Free plagiarism checker for your Spanish thesis and papers

Yes. You can analyze your documents without paying and without creating an account. The analysis runs on your own device, so there is no usage limit due to server costs.

The checker is built and tuned for documents written in Spanish: essays, theses and papers for Spanish classes, Spanish-speaking universities or bilingual programs. A document in English is still compared word for word with the web and the academic databases, but the encyclopedia search and the detection of paraphrases and translations are tuned for Spanish, so the report for an English document may be incomplete. The interface is available in English and Spanish.

No. Your file is read and analyzed inside your browser. To look for matches, only isolated phrases and keywords are sent to the public search engines of Wikipedia, Wikibooks and Wikisource and of open academic databases (OpenAlex, Crossref, Europe PMC, DOAJ, OpenAIRE, HAL, DataCite and LA Referencia), and to CORE, Semantic Scholar, Springer Nature, IEEE Xplore through our server, without being stored, and the text of your references to Crossref, OpenAlex and DataCite (Unpaywall and OpenCitations only receive DOIs); from the English Wikipedia articles are only downloaded, without sending it your text. If you turn on the whole-web search, short fragments of each sentence of your text (never more than 9 words in a row per search, never the document) and their keywords pass through our server, without being stored, to the AI and search services that make it possible, which search for them across the web and may keep them and use them to improve their services. Your last five analyses (with the corrections you apply), and the responses of those services so that analyzing again is faster, are stored only on your device for 24 hours and you can delete them whenever you want. While the analysis runs, the document is also stored there, so it can resume if interrupted, and it is deleted when it finishes. To compare it with papers by other students, only numeric fingerprints of your text travel and are stored, which cannot be used to rebuild it, never the text.

It is the part of your text that matches one of the sources checked, excluding what the filters leave out: quotations in quotation marks and block quotes, the bibliography and matches of fewer than 8 words. It is not an accusation: a properly marked and referenced quotation is not plagiarism.

Yes, with “Whole Web + AI” turned on. After comparing with the academic databases and the open encyclopedias, we search the whole web for every sentence of your text, from the beginning to the end of the document, including what those sources already explain (another page may be the origin): first with an exact-phrase search engine and, for what does not appear, with AI. The AI only suggests pages: we download each one, check that it contains the fragment (or its keywords together) and compare it in full, word by word, with your paper; only what truly matches counts. It is free for everyone, with or without an account; so that the daily quota is enough for everyone, each person has a number of web searches per day, and when that limit is reached the analysis is still completed with the other sources.

It detects verbatim and near-verbatim copying (text pasted as is or with changes in capitalization, accents, quotation marks or a few words) and flags possible paraphrases: sentences that repeat the idea of a source even if they change the order, the form or use synonyms, as automatic “paraphrasing tools” do. It also flags possible translations from English: we compare your text with every source found in English (academic articles, web pages and the English version of the encyclopedias) by cognates, numbers and proper names in the same order. Both are marked apart and are not counted in the percentage.

No. Letters from other alphabets that imitate Latin ones (such as a Cyrillic “е” instead of an “e”) are compared as the letter they imitate, invisible characters are removed and hidden text (white, hidden or tiny) is left out of the analysis. The report warns you if it finds any. If they appear in your paper without you putting them there, they usually come from copying and pasting from another page: review those fragments.

Yes. We cross-check the citations in your text in APA format (author, year) or numeric [n] with your reference list and warn you about citations without a reference, references you never cite and years that do not match. We also check in Crossref and OpenAlex that each reference exists, and we review the APA 7 format of the list: alphabetical order, year, DOI as a link, “Retrieved from” and “et al.” (which APA 7 no longer uses in the list) and repeated references.

Yes. Tap a highlight, choose to quote it verbatim, add the citation or rewrite it in your own words, adjust the text if you want and press “Apply to my text”: the correction goes into your corrected version and the source’s reference is added to your list. No correction is applied without its citation. Then analyze your version again with one tap or download it in Word (Times New Roman 12, double spacing, indented block quotes and references with a hanging indent, as APA 7 requires).

Yes, in Word documents: an indented paragraph of 40 words or more with its citation (author, year) at the end or announced in the previous paragraph counts as a quotation, and the quotation filter leaves it out of the percentage. An indent without its citation is not enough: indenting copied text does not turn it into a quotation.

The analysis continues. Without a connection it pauses and resumes on its own as soon as the connection returns, without losing what it already checked. If the page reloads, or the phone closes the tab in the background, it resumes automatically when you come back: meanwhile your document is stored only on your device, and it is deleted when the analysis finishes.

Yes. From the report tap “Fix and analyze again”: your text opens in the checker so you can edit it, or upload the corrected version of the file. The new report is compared with the previous one of the same paper and with the same filters: similarity, fragments that count and details to review, before and now. We keep your last five analyses only on your device, for 24 hours.

No. We removed the AI-generated text indicator: no AI detector is infallible and ours did not reach the reliability we require, so we prefer not to show you a figure that could mislead you. The plagiarism checker measures matches with real sources, which you can verify word by word.

Tap each highlight in the report. You can quote it verbatim with its APA 7 reference already formatted, or rewrite the idea in your own words while keeping the citation to the author, and apply it right there in your text. What you should never do is change words just so the checker does not see it: that is still plagiarism.

With the original file, yes: a scanned PDF is an image and has no text to compare, so upload the Word file or the PDF exported from your word processor and we analyze it in full.

It is your check before you submit: you find and fix the matches before handing in your paper, with a complete originality report in PDF. Each university uses its own tools and databases, so whatever is not in the sources we check does not appear in our report.