# Zotero vs EndNote for Systematic Reviews The core difference in Zotero vs EndNote for systematic reviews is not reference storage, since both tools store, organize, and format thousands of citations competently. The difference is in workflow fit. Zotero is a free, open-source reference manager with strong collaboration features that deduplicates records with only fair accuracy. EndNote is a paid desktop reference manager with deep customization for large libraries that also deduplicates with only fair accuracy. The rule of thumb is simple. Either tool can serve as the bibliographic backbone of your review, but neither should be your only line of defense against duplicate records. Benchmark studies show that dedicated screening and deduplication tools such as Rayyan, Covidence, Mendeley, and the Systematic Review Accelerator outperform both Zotero and EndNote at finding duplicates, so the strongest workflow pairs one of these two reference managers with a purpose-built screening tool [1][2]. This guide walks through what each tool actually does, what the head-to-head evidence shows, where each one fits in a review workflow, and how to choose between them for your own project. ## What a Systematic Review Demands from Reference Software A systematic review is a research synthesis that follows a predefined protocol to identify, screen, and appraise all studies relevant to a specific question. The method is standardized under reporting frameworks such as PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses), which requires a flow diagram documenting how many records were identified, screened, excluded, and included at each stage. The volume of records is the defining challenge. A single review can identify thousands of records before screening even begins. A pharmacokinetics review that searched PubMed and EMBASE up to January 2026 screened the literature to identify 99 population pharmacokinetic models across 97 articles [3]. A dermatology review of multimodal imaging searched four databases, MEDLINE, Embase, CENTRAL, and Web of Science, using MeSH (Medical Subject Headings, the controlled vocabulary PubMed uses to index articles) and keyword combinations, and registered the protocol prospectively in PROSPERO, the international register for systematic review protocols [4]. A review of medical-financial partnerships searched both published and gray literature (reports, dissertations, and other materials outside commercial journals) over an extended period [5]. This volume creates four concrete demands on your software: 1. **Reliable import.** You will export records from multiple databases in RIS or other interchange formats and need every record to arrive intact. 2. **Deduplication.** The same article indexed in PubMed, Embase, and Web of Science arrives as three separate records. PRISMA requires you to report how many duplicates you removed, so the process must be countable. 3. **Transparent, repeatable steps.** Review protocols are registered and audited. Your deduplication and screening decisions need to be documented, not improvised. 4. **Clean export to screening tools.** Most teams screen titles and abstracts in Rayyan or Covidence, not in the reference manager itself, so the export format matters. Both Zotero and EndNote handle demand one and demand four well. They diverge on demand two, and that divergence is where the published evidence is most useful. ## Zotero and EndNote at a Glance **Zotero** is a free, open-source reference manager developed by the Corporation for Digital Scholarship, the same nonprofit organization behind the Zotero website and its browser connector. It runs on Windows, macOS, and Linux. Records are stored in a local library that syncs to Zotero's cloud service, and group libraries allow a review team to share a single collection of records with defined member permissions. Zotero integrates with Microsoft Word, LibreOffice, and Google Docs for inserting citations while you write. **EndNote** is a desktop reference manager developed by Clarivate, the company that also publishes the Web of Science database. It is sold as a perpetual desktop license (institutional site licenses are common) and ships with a companion cloud service, EndNote Online, for syncing and limited sharing. EndNote's "Cite While You Write" plugin is one of the most widely used Word integrations in academic writing. The desktop program offers extensive field-level customization, which matters for teams that need to track screening decisions, data extraction fields, or custom tags inside the reference library itself. One practical illustration of EndNote's continued role in published reviews comes from a 2025 exploratory systematic review of muscle flexibility training for chronic pain in older adults. That team searched Web of Science, PubMed, and Scopus, followed the PICOS framework (a structured way of defining Population, Intervention, Comparison, Outcomes, and Study design) and PRISMA 2020 guidelines, and used EndNote for reference management across a pool