Zotero vs Mendeley: storage, Word and moving a library

Two tools, two ways of describing themselves

Zotero’s home page calls it “free, easy-to-use” and says it helps you collect, organize, annotate, cite and share research, on Mac, Windows, Linux, iOS and Android. It also says Zotero is open source and developed by an independent, nonprofit organization. Zotero’s storage page adds that the cost of developing, maintaining and supporting its services is funded by storage subscriptions from individuals and organizations.

Mendeley’s home page calls it “The free all-in-one reference manager”. It offers a download or Mendeley Web, mentions 2GB of free storage, and points to LeapSpace, which it describes as an AI research companion. Both descriptions come from the programs’ own pages.

Northwestern University Libraries, in a guide updated on 22 September 2026, says that EndNote, Mendeley and Zotero can all store references in one place, export citations from databases, format them in MLA, APA, Chicago and other styles, keep reading notes linked to sources, and insert citations into Word. The guide says you cannot go wrong with any of the tools. Belmont University Medical Library, in a guide updated on 15 November 2024, lists similar shared abilities and adds working offline and sharing references with a group. EndNote is a third option on both guides; this page compares only Zotero and Mendeley.

Storage: 300 MB and 2 GB are not the same kind of number

Zotero’s storage page, read on 30 October 2026, lists 300 MB of Zotero Storage for free. The paid tiers on it are 2 GB for 20 US dollars a year, 6 GB for 60 and unlimited for 120. Zotero’s documentation page on individual storage, last updated in 2017, lists the same prices. Mendeley’s home page says “Enjoy 2GB of free storage”. Belmont’s table gives the same pair: 300 MB cloud storage for Zotero, and for the free version of Mendeley 2 GB of personal storage.

The two figures do not measure the same thing. Zotero’s sync page splits syncing in two. Data syncing covers library items, notes, links and tags, everything except attachment files, and the page says it “is free and unlimited”. The 300 MB is for the attachments: PDFs, audio and video files, images. Belmont’s table adds limits on the Mendeley side that a headline of 2 GB leaves out: its free version allows 5 groups of up to 25 collaborators, with 100 MB of shared storage across all groups. On the Zotero side, Zotero says group file storage always draws from the storage account of the group owner.

Zotero describes a second route for files. Instead of Zotero Storage you can use WebDAV, a standard protocol, for your personal library; the page says group libraries cannot use it. Zotero also warns against one shortcut. Keeping the Zotero data directory inside a cloud storage folder, it says, is “extremely likely to corrupt” the database. For people who want their own file sync, it names two alternatives: copying the whole data directory by hand with Zotero closed, or using linked files kept in an externally synced folder. Mendeley’s home page and Belmont’s table describe its storage as an online account, or a local app with web-based syncing.

Belmont’s table also lists, for both programs, working offline: yes for Zotero and, for Mendeley, yes with Mendeley Reference Manager. Among Zotero’s weaknesses the same table lists limited free storage. The pages we read do not say how many PDFs fit in 300 MB or in 2 GB, so the comparison stops at the numbers each page prints.

Writing: Word, LibreOffice and Google Docs

Zotero’s home page says it creates references and bibliographies for any text editor, and directly inside Word, LibreOffice and Google Docs, with support for “over 9,000 citation styles”. Its page on word processor plugins, last updated in July 2023, says the plugins for those three programs create dynamic bibliographies: insert a new in-text citation and the bibliography updates, and correct an item’s title in the library and a click carries the change into your documents. The plugins are bundled with Zotero and installed automatically when it first starts, and they can be reinstalled from the Cite pane of the preferences. The page adds that third-party plugins exist for other word processors.

