Best Online Plagiarism Checkers

Most people don’t think twice about plagiarism checkers until they really need one. Maybe it’s a last-minute essay, an article you swear you wrote from scratch, or a piece written by a copywriter that suspiciously echoes someone else’s words. We are drowning in copy-paste shortcuts, and sometimes, it’s smart to double-check your or someone’s work before you hit “Publish” or “Submit.”

Plagiarism tools help you catch accidental overlaps and keep your writing genuinely yours. But they’re not all the same. Some are free but pretty basic, others cost money but go deeper. Knowing which one to go for makes all the difference.

So, whether you’re a student staring down a final draft, an author making sure your piece is unique, or just someone who doesn’t want a surprise plagiarism flag, here’s a quick look at the best paid and free checkers out there.

Best Paid Plagiarism Checkers

Scribbr

Best for: University students, thesis writers, and anyone who needs serious peace of mind before handing in academic work.

Scribbr is widely trusted by students for one big reason: it catches plagiarism that most other tools miss, especially when a text has been paraphrased or edited to look original. Powered by Turnitin’s gold-standard database, it scans millions of journal articles, dissertations, and student papers. In side-by-side tests, it’s often found nearly twice as much plagiarism as cheaper or free checkers.

One thing that sets Scribbr apart is its Self-Plagiarism Checker, which lets you compare your paper to your own past work. If you’re expanding on an old assignment or combining research, this is a lifesaver for avoiding accidental self-plagiarism.

The results come back in a clean, color-coded report that highlights matches by source, so it’s easy to see where you need to add or fix citations. Scribbr’s free Citation Generator also makes it simple to format sources properly if you missed one.

Unlike subscription tools, Scribbr charges per check, from about $20 to $40 depending on word count. There’s no word limit, so you can scan a full thesis in one go. There’s also a limited free preview that flags possible problems, but to see the full details, you’ll need to pay.

Privacy is another plus: Scribbr doesn’t store or sell your work, and files are deleted automatically after 30 days (or sooner if you do it yourself). If something’s off, there’s live support in multiple languages and a straightforward money-back guarantee.

Pros:

• Outperforms other tools at spotting hidden or paraphrased plagiarism.
• Lets you check your own past papers with Self-Plagiarism Checker.
• Clear, downloadable, color-coded reports.
• Includes a free Citation Generator to fix issues fast.
• Doesn’t store or share your documents.
• Good support and refund policy if you’re not satisfied.

Cons:

• Pay-per-check pricing adds up if you run lots of scans.
• No option to edit directly in the report.
• You can’t recheck the same document for free.

If you’re losing sleep over your final paper, Scribbr is about as reliable as it gets. It’s not the cheapest, but for big academic projects, that extra thoroughness is worth it.

PlagAware

Best for: Teachers, schools, and writers who want a straightforward online checker for web sources.

PlagAware sits nicely between free tools and heavyweights like Scribbr. It catches more plagiarism than most budget options, though it’s still not on Scribbr’s level when it comes to academic or heavily edited text. In practice, it works well for basic student papers, simple reports, or online content that needs a quick originality check.

One thing people appreciate is that PlagAware’s online report is clear and color-coded: each source match gets its color, and you get a neat similarity score for every flagged section. The dashboard keeps a tidy history of your past scans, too, which is handy if you check a lot of drafts over time. Just be warned: if you download the PDF version of the report, it’s not nearly as clear. It lumps all sources into the same color, which can be confusing.

Price-wise, you get a one-time free trial (10 pages), but you’ll need to sign up for an account to see your results. After that, you buy credits — about $15 for 100 pages — and pay as you go. There’s no subscription lock-in, but also no unlimited scans.

On the privacy side, PlagAware doesn’t store or sell your work; you can delete documents from your dashboard anytime. There’s no live chat if you run into trouble, but they do have a contact form and phone support if you need a human.

Pros:

• Finds more plagiarism than most mid-tier tools.
• Clear online dashboard with color-coded matches.
• Keeps a running history of your scans.
• Doesn’t keep or sell your files.

Cons:

• Struggles with edited or academic text.
• Downloaded PDF reports are harder to read.
• No live support; just email or phone.
• Only the first 10 pages are free.

If you’re looking for a pay-as-you-go option that’s solid for checking simple essays or web content and don’t need advanced academic matching, PlagAware can be a good middle ground.

Compilatio

Best for: Teachers, schools, and students in Europe who want to check multiple papers over time.

Compilatio is a familiar name in many European classrooms. It’s designed to help teachers and students tackle plagiarism in everyday assignments. It does a fair job finding copied material from the web and other student submissions, but it can struggle when a source text has been heavily rewritten or paraphrased. In testing, it often found the right sources at the start, but its accuracy sometimes dipped deeper into longer documents.

