If you are coming from a highly technical background, and you want to develop your own document similarity checker like this, the following lines may disappoint you a bit. As I am going to talk for people who are looking for free (and budget-friendly) software which can check similarity in two or more documents side-by-side and help them reduce plagiarism.
If you don’t want to read the full article and looking for the best solution, I will highly recommend you to check these tools I have mentioned in the other post.
Free Software for Document Similarity Checking
If your sole purpose is to find the difference between two text content (text similarity checking) then you don’t need to pay for plagiarism checkers.
There is a tool named diffNow which you can use without paying anything as it runs on advertising income. It works totally fine until you don’t need to detect similarity along with synonym detection and other advanced features.
The diff is actually a command line utility which you can run on your MacOS, Linux and Windows easily. Here is how to do it.
Diff command can be used by entering diff <file1 name> <file2 name> on your terminal. It will show you all the differences in two files character by character. This utility is available by default on Linux and Mac OS. You can manually install it on your windows system or use online with Diff now and other tools.
Note that this type of comparison is good only when you are looking for exact words.
There are other plagiarism detection tools which are free to use online but they either are not effective or save and sell your data to other vendors. (which can lead you to self-plagiarism).
Better Software for Document Similarity and Plagiarism Checking
As plagiarism is not just copying and pasting the text from one content to another, Diff and other similar tools are not much effective. Here are some good tools which are used by popular universities, students, writers and professionals. You can read about them in detail here.
MOSS is heavily used by the professionals and scientists all across the world to detect similarity in different pieces of codes. It is under development since its inception in 1994. It was developed as an open-source and free plagiarism detection software by the students of Stanford University.
How much it costs: $0
Plagiarism Checker X is a multilingual plagiarism checker used in 60+ countries and people from all the domains, including Academia, Literature and Corporate. The biggest sale-point of the software is the security of your content. From their side, there is no chance to leak your private content as you don’t need to upload your data to get checked. Further, it comes will great features like coloured reports, side by side comparison and bulk upload which you can utilize.
How much it costs: Free or $39 or $147 for the lifetime
Grammarly is a popular Grammar editing and writing assistant. However, in the premium plan, it can also detect plagiarism and similarity in different documents. It supports bulk uploading and does way more than simple plagiarism checking. It is a very useful tool which you must check if you haven’t yet already. It’s available for free to start with.
How much it costs: Free or $11 per month to $29 per month.
More Tools Which are Used for Comparing Two Documents
The above-mentioned tools are not the only software you can use. I am a big fan of ProWritingAid, which is another Grammar editing software and spelling checker. It also provides budget-friendly plagiarism checker which is used by thousands worldwide.
Further, Turnitin, Copyscape and other tools are also popular. I didn’t include Turnitin and Copyscape primarily as both of them are very costly in contrast to the features provided by them. Turnitin has a huge advantage of the big database of students’ work they have collected over a period of time. This is the reason that many universities use it as a standard tool. Note that Turnitin is not available for personal use and only Organizations and Institutions can apply for their APIs.
Please help me to make this article better by pointing out grammatical mistakes and sharing better resources.