of 1,390 initial records [6]. ## Side-by-Side Comparison | Criterion | Zotero | EndNote | |--|--|--| | Cost | Free and open source | Paid desktop license, institutional site licenses common | | Developer | Corporation for Digital Scholarship | Clarivate | | Platforms | Windows, macOS, Linux | Windows, macOS (desktop), plus EndNote Online | | Word integration | Word, LibreOffice, Google Docs | Word (Cite While You Write), Pages | | Collaboration | Free group libraries with member permissions | Sharing limited by license and cloud account tier | | Deduplication method | Built-in duplicate detection against an existing library, matching on core fields | Built-in Find Duplicates with adjustable matching fields | | Deduplication accuracy in benchmark testing | Fair sensitivity, fair [positive predictive value](/blog/data-analysis/positive-predictive-value) [1] | Fair sensitivity, fair positive predictive value [1] | | Custom fields and organization | Tags and collections, plus note attachments | Highly customizable reference types and fields | | Export to screening tools | RIS and BibTeX export | Direct export, RIS, XML | | Learning curve | Short, interface resembles a web browser | Steeper, dense menus with more configuration options | | Best fit | Budget-limited teams, collaborative projects, mixed Linux/Mac/Windows teams | Large single-operator libraries, deep field customization, institutions with existing licenses | Neither row hides a decisive winner, and that is the honest headline of this research software comparison. The decisive evidence lives in the deduplication data, which deserves its own section. ## The Deduplication Evidence: Where Both Tools Fall Short ![Comparison of Zotero, EndNote X9 and Rayyan on deduplication sensitivity and positive predictive value from benchmark testing.](/article-images/illustrations/zotero-vs-endnote-for-systematic-reviews-dedup-accuracy.webp) Deduplication means identifying and removing duplicate records that represent the same study retrieved from different databases. Before any screening begins, PRISMA requires a count of duplicates removed, and an incomplete deduplication inflates your screening workload and can even let the same study enter the analysis twice. Two benchmark studies have tested Zotero and EndNote directly against a manually verified reference standard. The first study, published in the Journal of Clinical Epidemiology, ran a planned search across seven electronic databases through May 31, 2021, then compared automated deduplication tools against manual deduplication as the reference standard. The researchers measured sensitivity (the proportion of true duplicates the tool correctly flags), specificity (the proportion of true unique records the tool correctly leaves alone), negative predictive value (the probability that a record the tool calls unique really is unique), and positive predictive value or PPV (the probability that a record the tool calls a duplicate really is a duplicate) [1]. The results for the two reference managers were strikingly similar. EndNote X9 achieved a sensitivity of 0.73 (95% confidence interval 0.65 to 0.80) and Zotero achieved 0.74 (95% confidence interval 0.66 to 0.81), both classified as only fair. Their PPV values were also nearly identical and fair, 0.61 for EndNote X9 (95% confidence interval 0.54 to 0.69) and 0.62 for Zotero (95% confidence interval 0.54 to 0.69). Specificity across all tested tools ranged from 0.96 to 1.00, and negative predictive value ranged from 0.99 to 1.00 [1]. In plain language, both tools almost never delete a record that was actually unique, but both miss roughly a quarter of true duplicates, and about four in ten of the records they flag as duplicates are flagged in error. The same study found that three other tools performed substantially better. Rayyan reached a sensitivity of 0.98 (95% confidence interval 0.94 to 1.00), Mendeley 0.93 (95% confidence interval 0.88 to 0.97), and the Systematic Review Accelerator 0.90 (95% confidence interval 0.84 to 0.95). Mendeley and the Systematic Review Accelerator also produced good PPV, 0.93 and 0.99 respectively, while Rayyan's PPV of 0.41 was rated poor, meaning it overflags duplicates that a human must then confirm. The authors concluded that Rayyan, Mendeley, and the Systematic Review Accelerator were accurate enough for systematic review deduplication, and that the best choice depends on the tool's interface, its matching algorithm, and the transparency of the process [1]. The second study, published in Systematic Reviews, took a complementary approach. The authors built a heterogeneous benchmark set of references from topical searches in MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, and PsycINFO, deduplicated the set manually to create a gold standard, then ran the same records through Ovid multifile search, EndNote desktop, Mendeley, Zotero, Covidence, and Rayyan using default settings. They counted false-negative duplicates (real duplicates the tool missed) and false-positive duplicates (unique records the tool wrongly merged) for each method [2]. The findings reinforced the first study's central message. The most accurate methods overall were Ovid multifile search, Covidence, and Rayyan. Ovid and Covidence showed the highest specificity for identifying duplicates, while Rayyan showed the highest sensitivity [2]. Notably, EndNote and Zotero again did not rank among the top performers, this time in a comparison that also included the database vendor's own multifile deduplication and two professional screening platforms. Read together, the two studies converge on a clear practical conclusion. If deduplication accuracy is your primary criterion, Zotero and EndNote are functionally interchangeable, and both are inferior to Rayyan, Covidence, Mendeley, Ovid multifile search, or the Systematic Review Accelerator for this specific task [1][2]. The difference between Zotero and EndNote for systematic reviews therefore lies elsewhere, in cost, collaboration, customization, and the rest of the workflow. ## Where Each Tool Fits in the Review Workflow ![Five-step flow from protocol registration through searching, deduplication, screening and writing, marking which stages the reference manager covers.](/article-images/illustrations/zotero-vs-endnote-for-systematic-reviews-review-pipeline.webp) A modern systematic review pipeline typically looks like this: protocol registration, database searching, export and deduplication, title and abstract screening, full-text screening, data extraction, and writing. Zotero and EndNote occupy the search, storage, and writing stages, and their roles at each stage differ in character rather than in capability. ### Searching and Importing Both tools import RIS files cleanly from PubMed, Embase, Scopus, Web of Science, and the major databases. EndNote offers polished direct-export buttons inside Web of Science, which fits teams already working in the Clarivate ecosystem. Zotero's browser connector captures records directly from a web page, which speeds up supplementary searching, citation chasing, and gray literature collection. A review searching published and gray literature benefits from that kind of flexible capture, which is one reason broad-scope reviews often maintain search logs across both commercial databases and noncommercial sources [5]. ### Deduplication As covered above, use a dedicated tool for the main deduplication pass. A defensible workflow is to export your combined, unfiltered record set from Zotero or EndNote, run it through Rayyan, Covidence, Mendeley, or the Systematic Review Accelerator, record the number of duplicates removed, and import the deduplicated set into your screening platform. Some teams run a second, conservative manual pass on the records flagged as duplicates, because the PPV data show that even the best automated tools misclassify some records, and the choice of tool should factor in algorithm transparency [1]. ### Screening Neither Zotero nor EndNote is designed as a dual-reviewer screening platform. Rayyan and Covidence, which ranked among the most accurate deduplication methods in benchmark testing, are built for independent blinded screening by two or more reviewers with conflict resolution built in [2]. The efficient pattern is to treat your reference manager as the archive of record and the screening tool as the decision engine. ### Full-Text Assessment and Data Extraction EndNote's customizable reference types and fields let some teams track retrieval status and reviewer assignments inside the library itself, which reduces the number of separate spreadsheets. Zotero handles the same job with tags, colored tags, and saved searches, which are more flexible but less structured. For formal extraction, most teams graduate to a spreadsheet or a dedicated extraction tool regardless of which reference manager they chose. ### Writing and Citation Formatting This is where both tools are mature and the choice is a matter of taste. EndNote's Cite While You Write is deeply embedded in institutional workflows and handles very large documents reliably. Zotero's Word and Google Docs plugins handle the same tasks, and its style library covers the thousands of journal citation styles most teams ever need. A team drafting its review manuscript will be productive in either environment. ## When to Use Zotero Choose Zotero when any of the following describe your situation: - **Budget is the binding constraint.** Zotero is free, including group libraries, which matters for student-led reviews, teams in low-resource settings, and any collaboration where purchasing licenses for every reviewer is impractical. - **Your team spans operating systems.** Zotero runs natively on Linux, which EndNote does not support, alongside Windows and macOS. - **Collaboration is central.** A shared Zotero group library gives every co-author access to the same records, tags, and notes without per-seat licensing negotiations. - **You need open formats.