Research happens in the browser now. You read papers in tabs, chase citations across PubMed and Google Scholar, annotate PDFs inline, and run half a literature review without ever opening a desktop app. The problem is that browsers were built for casual reading, not for multi-week projects that span hundreds of tabs and dozens of sources. One crash, one restart, one switch to the laptop, and the working context is gone.
This guide is organized by the job each extension does rather than by a ranked list, because researchers rarely need a single winner — they need one good tool per layer. Nothing here is crowned best overall. Pick the layers where your workflow actually leaks.
Session memory: Blackmount (that's us)
Blackmount handles the layer most research stacks ignore. Reference managers capture individual items — a paper, a citation, a highlight. Blackmount captures the whole working state: every tab open at a given moment, plus the notes and voice recordings you attach to explain why those tabs were open. Save a session on the office desktop, restore it on the laptop at home.
The voice note is the part researchers tend to keep. Forty tabs deep in a review and about to step away, you record ten seconds: "These five are the transformer architecture papers for the methods section — the third one has the figure I need." Weeks later the session comes back with that context attached instead of a wall of anonymous titles. Saved sessions are searchable, including AI chats you have captured from ChatGPT, Claude, Gemini and others, which matters more every year as chat threads become part of the research trail.
It runs on Chrome, Firefox, Edge, Brave, Vivaldi, and Opera, plus iPhone. Guest Mode is free, works offline, and needs no account; Pro is $0.99/month and adds cloud sync across devices. The honest limits: Blackmount is not a reference manager and not a PDF annotator. It will not generate a bibliography or let you highlight inside a paper. If you work in short bursts on one machine, you probably do not need it. If you routinely reopen the same twenty tabs on a different computer, see how cross-device tab restore works.
Citations: Zotero Connector, Mendeley Web Importer
Zotero Connector is the reference layer most researchers should start with. It detects citable resources on a page — journal articles, books, patents, news — and saves them to your library in one click, pulling title, authors, journal, DOI, and date automatically, and grabbing the full-text PDF when it is available. Zotero itself is free and open source; paid cloud storage starts around $20/year once the 300 MB free tier fills up, which happens fast if you save PDFs. Word, Google Docs, and LibreOffice integration means citations flow through to the manuscript without retyping.
Mendeley Web Importer does much the same job with tighter Elsevier integration (ScienceDirect, Scopus), which is a real advantage in fields that live in those databases. Free tier includes 2 GB; premium starts around $4.99/month. No Safari support. If you have no institutional pull toward Elsevier, Zotero's open-source ecosystem is the easier long-term bet.
Paper access: Unpaywall
Unpaywall is free, tiny, and worth installing before anything else on this list. When you land on a paywalled article, it searches an index of over 20 million legal open-access full texts and, if a version exists in a repository, preprint archive, or on the publisher's own site, drops a green tab on the edge of your screen linking straight to the PDF. Everything it surfaces is authorized green open access, not piracy. Coverage depends on whether someone deposited a copy, and it is Chrome and Firefox only.
Annotation and highlighting: Hypothesis, Glasp, Liner
Hypothesis is the strongest choice when annotation is a group activity — reading groups, peer review, seminar work. Annotations can be private, public, or scoped to a group, and they support rich formatting including LaTeX. Two things to know: outside Chromium browsers you are on a bookmarklet, and annotations default to public until you change the setting.
Glasp (free, Pro around $10/month billed annually) adds an AI layer over your highlights across pages, PDFs, and YouTube, and shows what other readers highlighted on the same page. The social-by-default posture does not suit unpublished or sensitive work. Liner offers a similar highlight-plus-AI-copilot experience on Chrome and Edge, but at roughly $16.67/month billed annually it is hard to justify unless the copilot genuinely replaces a separate AI subscription.
Clipping and bookmarking: Notion Web Clipper, Raindrop.io
Notion Web Clipper is the right call if Notion is already your knowledge base — you file a page directly into the correct database with properties set at capture time. It does not extract academic metadata the way Zotero does, and adopting Notion solely for the clipper is not worth it.
Raindrop.io (free, Pro around $3.54/month) is a genuinely good bookmark manager: nested collections, tags, previews, and full-text search across saved pages on Pro, which is how you find the paper you saved three months ago and tagged badly. It saves individual URLs, not sessions, and offers no citation export. If you came here after Pocket shut down, the Pocket alternatives comparison covers this category in more depth.
PDF reading: Google Scholar PDF Reader, Scholarcy
Google Scholar PDF Reader is free and makes in-browser paper reading meaningfully better: a generated outline for navigation, in-text citations you can preview without leaving the page, jump-to-figure links, highlighting saved to your Scholar library, and proper dark and night modes. Chromium browsers only, and it is a reading tool rather than a reference manager.
Scholarcy turns a paper into summary flashcards with extracted study details and links to open-access versions of its references — useful for triage during a wide review. The free extension has usage limits, and its summaries are AI-generated: fine for deciding what to read, never a substitute for reading what you cite.
AI literature search: Elicit, Semantic Scholar
Elicit is a web app rather than an extension, but it earns a place here because it does the part of a systematic review that is pure labor: searching across more than 125 million papers, filtering by criteria, and extracting comparable data points across studies into a table. Free tier is a one-time credit allowance; paid plans run about $10-12/month. Verify every extracted value against the source before it reaches a manuscript.
Semantic Scholar is free, and its extension is a thin but frictionless bridge: highlight a title, keyword, or author anywhere and search it instantly, then follow the citation network, save to your library, or read the TLDR summary. The depth is in the platform — research feeds that learn from your library — more than in the extension itself.
Quick comparison
| Tool | Layer | Price | Cross-device sync | AI features |
|---|---|---|---|---|
| Blackmount | Session memory | Free / $0.99 mo | Yes | Yes |
| Zotero Connector | Citations | Free (paid storage) | Via Zotero | Via plugins |
| Unpaywall | Paper access | Free | — | — |
| Hypothesis | Annotation | Free / team plans | Yes | — |
| Raindrop.io | Bookmarking | Free / ~$3.54 mo | Yes | Some |
| Google Scholar PDF Reader | PDF reading | Free | Via Scholar | Yes |
| Elicit | Literature search | Free tier / ~$10 mo | Yes (web app) | Yes |
Pick by workflow
- Writing a dissertation → Zotero Connector for citations, Elicit for the review, Google Scholar PDF Reader for reading, Blackmount for keeping each chapter's tab context separate.
- Collaborative or seminar work → Zotero shared libraries plus Hypothesis groups.
- Triaging a large literature → Elicit and Semantic Scholar for discovery, Scholarcy for fast screening.
- Spending nothing → Zotero Connector, Unpaywall, Hypothesis, Semantic Scholar, Google Scholar PDF Reader, and Blackmount in Guest Mode.
- Research that spans devices → any citation manager you like, plus something that restores the whole session, not just the links.
Pricing and browser support change often. Spotted an inaccuracy, or a tool we should add? Email support@blackmount.ai — we update this post as tools ship new versions.