Capita Education Services has assured the Office of Fair Trading that it will give rivals the information they need to make their products compatible with Capita's Sims software, which is already used by 22,000 schools for attendance records and target setting.
Last year, the OFT launched an investigation after complaints from London-based Bromcom Computers Plc. Ali Guryel, Bromcom's managing director, said the agreement was good news for schools, which would benefit from a wider choice of products and prices.
He said: "We believe in open systems and co-operation. Without that, you cannot give the best services and systems to users."
Capita said it had not broken competition laws, and that the solution agreed for other firms to interface with its software is the same one it proposed 18 months ago.
Phil Neal, Capita's strategic and product director, said: "We will work to ensure that Capita and its partners continue to provide the education sector with relevant and high quality software and services."
The company has, however, agreed to provide a manual for its rivals.
An OFT spokesman said it was correct to say there had been no breach of competition law. But if Capita fails to uphold the assurances it has made, the case could be reopened.