One thing people like about Compilatio is its flexible credit system: instead of a subscription, you can buy credits starting at just a few euros, and they stay valid for a year. You can spread those credits across multiple documents. It’s handy if you’re a teacher checking different students’ work or a student juggling a few big assignments. The tool also lets you compare a new draft against other files you’ve uploaded, which helps catch accidental self-plagiarism.

When it comes to reports, Compilatio’s downloadable version is easy to read and clearly links to the sources it flags. The downside is that it doesn’t actually highlight which specific sentences are plagiarized inside the text itself, so you’ll have to go back and match things up manually, which can be a bit of a hassle if you’re working with big paragraphs.

As for trust, Compilatio doesn’t store or sell your papers to anyone else, and it won’t reuse your files to check other people’s work either. Support is limited to a helpdesk and an online request form.

Pros:

• Flexible credits can be used for multiple checks.
• Helps avoid self-plagiarism by comparing your own uploads.
• Reports link sources clearly.
• Credits stay valid for 12 months.

Cons:

• Doesn’t highlight exact plagiarized phrases in your text.
• Can be tricky to pinpoint and fix issues.
• Performance drops off with heavily edited text.
• No live customer support.

If you’re in Europe and need a budget-friendly tool to run a few checks each term, especially across multiple student papers, Compilatio can get the job done, as long as you’re okay doing a bit more manual fixing afterward.

Grammarly Premium

Best for: Writers, bloggers, marketers, anyone who wants grammar help with a side of basic plagiarism checking.

Most people know Grammarly as a grammar and style tool first, and that’s exactly where it shines. Its plagiarism checker is more of an add-on than a main feature, and it shows. While Grammarly does scan billions of web pages to flag copied text, in real tests, it usually catches less than half of what other dedicated tools find. When it does spot plagiarism, it often only matches part of the copied section instead of the full chunk.

Still, it has a few things going for it: if you’re already paying for Grammarly Premium to fix your grammar, clarity, and tone, you basically get a bonus plagiarism check built in. It also has a handy citation assistant that can help plug missing sources, which is not bad for everyday writing like blog posts, newsletters, or web copy.

Usability is a bit mixed. Finding the plagiarism tool can feel tucked away behind Grammarly’s bigger writing features. And when you do run a check, all matches show up in the same highlight color, which makes sorting through multiple sources tricky. There’s also a word limit: each doc can’t exceed about 100,000 characters (roughly 14,000-25,000 words), so big projects might need to be split up. The total word cap per month is 150,000, whether you’re on the monthly or annual plan.

On the plus side, Grammarly keeps your writing private. They don’t sell or share your files. If you hit a snag, there’s a decent help center and email form, but no live support to get instant help.

Pros:

• Handy bonus if you already use Grammarly for editing.
• Checks your work against billions of online sources.
• Comes with a built-in citation helper.
• Doesn’t share or sell your text.

Cons:

• Finds less plagiarism than specialized tools.
• Highlights all matches in the same color, which can get confusing.
• Big docs might need to be split to fit the word limit.
• No plagiarism checker in the free version — you’ll need Premium.

If you’re mainly worried about clean, polished writing and just want a quick double-check for copied lines, Grammarly Premium does the job. But for a serious academic paper or detailed scan, you’re better off pairing it with a stronger dedicated tool.

Copyleaks

Best for: Businesses, agencies, or tech teams who need to run routine web checks. Not ideal for heavy academic use.

Copyleaks is a flexible cloud-based checker that’s gained some traction with companies and developers, mostly because of its multilingual support and extra features like code plagiarism and AI text detection. But when it comes to straight-up academic plagiarism it doesn’t stack up as well as bigger names. In tests, Copyleaks usually found only about a third of copied text, and the matches it did find were often partial rather than complete.

One practical plus is that the online report keeps your original formatting, so it’s easy to compare your draft and see where flagged content fits in. The report does link each match to its source, but there’s a catch: the downloadable version lumps all sources at the top, so you can’t easily see which bit came from where. Online, you have to click each sentence to view the source, which works but gets tedious fast for long paragraphs.

Copyleaks does try to get fancy by labeling matches as “identical,” “minor changes,” or “paraphrased,” but in practice, its judgment can be hit or miss. The first scan is free for up to 2,500 words, but after that, you’ll need to sign up for a monthly plan. Prices start around $17 a month for small projects or a bit cheaper per month if you pay yearly.

Privacy is one area where Copyleaks is a bit vague — the site promises it “will never steal your work,” but there’s no clear automatic deletion. You’ll have to reach out to customer service to get your files permanently removed. They do have a contact form and a chat option if you run into issues.

Pros:

• Keeps your document formatting intact in the online view.
• Links flagged text to the source clearly in the online report.
• Handles web and code plagiarism, plus AI content checks.

