I want to apply for skilled migration, but it has been free for two and a half years. How to provide this work certificate when applying for immigration?

The current skilled migration program in Australia generally requires you to have at least one year of stable work experience in the last two years, but you don't need to provide all the work experience so far. If you have seven years of service, I don't think this should be a problem.

Generally speaking, the organization for professional evaluation in IT industry should be the Computer and IT Talents Association of Australia. For details, please refer to the professional evaluation form issued by the Australian Immigration Bureau.