For Mendeley, the page we read in most detail is Mendeley’s own blog post of 22 February 2022, which carries a notice that it is outdated. It describes Mendeley Cite, an add-in for Microsoft Word, as compatible with Office 365, Word 2016 and newer, the Word app for iPad and Word for the web. The post says the whole document stays visible while you find and insert references, and that, because the library is stored in the cloud, Mendeley Cite works even without the desktop version installed. Belmont’s table of 2024 lists Word 2016 and above, Office 365 and the Word app for iPad for Mendeley, without Word for the web. Mendeley’s own pages and the Belmont table name only Word for Mendeley; Paperguide, a company page, says Mendeley Cite works with Word and LibreOffice and lacks Google Docs, while Zotero’s pages name Google Docs.

Styles and phones are where the dates matter. Zotero’s home page gives over 9,000 styles; Belmont’s table of 2024 gives a figure above ten thousand for Zotero and says Mendeley comes with the 10 most common styles and lets you install more. The two counts come from different pages written at different times, and the pages we read do not reconcile them. On phones, Zotero’s home page lists iOS and Android. Belmont’s 2024 table says the Apple app is from Zotero’s developer and the Android apps are third-party, and says apps from Mendeley were discontinued, with a third-party solution. Zotero’s home page carries no date, while Belmont’s table is from November 2024.

For collecting sources, Zotero’s home page says it senses research as you browse the web, and names JSTOR, arXiv, a news story and a library book as examples. Mendeley’s 2022 post describes Mendeley Web Importer as a browser extension for building a library while you search online, with one-click access to full text where it is available.

What happened to Mendeley Desktop

Two dated posts on Mendeley’s blog tell the story, and they point in different directions. On 22 February 2022, Mendeley introduced Mendeley Reference Manager, an app for desktop and web with collections, tags, a notebook for annotations and private groups, alongside Mendeley Cite and Mendeley Web Importer. The post says Reference Manager will replace Mendeley Desktop in the long run. From 1 September 2022, it says, users could no longer download and install Mendeley Desktop, while existing users could keep signing in, using and syncing. It adds that once Mendeley was confident the new app met users’ needs, it would begin the process of stopping all sign-ins to Mendeley Desktop, with plenty of notice.

On 9 July 2025 a second post is titled “Mendeley Desktop is Here to Stay”. It says many users told Mendeley they were not ready to switch, and that although there will be no new feature development for Mendeley Desktop, Mendeley will keep providing essential maintenance support, including critical security issues. It links a download again and names 1.19.8 as the latest version. It also says Mendeley will focus its future updates on Mendeley Reference Manager, that transitioning is not risky, and that you should sync your Mendeley Desktop library to the cloud before signing in to the new app.

Zotero describes the same history from the other side. Its page on importing from Mendeley says Elsevier began encrypting the local Mendeley database in 2018, a few months after Zotero announced work on a local importer. It says the export formats Mendeley supports do not contain folders, some metadata fields or PDF annotations, and it calls Mendeley Reference Manager “a wrapper around the website”. Mendeley’s 2022 post, by contrast, speaks of “identical desktop and web versions” and of automatic sync that backs up your latest changes in the cloud. These are Zotero’s words about Mendeley and Mendeley’s words about its own product, and we report them as claims. We opened neither program.

Moving a library between them

Zotero’s page on importing from Mendeley, updated on 25 August 2025, says Zotero can directly import all data, including the full folder structure, from an online Mendeley library. Before you start, all data and files must be synced to Mendeley’s servers. With Mendeley Reference Manager they already are; with Mendeley Desktop the page says to check your sync settings and confirm you can open your PDFs in your online Mendeley library. Then, in the latest Zotero, choose File, Import and the Mendeley Reference Manager option labelled “online import”. You log in to Mendeley to allow the import, and Zotero says your Mendeley password is never seen or stored.

The page lists what does not come across cleanly. Group libraries cannot be imported directly: copy the group’s items to a collection in your own Mendeley library first, then create a Zotero group and drag the imported collections into it. Fields that are not valid for a given item type are placed in Zotero’s Extra field. A Mendeley account that needs institutional credentials may need a separate personal account linked to the institutional one. For people who cannot use the online import, the page names an alternative: installing an old version of Mendeley Desktop from before the local database was encrypted, with the same requirement that everything be synced first.

