Editing and proofreading written passages is difficult and time-consuming, and to do it well requires a high level of language proficiency. Most people are not willing to do it for free. There are probably other websites where you can post your writing and wait to see if anybody is willing to correct it (the same as on Italki), but there certainly aren't any websites that automatically offer to correct written passages for free.

YES THERE IS

There are very few free things in life. Professional editors correct books before the books are published. Part of the book's sales pays the editor's salary. Teachers correct student assignments. For government-run schools, taxes pay the teacher's salary. A few italki members correct short texts in the notebook section. Sometimes they add errors because they are not teachers or editors. Long texts are usually ignored because of the amount of work. If you have texts to correct and you want high-quality correction, you will probably need to pay money. If you live near a university, you may find advanced English students who will accept a lower payment than an editor or a teacher.

There is limited help available with the free version at grammarly.com.