Orbital weapon platforms were powerful structures developed by the Cardassian Union during the Dominion War. They were also in use by the United Federation of Planets and were present in Earth orbit. (TNG short story: "Eleven Hours Out")
Each platform was equipped with three heavy disruptors and a complement of one thousand plasma torpedoes. Their hulls were also protected by regenerative forcefields. The platforms did not have power generators aboard, as they relied on a nearby subspace power generator located on an asteroid-moon. (DS9 episode: "Tears of the Prophets")
After the Bajoran wormhole was blocked by the Prophets and the Romulan Star Empire declared war on the Dominion, several hundred orbital weapon platforms were deployed in the Chin'toka system, to enable more ships to be sent to the Romulan front.
The Federation Alliance had noticed the small ships numbers in the Chin'toka system and Benjamin Sisko had formulated a plan to attack it. The allies later discovered the placement of the platforms and also that they were not operational. Knowing the Chin'toka system was the best place to attack Cardassia from in the future, the plan remained in place and the Allies moved up their departure from Deep Space 9.
When the Allies arrived at the Chin'toka system some time later, they found the platforms still offline. The Jem'Hadar ships there commenced suicide attacks on the Klingon forces, giving the Cardassians time to get the platforms operational. The Starfleet and Romulan ships began firing on the platforms, destroying several before the network was activated. The Allies began to take heavy casualties, with several ships being destroyed or disabled.
The crew of the USS Defiant were able to locate the power source for the platforms and attempted to destroy it, although it proved impenetrable. Miles O'Brien suggested imprinting a Federation warp signature on the power source. His plan was successful and the platforms fired on the moon, destroying the facilities there. The power generator exploded soon after, destroying the moon in the process. With the power source destroyed the platforms were deactivated, allowing the Allies to destroy them and take the system. (DS9 episode: "Tears of the Prophets")
Several orbital weapon platforms were located in orbit of Cardassia in late 2375 and remained under Dominion control after the Cardassians turned on their former allies. They formed part of a large Dominion defense perimeter that the Dominion gathered together after their retreat from the Battle of Cardassia. It was planned for the Federation forces to take on the platforms, although Odo was able to convince the Female Changeling to surrender before the attack was launched. (DS9 episode: "What You Leave Behind", DS9 short story: "Requital")
Ethan Locken and his "New Federation" had obtained an orbital weapon platform by 2376 and had placed it in orbit of Sindorin. As the USS Euphrates approached the planet in that year, the platform fired on the runabout, disabling it. Julian Bashir was later able to take control of it and target the missile Locken had aimed at Orias III. The platform destroyed the missile as it left orbit of the planet. (DS9 novel: Abyss)