The Constitution of India is federal in character because:

The Head of the State (the President) is elected by an electoral college consisting of the elected members of both the Houses of Parliament and the elected members of the Legislative Assemblies of the States

The Governors of States are appointed by the President and they hold office during the pleasure of the President

The amendment of the Constitution can be made only by following the procedure laid down in the Constitution and in some cases the amendment requires ratification by Legislatures of the States