(covers information from several alternate timelines)
A portable transporter was a portable site-to-site transporter device that allowed beaming from one location to another without using a large external transporter pad or system. Some were known to be rather large and bulky, while more advanced models were small hand-held devices or miniature models that could be worn on clothing. Some portable transporters had the ability to transport themselves along with the payload.
In 2259, in the alternate reality, John Harrison was in possession of a bulky portable transwarp beaming device, a type of portable transporter. He used it to beam himself from Earth to Qo'noS. The device itself did not beam along with Harrison, but remained behind and was found and recovered from the wreckage of his craft. (Star Trek Into Darkness)
In 2371, Commander Benjamin Sisko theorized that Morka, Atul, and Bo'rak used a portable transporter to place a piece of surveillance equipment in a bulkhead. However, Constable Odo did not believe the Klingon Intelligence personnel would be seen walking through Deep Space 9's corridors with a large device such as a portable transporter. (DS9: "Visionary")
In 2372, in an alternate timeline, Tom Paris had acquired a hand-held site-to-site transporter. He and Harry Kim used the device to transport from a San Francisco street to Harry's office at Starfleet Headquarters and from the office to the Earth Spacedock. This type of transporter beamed itself along with the transported personnel. (VOY: "Non Sequitur")
In 2374, Captain Janeway used a portable site-to-site transporter to escape from Tau, an interstellar pirate in the Delta Quadrant, who had stolen the device from the USS Voyager. (VOY: "Concerning Flight")
In 2375, the Borg drone One developed internal transporter nodes based on the 29th century mobile emitter technology. These implants could be utilized as a personal portable site-to-site transporter. (VOY: "Drone")
In 2379, emergency transport units, a type of miniature portable transporter technology, had been developed by Starfleet. They were designed to provide a single one-direction transport for one individual. During the Battle of the Bassen Rift, Jean-Luc Picard beamed from the Scimitar to the USS Enterprise-E using such a device. (Star Trek Nemesis)