If you're looking for a Writable alternative, Brisk is a good option. Brisk is a Chrome extension that works with Google Docs, Slides and YouTube to let teachers automate some work and offer students more detailed feedback with AI tools. It has a range of features, including an AI feedback generator, presentation creator and quiz maker. It's free for teachers, so it's a cheap alternative that can help you get more out of your teaching.
Another good option is Studyable, an AI-based learning platform that offers tools to help with homework and grade essays. It's got features like instant essay feedback, math problem help with homework and flashcard creation from your notes or course syllabus. It's got a free tier, so it's adaptable to different academic situations.
If you're looking for something more focused on essay grading, EssayGrader is worth a look. It uses AI to grade essays and has tools to help teachers find grammar, punctuation and style problems in essays. It offers several pricing tiers, including a free option, so it's a good option for different levels of education. EssayGrader also can handle multilingual text and offers detailed reports on student performance.