Teachers will be able to get an instant analysis of how their pupils fared in each A-level and GCSE question when results are published later this month.
In another example of the computer-driven evolution of England's exams system, the Edexcel board is making the service available for subjects sent for marking by examiners electronically this year.
Around a quarter of the papers taken by Welsh pupils are with English boards such as Edexcel. Meanwhile, the Welsh Joint Education Committee, Wales's exam board, is hoping to start work next year on using information technology to process exams and communicate with schools, following the announcement in June of extra cash for modernising its systems.
The Edexcel system will allow teachers to log on to a secure website and see the average mark for their school's pupils in each question of a particular paper. The service should be available on the day the results come out - next Thursday for A-levels.
Teachers can then compare this against the national average for all pupils on that question. They can also contrast the results between different categories of schools, for example selective secondaries or comprehensives.
The website will give schools an early preview of chief examiners' reports in particular subjects, offering them the chance to compare their pupils' results on a question with expert views on how students across the country answered it.
The service is being made available by Edexcel only for the 44 papers, in subjects ranging from A-level biology to GCSE French and science, which were marked electronically this year.
The board believes the service will help schools make more informed judgments about which areas of knowledge are being taught well.