amount of postage is applied to the piece of mail.

[31] Stamps.com also offered a product called PhotoStamps that allows customers to upload personal photographs or logos to be printed on real U.S. postage stamps.

[37] Stamps.com settled a $2.5 million consumer protection lawsuit from the State of California in 2015 over free trials that eventually converted into monthly service fees.