Endicia is an internet postage service provider based in Mountain View, California.

Endicia was founded as a technology consultant known as PSI Associates by Harry Whitehouse, Amine Khechfé, and Scott Montgomery in Palo Alto, California.

One of PSI's earliest customers was the USPS, to develop a solution that would print the POSTNET (Postal Numeric Encoding Technique) barcode used to sort and process mail directly on an envelope.

On July 2, 2007, Newell Rubbermaid announced the acquisition of Endicia as part of its foray into "innovative technologies and solutions around the world".

In March 2015, Stamps.com entered into an agreement to acquire Endicia from Newell Rubbermaid for approximately $215 million.