Volunteer

Fits when affectionate teasing is clearly welcome

Careful Do-gooder is often dismissive or sarcastic and can insult the person being thanked.

Fits when belonging to the working group matters more than pay status

Careful Crew member can be paid and says nothing about freely offered service.

Fits when the role is informal and the practical assistance matters most

Careful The label leaves voluntary or unpaid status unknown.

Fits when backing a cause is more important than the specific task

Careful A supporter may only endorse or donate and never volunteer time.

Fits when practical service in a neighborhood is the focus

Careful Community worker often implies paid employment, so it should not silently replace volunteer.

Fits when time, expertise, money, or material is added to a shared effort

Careful A contributor may be paid, donate money, or author material without volunteering time.

Fits when taking part matters without claiming a service role

Careful Participants may receive the benefit themselves and need not be helping others.

Fits when spontaneous help to a stranger deserves moral warmth

Careful The phrase has a biblical origin and does not fit organized recurring service.