Effective detection of plagiarism requires primarily the current and complete database of scientific texts in a given field. That's why it's hard to talk about the program, but rather about the (web) service. There are several such services, but most of them are paid (see, for example, https://www.crossref.org/fees/#similarity-check-fees).

Gathering full texts of scientific articles (and not just searching the resources of the Internet) must generate costs, so effective detection of plagiarisms can not be costless too.

Most of the free platforms will not check against scholar sources but only against Internet resources, which is obviously insufficient.

Have you tried the obvious ones yet?

http://lmgtfy.com/?q=free+plagiarism+checker

Dear Dr. Shridhar Mathad,

Attached herewith the list of Top or Best Plagiarism software or checker or detectors having free of cost access. Also I have added list of Paid access.

01. Dupli Checker:

This is one of the most effective free plagiarism detection tools on the Internet. While it doesn’t have a fancy interface, it certainly gets the job done well.

Pros

• Free Of Charge You don’t have to pay anything. Whether you are a one-time user or plan to make the most of this free plagiarism detection tool on a daily basis, you are not required to pay for subscription.
• Ease Of Use You are presented with a very basic, functional layout that does not require for any previous experience with plagiarism detection tools.
• 2 Ways To Check For Plagiarism Duplichecker enables you to either copy and paste your text in the field and then check it for plagiarisms, or upload a Docx or Text file from your computer.
• 50 Plagiarism Scans Per Day For Registered Users If you sign up for free, Duplichecker allows you to do 50 plagiarism checks in a single day.

Cons

• 1 Search Per Day For Unregistered Users If you choose not to indulge in a free sign-up then you are limited to only 1 plagiarism check per day.

Plans And Pricing

• No paid version is available.

02. Copyleaks:

This cloud-based authentication platform enables you to track how eLearning content is being used all around the Internet.

Pros

• For Education And Business Different sections on the platform for educational and business purposes. The business section addresses to publishers and SEO agencies, while the education section to schools, students and universities.
• Multiple File Formats And Languages Copyleaks is able to scan content in various file formats and all Unicode languages.
• Variety Of Tools Copyleaks allows you to use the API tool to search for plagiarized eLearning content all over the Internet. It also offers a mobile app along with an MS Office add-on, which you can use to check for plagiarisms as you are writing a document on MS Word.

Cons

• You Can Use It Only After You Sign Up Unfortunately, you need to create an account for free first, in order to search for plagiarized eLearning content.
• Free Page Restriction Only the first 10 pages are for free.

Plans And Pricing

• For Businesses If you sign up for free you are allowed to check 2,500 words per month. There are flexible subscription plans starting from $9,99 per month to check up to 25,000 words without day limit. You may also choose to give a prepaid amount of money once that corresponds to specific number of words to be checked monthly.
• For Education The Free package works the same as for businesses. Starting from $10,99 you can check for up to 25,000 words. The prepaid option for business, is also available here.

03. PaperRater:

A multi-purpose free plagiarism detection tool that is used in over 140 countries.

Pros

• 3 Tools In 1: Proofreader & Grammar Check, Vocabulary Builder, Plagiarism Checker If you need to check your text for grammar mistakes, have it proofread with suggestions for different wording, or have it checked for plagiarism, this is the tool.
• Developed By Industry Experts Developed by a team of computational linguists and subject matter experts.
• Fast Results PaperRater boasts accurate results in seconds.

Cons

• No Ability To Save Reports If you are looking to store result report, then you are out of luck here.

Plans And Pricing

• Basic Free of charge, submissions of up to 5 pages, grammar and spelling check, writing suggestions tool and automated scoring.
• Premium $7,95 per month or $95,40 per year. All above features included plus proofreader with simultaneous plagiarism check, no ads, file uploading ability and faster processing times.

04. Plagiarisma:

Basic and easy-to-use, multi-purpose plagiarism detection tool that is used by students, teachers, writers, as well as various members of the literary industry.

