The IELTS tests four skills including listening, reading, writing, and speaking.
The TOEFL measures the ability of international students to use and understand English at the university level.
The TestDaF is a German language proficiency test recognized by the German government. The TestDaF is most commonly taken by people who want to study at the university level in Germany.
The International English Language Testing System lists language assessments in more than 90 languages.