Documents already written in Word are a separate question. Zotero says its Word and LibreOffice plugins can read citations created by Mendeley Desktop and relink them to the imported items. Citations created with Mendeley Cite, it says, are not readable by Zotero. Before Zotero 6.0.19, released in December 2022, the Desktop citations were readable but not linked; the page says anyone who imported with an earlier version must repeat the import once and select “Relink Mendeley Desktop citations”.

Zotero’s general page on moving lists import from EndNote, Citavi, BibLaTeX and JabRef, and says other tools, such as Reference Manager, RefWorks and Papers, can be brought in by exporting to RIS, BibTeX or CSL JSON. The pages we read give no steps for importing a Zotero library into Mendeley; Zotero’s import page only says that Mendeley Desktop had imported data from Zotero’s own open database since 2009. Northwestern’s guide says switching between tools is possible, but becomes less convenient the longer you use one and the more file attachments you collect.

What the libraries and the sellers say

Northwestern gives each program a reason. For Mendeley: if your research content is mainly PDF files, it has an integrated PDF viewer and can create citation records with its browser extension, and the guide calls its website and community platform the strongest. For Zotero: if your content is diverse, it is the easiest way to gather records for sources that are not PDFs. The guide says Zotero’s single-click capture works with more databases, catalogs and websites than Mendeley’s browser extension, that you can enable retrieval of PDF metadata so that dragging a PDF in creates a record, and that Zotero is open source and cannot be acquired by a company.

Belmont reaches the same split two years earlier. It calls Mendeley a great choice if your research content is mainly PDF files, with PDFs easy to drag in and good annotation features, and notes that the free version is limited to sharing five groups at a time; its weaknesses row for Mendeley adds that PDFs can only be shared when sharing an entire library, and that organization is limited to Group Sets and Groups. For Zotero it lists open source and unlikely to be bought or sold, easy sharing of PDFs in a group, archiving web pages and collecting varied non-article sources, automatic metadata when you drag a PDF in, and free use now and after graduation.

Two pages from companies that sell their own software also compare the pair. Paperguide’s post of 22 May 2026 carries a disclaimer that Paperguide offers research software that may compete with the products mentioned. It concludes that Zotero is the better overall reference manager for most researchers in 2026, citing its open-source ecosystem, citation support, Google Docs integration, Linux compatibility and offline use, and says Mendeley stands out mainly for AI-powered reading and library analysis. Paperpile, which publishes a reference manager of its own, updated its comparison on 10 September 2026; its section headings say Mendeley offers more cloud storage than Zotero on its free plan, Zotero has more sophisticated search and more flexible sharing, and Mendeley has a more user-friendly interface. We use both as readings from a party with something to sell, not as measurements. Paperpile’s score table lost its check marks when we read it, so we took nothing from it.

Put side by side, the pages turn on two questions. One is which word processor you write in, which is where Zotero’s plugin pages and Mendeley’s own pages, which name only Word, differ. The other is whether your sources are mostly PDFs or a mix of web pages, books and articles, which is where both libraries split. The pages we read do not say which of the two has the better citation insertion.

What we did not read

We installed neither program and moved no library. We did not open the Reddit thread, the Zotero forum thread or the blog and comparison pages from Effortless Academic and Casrai. Four support pages on Elsevier’s help site, about Mendeley’s account, installation and migration, reached us as empty shells, and Mendeley’s export guide reached us as a very short page, so we left those pages out and give no Mendeley paid-plan prices. The two Mendeley blog posts reached us with a loading placeholder in their text, so we do not say what they leave out. We did not open the other tabs of the Northwestern guide, among them the one on switching among tools, and we read the Belmont table’s developer row as unreliable and skipped it.