Pros

• 190+ Languages Supported There is virtually no language excluded from the list.
• Plagiarism Check By URL, Online Or File Upload Copy and Paste or Τype your text in the appropriate field, provide a URL, or upload a file from your computer. Supported file types include: TXT, HTML, RTF, DOC, DOCX, XLS, XLSX, PDF, ODT, EPUB, FB2, PDB.
• Firefox And Chrome Extensions Have your text quickly checked by downloading the add-ons.

Cons

• Limited Plagiarism Checks Per Day If you are looking for a tool for extensive use then look somewhere else. The free version has a limited number of plagiarism checks.

Plans And Pricing

• Variety Of Plans Free version of Plagiarisma offers all the aforementioned benefits. If registered, you can upgrade to Premium Members hip. Pricing plans start from $5 for one day for up to 100 searches. For unlimited searches, there is a $25 or $30 subscription for 3 or 6 months, respectively. For up to 25 users, there is a fixed monthly subscription of $25 for unlimited number of searches.

05. Plagiarism Checker:

User-friendly, entirely free plagiarism detection tool to check whether content is plagiarized.

Pros

• Detailed Guidelines One of the easiest to use free plagiarism detection tools due to its step-by-step approach on how to use it.
• Check If Others Have Plagiarized Your Online Content Click on the “For authors” option to check whether they have plagiarized your content and posted it on the Internet. You may also get a notification by email.
• Entirely Online No downloads required.

Cons

• Supports Only Google Or Yahoo Browsers If you are using none of those 2 browsers then you might want to look elsewhere

Plans And Pricing

• Free of charge.

06. Plagium:

Basic but fully functional free plagiarism detection tool with different levels of search.

Pros

• Easy to use You basically copy-paste text. It features 2 types of searches, quick search and deep search.
• Free For Up To 5,000 Characters Each Time For up to 5,000 characters per search you don't have to pay any fee.

Cons

• Limited Free Features Only if you sign up you can upload your file, have it checked, and receive a word usage report on it.

Plans And Pricing

• Quick Search And Deep Search Offers If you are a frequent user of the platform, Plagium urges you to pay for a subscription. For $9,99 per month you can do 287 Quick Searches and 143 Deep Searches. For $24,99 per month you can do 699 Quick Searches and 349 Deep Searches. The last option is a $99,99 per month subscription which offers 2,949 Quick Searches and 1,474 Deep Searches.

07. PlagScan:

Plagiarism detection tool for both individuals and businesses that checks texts against online content, scientific journals and the user’s documents as well.

Pros

• Fully Online No download required.
• 3 Ways To Do Plagiarism Checks You can select from: a) directly pasting you text into the appropriate field, b) importing the file from the web by entering its URL at the indicated area, or uploading it from a cloud storage area such as Dropbox, Google Drive, or OneDrive, c) uploading a file from your desktop.
• No Subscriptions For Private Users The user pays on-demand according to their respective needs.
• Integration Features Businesses can integrate Plagscan into several Content and Learning Management Systems (CMS/LMS).

Cons

• Relatively Complicated Interface As opposed to competitive platforms the interface seems quite advanced.

Plans And Pricing

• Private Users Starts from $5,99 per month with online storage time for up to 6 months.
• Organizations Accounts for schools, universities or companies start from $19,99 per month with unlimited online storage time along with a variety of administration and cloud features.

08. PlagTracker: Fast free plagiarism detection tool that searches both websites and academic databases by copying and pasting text, or file uploading.

Pros

• Addressing To Different User Groups Students, teachers, publishers and site owners can take advantage of Plagtracker.
• Detailed Reports The user gets informed as to what parts need to be cited and a list of sources to be used.
• 6 Languages Supported Check your eLearning content in English, French, Spanish, German, Romanian and Italian.

Cons

• No File Upload In Free Version You have to purchase a premium package to have your file uploaded and checked.

Plans And Pricing

• One Premium Offer For $7,49 per month you can upload and check larger files with faster processing times, grammar checks and unlimited checking volume for multiple documents.

