NotebookLM
Google's grounded notebook — it only answers from the sources you give it.
Tier 2 ToolsFreemium
Research Database Directory
Every research database, reviewed.
Perplexity
An answer engine with footnotes — fast orientation, not a citable source.
Tier 2 ToolsFreemium
Paperpal
Academic language editing trained on the literature, not on general prose.
Tier 2 ToolsFreemium
Scopus AI
Elsevier's generative layer over Scopus — summaries grounded in indexed literature.
Tier 2 AcademicSubscription
Ai2 Asta
Open agentic literature search from the lab behind Semantic Scholar.
Tier 2 Open AccessFree
Web of Science Research Assistant
Clarivate's AI assistant inside the oldest of the big citation indexes.
Tier 2 AcademicSubscription
ASReview
Open-source active learning that reorders your screening pile as you work.
Tier 2 ToolsFree
OpenCitations
Citation data as public infrastructure — CC0, queryable, no licence required.
Tier 2 Open AccessFree
VOSviewer
The bibliometric map-maker — turn citation data into readable networks.
Tier 2 ToolsFree
Covidence
The systematic-review workflow — screening, extraction, and team collaboration.
Tier 2 ToolsFreemium