Open Admin for Schools is a School Administration Program. It is a freely available, open source software package and is licensed under the GNU General Public License.
It is entirely web based and can run from a centrally located division wide server or a single computer in a school. It is designed to support an entire division on one or more central computers but can also work just fine for a single school. Currently several school divisions use this approach and have 15+ schools on a single central server. This is because it is designed to be lightweight both in server resource requirements and in communication bandwidth.