09. Quetext: Basic layout and functional interface that checks against the Internet, as well as various databases.

Pros

• No Subscriptions Quetext is entirely free.
• Unlimited Usage No account, registration or downloads needed.

Cons

• No File Uploading Users can only copy and paste text in the designated area.

Plans And Pricing

• Free of charge. No premium memberships. No subscriptions available.

10. Viper: A 3-step free plagiarism detection tool with user-friendly interface.

Pros

• 100% Free All features are available to everyone on the Internet.
• Extensive Plagiarism Check Range Your document will be checked against more than 10 billion online resources including journals, books and websites.

Cons

• Limited Target Group Mostly targeted to academic students as it is widely used for evaluating student papers.

Plans And Pricing

• No subscriptions available. Entirely free platform.

11. Grammarly’s:

GRammarly's plagiarism checker can detect plagiarism from billions of web pages as well as from ProQuest’s academic databases. Our free plagiarism check will tell you whether or not your text contains duplicate content. Our Premium plagiarism check highlights passages that require citations and gives you the resources you need to properly credit your sources.

Pros

• Whether you’re a student writing an essay, a teacher grading papers, or a writer working on original content for the web, a plagiarism scan will not only save you time, but also help you avoid writing mistakes.
• Grammarly is trusted by over 600 universities and millions of bloggers, writers and creative people.
• Detects the slightest chance of plagiarized content and displays percentage report.
• Efficient grammar and punctuation checker (you sure can have different tools for this, but having everything in one place is a bonus).
• Free online plagiarism checker with percentage.
• Proofreader at its best along with free PDF report of all errors (including detected plagiarism) that can be exported.
• The ability to scan document based on document style and type makes it even more efficient than it’s competitor plagiarism checkers.
• Emails you your weekly performance report (how many words you wrote, improvement in writing style etc) which is a good boost if you’re using to improve your English on the side.

Cons

• I’ve been using Grammarly for quite a couple of years now and Grammarly plagiarism checker has no cons to be honest and it shows why it is the most used plagiarism checker by writers, bloggers and academic professionals.

12. Small Seo Tools:

SmallSEOTools is unique in its own way. It is a platform where one can get several tools with highly lavish features.

Besides providing a plagiarism detection tool, it also offers a host of other useful SEO tools such the Article Rewriter, Keyword Position, Online Ping Website Tool, Backlink Checker, Backlink Maker, Link Tracker, Google PageRank Checker, Domain authority checker, Word Count Checker, Spell Checker tool, and many more.

Although its plagiarism checker is quite a basic type, people love it as it is totally free of cost.

Once you copy-text then paste in the given space and click the ‘Check for Plagiarism’ button, it would check the text in seconds. You can see the copied text in red.

If you’re looking for a free plagiarism checker then SmallSEOTools’s Plagiarism checker is one of the best sites to check plagiarism.

Pros

• SmallSEOTools is a simple and effective free online plagiarism checker for students.
• Offers a variety of other tools which can be helpful if you’re looking to check plagiarism for web content.
• The ability to upload documents from cloud (google drive and dropbox) makes it a winner in our list of duplicate content checkers.

Cons

• The free version is not as effective as premium versions of Grammarly or Whitesmoke’s.

13. Edubirdie:

EduBirdie custom essay writing service is well-known for providing dependable and expert writing assistance for students.

Purchase your next assignment online, provide your basic requirements and then leave the rest to our team.

Our professional writers have in-depth knowledge of various kinds of subjects including Literature, Sociology, Psychology, English, Business, etc. Moreover, we have a team of native English speaking writers, who are passionate about writing and doing academic research.

More importantly, all works are 100% unique and non-plagiarized. If you’re not happy with the quality of the essay, you’ll get your money back.

You can always count on EduBirdie’s friendly customer support for any issues you might have. Our support team is here for you 24/7.

