ASReview
Open-source active learning that reorders your screening pile as you work.
Tier 2 ToolsFree
Research Database Directory
Every research database, reviewed.
OpenCitations
Citation data as public infrastructure — CC0, queryable, no licence required.
Tier 2 Open AccessFree
Ai2 Asta
Open agentic literature search from the lab behind Semantic Scholar.
Tier 2 Open AccessFree
Perplexity
An answer engine with footnotes — fast orientation, not a citable source.
Tier 2 ToolsFreemium
Primo Research Assistant
The AI layer in the library search box most students meet first.
Tier 3 AcademicSubscription
CiteSpace
Detect the turning points in a field — citation analysis with a temporal lens.
Tier 3 ToolsFree
RefWorks
The library-provisioned reference manager — web-based and institution-backed.
Tier 3 ToolsSubscription
VOSviewer
The bibliometric map-maker — turn citation data into readable networks.
Tier 2 ToolsFree
Bibliometrix
Bibliometric analysis in R — reproducible science mapping, code-first.
Tier 3 ToolsFree
Scilit
A fast, free scholarly index — MDPI's comprehensive metadata search.
Tier 3 Open AccessFree