Cons:

• Academic performance is weak. Mostly partial matches.
• Downloadable reports are confusing to cross-check.
• First scan only covers 2,500 words for free.
• Unclear how long your files stay on their servers.

If you’re a business, agency, or dev team looking for an all-rounder to plug into your workflow, Copyleaks is worth considering, especially for web or tech content. However, for students or researchers seeking reliable academic checks, stronger options are available.

Best Free Plagiarism Checkers

DupliChecker

Best for: Casual writers, students, and bloggers who want a quick, free check for short texts.

DupliChecker is one of those simple, old-school tools that’s been around forever, mostly because it’s free and gets the job done for basic checks. You can scan up to 1,000 words at a time at no cost, which is fine for short blog posts or school paragraphs but means you’ll be chopping up anything longer into smaller chunks. They do have paid plans if you want to go up to 25,000 words.

When it comes to catching plagiarism, DupliChecker is decent but not perfect. In tests, it usually flagged a bit over 40% of copied text, which isn’t bad for a freebie, but it struggled to find full matches. If you’ve got a fully plagiarized sentence, it often only highlights part of it. So, it’s better as a quick scan than a final verdict.

On the plus side, DupliChecker’s reports are relatively clear for a basic tool. You get a simple percentage match and see which bits were flagged, but there’s no fancy color-coding for different sources, so sorting out who wrote what can take a bit more digging.

One thing users appreciate is that DupliChecker says it doesn’t store your files. It deletes them after each check to help protect your work. There’s no live support if you get stuck, but there’s a basic contact form if you need to reach out.

Pros:

• 100% free for up to 1,000 words per scan.
• Doesn’t save your uploaded files.
• Supports multiple file formats (Word, PDF, TXT, etc.).
• Reports are clear enough for quick edits.

Cons:

• Detects only partial matches, misses full sections.
• No color coding by source.
• Free plan is limited to short texts; longer checks get clunky.

If you’re a student double-checking a short essay or a blogger tidying up posts, DupliChecker is fine for a fast scan. Just don’t expect miracles. For anything serious or long, you’ll want a stronger tool or be ready to split your text into chunks.

Check-Plagiarism

Good for: Bloggers and students who write a lot of short pieces.

Check-Plagiarism is another no-frills tool. Paste your text, run the scan, and you’ll get color-coded results showing where your phrases match what’s online. The free version has a limit per scan (about 2,000 words) but you can run multiple checks if needed.

What works:

• Decent match accuracy for web content.
• Simple interface, no clutter.
• Free forever for small scans.

What’s not so great: The ads can get annoying, and you won’t get deep database coverage like you would with Turnitin-based tools. But for blog posts or short essays, it’s handy.

Small SEO Tools

Good for: Content creators, SEO writers, small website owners.

Small SEO Tools is an old favorite for bloggers who want to avoid duplicate content penalties. You can paste your text or enter a web page URL to see if it overlaps with anything already indexed. It’s really designed for web writers, not students writing research papers.

Why use it:

• No sign-up is needed.
• Unlimited scans.
• Bundled with other SEO tools like keyword checkers.

What to know: It’s pretty basic — the report just shows matched lines with source links. Also, the ads can be over the top. Still, if you’re doing SEO for a client blog, this is an easy final check.

Plagiarism Detector

Best for: Bloggers and students who need a quick, basic scan for short bits of text.

Check-Plagiarism is another free tool in the same league as DupliChecker. It’s handy for fast checks if you’re working with short assignments or online content. You can upload up to 1,000 words at a time for free, but there’s a catch: the site technically limits guests to 50 “search queries” a month (where one sentence counts as one query). In reality, this cap doesn’t always kick in, but if you want more wiggle room, you’ll need to grab one of their short-term paid plans.

In practice, this checker does a so-so job of finding matches. It picks up an average of about 37% of copied content. Not terrible for a free tool, but definitely not enough for a serious paper. It also tends to scan sentence by sentence, which means it often highlights only parts of a plagiarized section instead of the whole chunk. Scholarly or heavily paraphrased text tends to slip through, too.

One plus is that the online report shows each flagged bit with a small source box, so you can see where it came from without too much digging. Unfortunately, if you download the report, it’s more of a pain: it just dumps all sources in a big list that’s tricky to match back to your text. The tool also uses the same highlight color for every source, which doesn’t help.

Usability could be better. The site is loaded with ads, so it’s easy to get sidetracked by pop-ups or click the wrong button. There’s also a built-in “rewrite” tool, but all it really does is swap out words, and it won’t actually solve plagiarism problems. A simple citation helper is included, too, but it’s pretty basic.

On the privacy side, Check-Plagiarism says they don’t keep or share your files, which is good. There’s no live help if you run into issues, just an FAQ page (which is a bit vague) and a contact form if you want to reach out.

Pros:

• Free scans up to 1,000 words.
• Online report links text to sources clearly.
• Quick and easy for short pieces.

