1, pay attention to whether the free comparison database of the paper duplicate checking website is the same as the paid one. Generally, it will be indicated on the website that if it is smaller than the charge, the result will not be very reliable;
2, free papers to check the safety of the website itself, although free is more fragrant, but security can not be ignored. Check the history and registration information of the website to see if there are any formal procedures. If not, it is not recommended.
3. Free ways to check websites with duplicate free papers. If the registration is completely free and there is no word limit, it is best not to use it. It is terrible that there is no profit in duplicate checking websites, especially those websites that don't even need to register and check duplicates directly for free.
4. A regular free paper duplicate checking website will not be completely unlimited and free. Generally, you need to pay attention to or share, and then give the corresponding free duplicate words. This is more reliable, users who directly recharge use the same system, and the comparison data is the same.