** Zotero stores data in an open, documented SQLite database and exports cleanly to BibTeX, which matters for teams that also use LaTeX or want independence from any single vendor. - **Your review is methodologically transparent about deduplication.** Since you will run deduplication through a dedicated tool anyway, Zotero's fair built-in accuracy costs you little, because it is not carrying that load [1]. The "when to use Zotero" question often comes down to a single insight. Zotero's weaknesses in the systematic review evidence, namely its fair deduplication sensitivity and PPV, are exactly the weaknesses EndNote shares, and both are solved the same way, by pairing the reference manager with Rayyan, Covidence, Mendeley, or the Systematic Review Accelerator [1][2]. Once that pairing is in place, Zotero's free collaboration model becomes a genuine advantage rather than a compromise. ## When to Use EndNote Choose EndNote when these conditions hold: - **Your institution provides it.** Most large universities and health systems hold EndNote site licenses, and using an institutionally supported tool means access to local IT help, training sessions, and colleagues who can troubleshoot. - **You work with very large, highly structured libraries.** EndNote's customizable reference types and fields, and its tolerance for libraries of tens of thousands of records, suit long-running reviews and review teams that maintain a master library across multiple projects. - **Your collaborators live in Web of Science.** Direct export from Web of Science into EndNote is seamless, which shortens the search-to-library step for teams anchored in Clarivate tools. - **You want heavy customization inside the reference manager.** If you plan to track screening status, retrieval notes, or reason-for-exclusion codes within the library itself, EndNote's field-level configuration is more structured than Zotero's tag-based approach. - **Your co-authors expect it.** In many clinical and biomedical departments, EndNote is the default, and manuscript handoffs between co-authors go more smoothly when everyone uses the same tool. Published reviews continue to document EndNote in exactly this role. The flexibility training review mentioned above is one recent example, where EndNote managed the 1,390 records screened against PICOS criteria under PRISMA 2020 reporting [6]. Large, multi-database reviews in clinical pharmacology follow the same pattern, running broad PubMed and EMBASE searches whose combined yield lands in the reference manager before screening [3]. ## Worked Scenarios **Scenario 1. A three-person graduate student team reviewing a narrow clinical question.** No one holds an EndNote license. The team registers a protocol in PROSPERO, searches PubMed, Embase, and CENTRAL using MeSH and keyword combinations, and exports roughly 2,400 records. They import everything into a shared Zotero group library, export the combined set, run it through Rayyan for deduplication and blinded dual screening, and log the duplicate count for their PRISMA flow diagram. Zotero is the right call here, and the benchmark evidence says their deduplication accuracy was carried by Rayyan, not by their reference manager [1][2]. **Scenario 2. A hospital department's evidence synthesis unit.** The institution holds an EndNote site license, the lead librarian maintains a 40,000-record master library with custom retrieval-status fields, and all previous reviews in the department were built in EndNote. A new review extends an existing one, so continuity matters more than switching costs. The team deduplicates through the Systematic Review Accelerator or Covidence, then screens in Covidence with its high-specificity duplicate detection as a second filter. EndNote is the right call here, because institutional support and library continuity outweigh the cost of a license that the institution has already paid [1][2]. **Scenario 3. A mixed team of a methodologist, a clinician, and a biostatistician preparing a meta-analysis for journal submission.** The methodologist works on Linux, the clinician on a Mac, and the biostatistician wants BibTeX export for a LaTeX manuscript. Zotero serves all three environments natively, while EndNote would force the Linux user onto a web-only workflow. The team deduplicates with Mendeley, which showed both high sensitivity and good PPV in benchmark testing, then documents the tool choice in their methods section [1]. ## Common Mistakes and Limitations - **Trusting built-in deduplication alone.** This is the single most consequential error. With sensitivity around 0.73 to 0.74, both EndNote and Zotero miss roughly a quarter of true duplicates when run with default matching [1]. Every missed duplicate is a record your reviewers screen twice and, worse, a study that could slip into the analysis as two entries. Always run a second deduplication pass in a tool with demonstrated high sensitivity, and document both passes. - **Assuming higher sensitivity means a better tool outright.