Someone copying your blog posts is annoying, but the real cost is in search: when the same text exists on several sites, Google has to pick one version to rank, and it does not always pick yours. The reverse problem matters too: a guest post or freelance article that was lifted from elsewhere can hurt your site. A duplicate content checker catches both. This guide covers the nine tools worth using in 2026, what each is for, and what they cost.
Updated October 2026: Article Checker and the old Google Webmaster Tools method were removed; Siteliner, Quetext, Copyleaks, and Small SEO Tools were added, and every tool was checked.
Duplicate Content Checkers Compared
| Tool | Best For | Input | Price |
|---|---|---|---|
| Google Search | Quick check of one phrase | Phrase in quotes | Free |
| Copyscape | Finding who copied your page | URL or text | Free URL check; Premium 3 cents per search |
| Grammarly | Checking drafts while writing | Text | With Grammarly Pro |
| DupliChecker | Free text checks | Text or file | Free, 1,000 words per search |
| Plagiarisma | Non-English content | Text, URL, or file | Free with limits |
| Siteliner | Duplicate pages on your own site | Domain | Free up to 250 pages |
| Quetext | Detailed similarity reports | Text or file | From $8.80 per month |
| Copyleaks | Plagiarism plus AI detection | Text, file, or URL | From $8.99 per month |
| Google Alerts | Catching new copies automatically | Phrase | Free |
1. Google Search
The fastest check needs no tool at all. Copy a distinctive sentence from your post, put it in double quotes, and search. Google returns every indexed page containing that exact phrase. If a site other than yours appears, open it and see how much was copied. This works for spot checks but is slow for a whole post and misses pages Google has not indexed.
Pricing: Free.
2. Copyscape
Copyscape is still the standard for finding copies of a published page. Enter your URL and it lists pages that match, with the amount of overlapping text. The free check is limited to a few searches a day per site; Copyscape Premium costs 3 cents per search (plus 1 cent per 100 words beyond 200) and lets you paste text, check in bulk, and run Copysentry, which monitors your site and emails you when a copy appears.
Pricing: Free URL searches with daily limits. Premium from 3 cents per search; Copysentry monitoring from $4.95 per month.
3. Grammarly
Grammarly\’s plagiarism checker compares your draft against billions of web pages and academic databases and flags matching passages with their sources, inside the same editor that checks grammar and tone. It is the right tool for checking a guest post or freelance article before you publish, since you are already editing it there. The checker is part of Grammarly Pro. See our grammar checker tools post for how Pro compares.
Pricing: Included with Grammarly Pro ($12 per month on annual billing).
4. DupliChecker
DupliChecker is the most generous free option: paste up to 1,000 words or upload a document and it reports the percentage of unique and plagiarized text with links to the matching sources. Registering lifts the daily search limit. It is ad-supported, so expect a busy page, but the results are reliable for short posts.
Pricing: Free, 1,000 words per search. Premium removes ads and raises limits.
5. Plagiarisma
Plagiarisma checks text, a URL, or an uploaded file and highlights matched sentences, with support for 190+ languages, which makes it the best free choice for content that is not in English. It has desktop apps for Windows and Android as well as the web version.
Pricing: Free with daily limits. Premium removes limits.
6. Siteliner
Siteliner, made by the Copyscape team, solves a different problem: duplicate content inside your own site. Enter your domain and it crawls up to 250 pages for free, showing which pages share large blocks of text (category pages, tag archives, near-identical posts), plus broken links and page power. Internal duplication is a common reason thin or repeated pages do not rank, and this is the quickest way to see it.
Pricing: Free up to 250 pages per month. Premium 1 cent per page.
7. Quetext
Quetext\’s DeepSearch gives one of the clearest reports: a color-coded view of your text with exact, near-exact, and paraphrased matches, each linked to its source, and a citation generator for anything you need to credit. It also includes an AI content detector. The free plan covers a short trial; paid plans start at $8.80 per month.
Pricing: Free trial. Essential from $8.80 per month.
8. Copyleaks
Copyleaks is used by universities and publishers for plagiarism and AI-generated text detection together. It checks files, text, and URLs, compares across languages, and produces a shareable report. For a blog it is more than most people need, but if you accept paid guest posts or buy articles from writers, its AI detector is the most accurate of the tools here.
Pricing: Free credits to start. Plans from $8.99 per month.
9. Small SEO Tools Plagiarism Checker
Small SEO Tools checks up to 1,000 words per search for free, sentence by sentence, and shows the matching source for each flagged sentence. It is a good second opinion when another free checker gives an unexpected result.
Pricing: Free, 1,000 words per check.
10. Google Alerts
The tools above find copies that already exist. Google Alerts catches new ones: create an alert for a unique phrase from each post (in quotes), or for your blog name, and Google emails you when that phrase appears on a newly indexed page. It costs nothing and takes a minute per post.
Pricing: Free.
What To Do When Someone Copies Your Content
- Check whether the copy links back to you. A scraper with a link is annoying but mostly harmless; one without a link is worth acting on.
- Email the site owner and ask for removal. Many comply.
- If they do not, file a DMCA request with their host, and a removal request with Google so the copy drops out of search. Our guide to reporting copied content to Google walks through it.
- Add a DMCA badge to discourage casual copying.
- Make sure Google knows yours is the original: publish first, use a canonical tag (your SEO plugin does this), and keep internal links pointing to the post.
Frequently Asked Questions
Does duplicate content get a site penalized?
Not as a penalty in the usual sense. Google filters duplicates and shows one version, so the risk is that the copy outranks you or your page is filtered out. Large-scale scraped content on your own site can trigger a manual action, which is a different case.
Which duplicate content checker is free?
Google Search, DupliChecker, Plagiarisma, Small SEO Tools, Siteliner (up to 250 pages), and Google Alerts are free. Copyscape offers limited free URL checks.
How do I find duplicate content on my own website?
Run your domain through Siteliner. It lists pages that share text and shows the percentage of duplicate content across the site.
How do I check a guest post for plagiarism?
Paste the text into Grammarly, Quetext, or DupliChecker before publishing. If the writer used AI, Copyleaks or Quetext will flag that too.
Can I stop people from copying my content?
Not completely. Right-click blockers are easily bypassed and annoy readers. Focus on being recognized as the original (publish first, canonical tags, internal links) and on removing copies that outrank you.
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