The Outsiders (not to be confused with the Korian Outsiders) operate a number of space stations in each system. The Outsiders are scrupulously neutral. Everyone is welcome at their stations - citizens, militia, pirates, or aliens - regardless of affiliation or reputation. Unlike other factions, the Outsiders don't operate any space ships, just stations.
Because of the Outsiders' neutrality, it's not unusual to encounter hostile ships in the vicinity of their stations.
The Outsider stations offer missions from all factions, although Citizenry and Militia missions are the most common. Be sure to check how each offered mission would affect your reputation with the various factions.
The Outsider stations don't offer exactly the same ship types for sale as Citizenry stations do. They offer two of the Red Devil ships (the Icarus and the Barracuda corvettes) but don't offer the Tennhausen frigate, Vanguard heavy frigate, or McKinley cruiser.
The Outsider stations offer the Smuggler's Hold and some additional defensive equipment that the Citizenry stations don't: Field Impact Shields (regular shields aren't offered) and the Rebound and Ramming Deflectors.