There is an ever growing collection of resources on the TES site. Registration is free and many high quality resources are available. Start at the Secondary Maths page for resources for students age 11-18 and the Primary pages for younger children.
Note the very useful collections page on the Secondary page which organises resources into groups. There are several new Topic Specials where members of the TES Maths panel, of which I am very pleased to be a member have picked their favourite TES resources for teaching a variety of topics. Note the GCSE Problem Solving Questions of the Day – an outstanding resource from the White Rose Maths Hub.
You can search the resources, for example you could search on KS4 (UK ages 14-16) Algebra.; you will see that some resources have been recommended by the TES Maths Panel. There are many high quality (free) resources. Search on revision resources for example. Note the numerous 5 star reviews given for many of these resources. You can filter the search by age using the criteria on the left of the page or the tabs at the top; see revision resources for 14-16 for example.
Craig Barton regularly pick his favourite TES resources.