** Rayyan's sensitivity of 0.98 came with a PPV of 0.41, meaning it flags many records as duplicates that are not [1]. A tool that overflags creates its own manual review burden. Match the tool to whether your bottleneck is missed duplicates or false merges. - **Deduplicating after screening begins.** If reviewers screen a partially deduplicated list, duplicate records consume screening time and can produce inconsistent exclude decisions for what is really one study. Deduplicate fully before the first screening decision. - **Failing to record the deduplication method.** PRISMA reporting requires the number of duplicates removed, and journals increasingly ask which tool removed them. Record the tool, version, and settings at the time you run it. - **Confusing the reference manager with the screening platform.** Zotero and EndNote do not provide independent, blinded dual screening with conflict tracking. Teams that screen inside the reference manager lose the audit trail that dual screening platforms provide, and benchmark evidence shows those platforms are also more accurate at deduplication [2]. - **Letting the license dictate the science.** Because EndNote is paid and Zotero is free, some teams assume the paid tool is more accurate for review tasks. The benchmark data show their deduplication performance is statistically indistinguishable, so cost should be weighed against collaboration and support needs, not against accuracy claims [1]. - **The general limitation.** Every systematic review project has its own protocol, funder requirements, and institutional constraints, and the right software choice for one team may be wrong for another facing different requirements. ## Frequently Asked Questions ### Is Zotero or EndNote better for systematic reviews? Neither is clearly better overall, because benchmark studies found their deduplication accuracy to be nearly identical, with Zotero at 0.74 sensitivity and EndNote X9 at 0.73. The real choice depends on budget, operating systems, collaboration needs, and institutional support, and both should be paired with a dedicated deduplication or screening tool for best results. ### Can Zotero and EndNote remove duplicates automatically? Yes, both have built-in duplicate detection, but testing against manually verified benchmarks found that both miss roughly a quarter of true duplicates at default settings. Run a second pass with a tool such as Rayyan, Mendeley, Covidence, or the Systematic Review Accelerator, and document the process for your PRISMA flow diagram. ### Do I need a reference manager at all if I use Rayyan or Covidence? Yes. Rayyan and Covidence are screening and deduplication platforms, not long-term reference libraries. You still need Zotero or EndNote to store records, track full-text retrieval, and insert citations while writing the manuscript, with the screening platform handling the reviewer decisions in between. ### When should I use Zotero instead of EndNote? Use Zotero when cost is a constraint, when your team works across Windows, macOS, and Linux, or when free shared group libraries would simplify collaboration. Its open formats and Google Docs integration also suit teams that write in LaTeX or non-Microsoft tools. ### Does EndNote justify its cost for a single systematic review? If your institution provides a license, the cost to you is zero and its customization and support are worthwhile. For a one-off review with no institutional license and a small team, Zotero's free collaboration features cover the same workflow, and the accuracy evidence gives neither tool an edge. ### What is the best software combination for a systematic review? A well-supported pattern is Zotero or EndNote as the reference library, a database-level multifile search or a dedicated deduplication tool for the duplicate pass, and Rayyan or Covidence for dual screening. Ovid multifile search, Covidence, and Rayyan ranked as the most accurate deduplication methods in comparative testing, and Rayyan, Mendeley, and the Systematic Review Accelerator were judged accurate enough for review deduplication in a separate benchmark. ## Sources 1. [Deduplicating records in systematic reviews: there are free, accurate automated ways to do so.](https://pubmed.ncbi.nlm.nih.gov/36241035/) 2. [Considerations for conducting systematic reviews: evaluating the performance of different methods for de-duplicating references.](https://pubmed.ncbi.nlm.nih.gov/33485394/) 3. [Precision Dosing of Vancomycin: A Systematic Review of Population Pharmacokinetics Models and Comparative Evaluation of Software Tools.](https://pubmed.ncbi.nlm.nih.gov/42082885/) 4. [Noninvasive Multimodal Imaging and Its Role in Diagnosing Skin Lesions in Dermatology: A Systematic Review and Meta-Analysis.](https://pubmed.ncbi.nlm.nih.gov/40627274/) 5. [Medical-financial partnerships for improving financial and medical outcomes for lower-income Americans: A systematic review.](https://pubmed.ncbi.nlm.nih.gov/39650309/) 6. [The Influence of Muscle Flexibility Training on Chronic Pain in Older Adults: An Exploratory Systematic Review.](https://pubmed.ncbi.nlm.nih.gov/41295776/)