Many writers use Grammarly to help with proofreading, fixing grammatical errors, sentence structure, readability, word count, and so forth. While the free version is a great tool to have for writing grammatically correct content, you’ll also want to include a plagiarism checker in your final stages of the writing process. Quetext provides the most advanced plagiarism-checking algorithm on the internet at no to low cost. You can try it out for free, and if you need more, the most you’ll ever pay is $10/month.