Strain relief devices for electrical connectors are disclosed and include an insert for insertion into a housing. The insert may include spring beams that deflect during insertion into the strain relief housing. When the insert is fully received in the housing, a slot in the housing may be shaped such that the spring beams return to a relaxed state, locking the insert in the housing. Alternatively, an end of a strain relief insert may be inserted into the housing until beams on the strain relief insert abut shoulders in the slot in the housing. The end may protrude beyond the housing, creating a tab that may be deformed or bent to prevent the insert from moving in a direction opposite the direction of insertion.