Keys may be formed for keyboards. The keyboards may be attached to electronic devices such as computers or may be formed within a portable computer or other electronic equipment. A keyboard may be provided with a planar housing member such as a top plate. The top plate may have openings through which key caps protrude. Each key cap may be attached to a respective spring mechanism. The spring mechanism for each key may have first and second diving-board structures that flex about respective parallel flex axes. A dome switch may be mounted under each spring mechanism. The dome switch is compressed when the key cap is pressed and the first diving-board structure moves towards the dome switch. The top plate may have edge portions surrounding each key opening that form upstop structures that prevent the key caps and spring mechanisms from tilting when the dome switch is compressed.