Cons:

• Average detection rate, misses a lot, especially on scholarly material.
• Same color highlights for all sources.
• Downloadable report is awkward to cross-reference.
• Cluttered with ads that get in the way.

If you’re scanning a blog post or small assignment, Check-Plagiarism can catch obvious overlaps. Just don’t expect it to handle serious academic work or to replace a real rewrite or citation.

Quetext

Best for: Writers or students who want a simple plagiarism checker with extra writing tools but don’t need deep academic accuracy.

Quetext has built up a big following, over 2 million users, mostly thanks to its simple interface and decent accuracy for light checks. It scans your text against web pages, academic papers, and past uploads, and also tosses in extras like a citation helper and grammar check. But when you dig deeper, its detection power is pretty average compared to stronger tools.

Usability is where Quetext really loses points. The online report and the downloadable PDF mess up your text’s original formatting. Instead of showing different colors for different sources, Quetext only uses two: red for fully copied chunks and orange for partial matches. This makes it harder to keep track of which source is which, especially for longer work.

On the upside, Quetext’s paid plans are affordable, starting at about $8.80 a month, and the platform says it doesn’t store or reuse your documents, which is a plus for privacy. There’s a help center for FAQs and an email form if you run into problems, but there’s no live chat or instant support.

Pros:

• Simple interface and easy setup.
• Includes a citation tool and basic grammar checker.
• Affordable paid plans for light use.

Cons:

• Often breaks your formatting in reports.
• Only two highlight colors, so it’s hard to sort sources.
• No live support if you get stuck.

If you’re after an easy, budget-friendly tool to scan short web copy, Quetext can help catch obvious overlaps. But if you’re checking a research paper or thesis, you’ll probably want something more precise and easier to read.

PrepostSEO

Best for: Bloggers, students, and small content teams who want an affordable mix of basic plagiarism and SEO tools.

PrepostSEO is a popular pick for people who need a quick all-in-one toolkit; not just plagiarism checking, but also keyword tools, article rewriters, and other SEO helpers. Its plagiarism checker does an okay job for simple web content, but don’t count on it for deep academic scans.

In testing, PrepostSEO could sometimes find full copied sections and usually matched them to the right source. But once text had been paraphrased or lightly edited, it often missed big chunks, especially when the source was scholarly or more specialized. So, it’s best used for catching obvious copy-paste, not subtle paraphrasing.

One thing that makes PrepostSEO handy is its built-in rewriting and paraphrasing tools. In theory, they can help you fix flagged sections, but users often find they’re a bit clunky and don’t always fix plagiarism properly.

The online report does link flagged text directly to its source, which helps, but there’s no color coding for different sources. Everything’s highlighted the same way, which can be a pain in longer documents. The PDF version is even less helpful: it doesn’t clearly mark which text came from where, so you’ll need to double-check manually.

If you want more than the free version, a basic plan starts at $10 a month and covers about 5,000 sentences. Not bad for casual bloggers or students. On privacy, PrepostSEO says it doesn’t keep or share your files, which is reassuring. There’s no live chat for quick help, just a contact form if you run into trouble.

Pros:

• Budget-friendly, good for quick web checks.
• Includes built-in rewriting and paraphrasing tools.
• Doesn’t store or sell your documents.

Cons:

• Struggles with edited or academic text.
• The PDF report is hard to read; no source breakdown.
• All sources use the same highlight color.
• Rewriting tool can be hit or miss.

If you need a free or cheap option to catch obvious copy-paste content and want a few extra SEO tools thrown in, PrepostSEO is worth a look, just don’t rely on it alone for serious research papers.

Summary

No plagiarism checker is perfect, but choosing the right one can make the difference between a quick peace-of-mind scan and catching mistakes that could cost you grades, credibility, or search rankings.

If you’re a student turning in serious academic work, it’s usually worth paying for a tool like Scribbr, which digs deeper and handles tricky cases like paraphrased or heavily edited text. For teachers or small institutions, PlagAware and Compilatio can be practical mid-range options that cover multiple student papers at once.

If you’re a writer, freelancer, or business that wants an everyday safety net, Grammarly Premium can be a handy extra layer on top of your grammar checks, but it shouldn’t be your only line of defense for bigger jobs. And for casual bloggers or students who just want a fast, no-cost check, free tools like DupliChecker, Check-Plagiarism, Quetext, or PrepostSEO can catch the most obvious overlaps, as long as you keep their limits in mind.

No matter which tool you choose, a plagiarism checker should be your safety net, not your only plan. Good research habits, proper citations, and careful editing still matter more than any scan. Run your text through more than one tool if you can, double-check sources manually, and when in doubt, cite it properly.

Original work builds trust, and in the long run, it’s the easiest way to keep your writing (and reputation) clean.