Every paper is thoroughly inspected and double checked for originality prior to delivery. This way, you are sure to get a high-quality essay tailored to your specific needs.

Pros

• High-quality service
• On-time delivery
• Professional writers
• Non-plagiarized content
• Responsive customer support
• Affordable Prices

14. Dustball:

Dustball is a decent & free paraphrasing checker that you can use on the go. It has a premium plan that Dustball claims to be 3x more accurate. I haven’t tried the premium ones but I think they’re worth a mention.

15. DMCA:

If you run a website or blog then you can understand how hard it is to find content scrappers that steal your content and publish it elsewhere. DMCA comes to the rescue from this type of plagiarism.

With over 862K sites trusting them, DMCA is one of the most reputed and competent tool for copyright infringement. It helps you protect your intellectual content from piracy and thus save you from duplicate content penalty from search engines.

If found guilty, you can file a DMCA content take-down notice and the culprit site/source will be taken down based on the stipulation of the Digital Millennium Copyright Act. This support definitely makes it one of the best plagiarism checker tools if you want to protect your content online.

Pros

• Protects website, images, videos, graphics and text from theft.
• Since it is the most respected authority on copyright infringement, the badges it offers let’s your visitors know that you own the rights to the content and it cannot be reproduced elsewhere.
• Allows you to add watermark to images to discourage hotlinking, image theft (you can watermark millions of images in seconds).

Cons

• The free version allows only 2 scans and requires you to opt for the paid scan.

16. Unicheck:

Unicheck is a good text similarity checker. It boasts about having over 40 billion web pages & educational database to check your content originality and displays all in a beautiful color coded format.

You get to use bulk data processing and isolated user accounts to carry out your work fast without worrying about security breaches.

Unicheck plagiarism checker comes with API access, Google docs add-on, G Suite add-on and Office 365 add-ons to enable easier access. Not to mention the personal dashboard to check in a single browser tab.

17. WebConf's similar page checker:

WebConf’s tool is another similar page checker that’s worth a mention. Unlike other duplicate content detectors. This tool checks and tells the percentage of similarity between two web pages.

List of top best paid plagiarism checker tools:

01. Turnitin:

Turnitin celebrates the writing process. They partner with educators to share smart, creative practices for writing instruction. Explore our blog, teaching tools, guides, white papers, and more.

02. Whitesmoke:

Whitesmoke is one of the top plagiarism checking software that is very robust and accurate. Besides being a grammar checker and proofreader, Whitesmoke’s anti-plagiarism software is trusted by many.

Whitesmoke scans billions of online web pages and resources to check for unoriginal content or copied content in your document and displays the same.

Whitesmoke online plagiarism checker isn’t as famous and efficient as Grammarly’s but makes a great alternative if you want to try out. With browser, MS Word and Outlook integrations it takes your content analysis to the next level.

Pros

• Scans and matches your essay with billions of web pages to detect similarity in your essay.
• It is cross platform supported and also available online so its easy to use.
• Best plagiarism checker for research papers.

Cons

• Doesn’t have as large a database as Grammarly
• There are not many cons of Whitesmoke so you can choose it safely.

03. ProWritingAid:

ProWritingAid’s online plagiarism checker tool is one of the best in the market. It helps to check for copied content in manuscripts, novels, or literary works. ProWritingAid is the best website for plagiarism check for authors/creative writers.

Besides being a trusted duplicate content checker, ProWritingAid shows up as your writing coach. It detects grammar errors, style issues, and over 20 different mistakes that authors and editors are likely to make. Check out my detailed ProWritingAid review to know why it is one of the perfect Whitesmoke alternatives out there.

Pros:

• Checks for plagiarism directly from the MS Word via the add-in.
• Works fine with Scrivener and is the best plagiarism checker for Google docs.
• It effeciently detects even 10% plagiarism in your manuscript.

Cons:

• Lowest plan starts at $10 for 10 checks or $60 for unlimited checks.

I hope I have answered your question.

With Best Wishes,

Samir G. Pandya