A needleless connector includes a housing having a housing passage with an open end, a slider disposed in the housing passage, and a mechanism to bias the slider toward the open end of the housing passage. The connector may also include a seal at the open end of the housing passage, the seal either cooperating with the slider to seal the open end of the connector, or sealing the open end of the connector without interaction with the slider, for example taking the form of a slit septum.