Listing and linking to these resources does not indicate GCC's endorsement of said resources (Editor's Note: I've actually seriously considered deleting this section altogether due to the controversy surrounding the use of these resources, but...)
- Please keep in mind that the efficacy of each platform is not consistent. No one platform is 100% foolproof.
- Sources are listed in alphabetical order
- Many of these are free but simply require you to set up an account. But yes - some only allow a free trial period.