Paperguide records 371,972 monthly visits with -2.9% month-over-month growth and Freemium pricing. Three Sigma records 416 monthly visits with -79.2% growth and Free Trial, Paid pricing.
AI-native workspace for literature reviews and auditable systematic reviews
AI document research that shows you exactly how it found each answer
| Dimension / Metric | ||
|---|---|---|
| Official Domain | paperguide.ai | threesigma.ai |
| Pricing Model | Freemium | Free Trial, Paid |
| Monthly Visits | 371.97K (371,972) | 416 (416) |
| MoM Traffic Delta | -11.05K (-2.9%) | -1.58K (-79.2%) |
| Primary Market & Share | 🇺🇸 United States (25.6%) | 🇺🇸 United States (100%) |
| Direct Visits / mo | 121.59K | 163 |
| User Rating | 4.4 | 4.3 |
| Supported Platforms | Website | Website |
AI-native workspace for literature reviews and auditable systematic reviews
Ask a research question in plain language and get a synthesized answer drawn from PubMed, arXiv, OpenAlex and Semantic Scholar, with every claim linked to its source paper.
Run PRISMA-style reviews with a predefined protocol, recorded screening decisions, dual independent reviewers and a conflict resolver, and a PRISMA diagram generated from your actual counts.
Import from Zotero or Mendeley, add papers by DOI, and get metadata and open-access PDFs fetched automatically, with annotations and notes that feed every other workflow.
Define custom extraction columns and have AI fill them across many papers, with each value linking back to the sentence it came from, exportable to CSV or Excel.
AI document research that shows you exactly how it found each answer
Point the tool at a folder of files and ask questions across the whole set at once, rather than opening documents one by one.
Whenever it answers, Three Sigma shows you how it reached the answer, so results are verifiable rather than a black box.
Access Three Sigma through a plugin from within an existing ChatGPT account on every plan.
No document on hand? A free solo mode works like a normal chat assistant.
Real-time AI answer engine and research workspace combining live web citations with frontier reasoning models.
Real-time AI answer engine and research workspace combining live web citations with frontier reasoning models.
A free, AI-powered academic search engine for 240M+ papers across every scientific field
A free, AI-powered academic search engine for 240M+ papers across every scientific field
AI academic search engine for peer-reviewed science
Offers robust PDF analysis and literature search workspaces, but lacks advanced systematic review screening workflows.
Offers robust PDF analysis and literature search workspaces, but lacks advanced systematic review screening workflows.
AI research assistant for evidence-based literature review and synthesis
Stronger AI academic writing and autocomplete assistance, but less comprehensive for systematic literature mapping.
Stronger AI academic writing and autocomplete assistance, but less comprehensive for systematic literature mapping.
SpecialistIndustry standard for systematic review screening and deduplication, but weaker on AI writing generation.
SpecialistIndustry standard for systematic review screening and deduplication, but weaker on AI writing generation.
Chat with any PDF, video, or website and get cited answers in seconds
SpecialistExcellent smart citation analysis to verify if papers support or dispute claims, but narrower writing capabilities.
SpecialistExcellent smart citation analysis to verify if papers support or dispute claims, but narrower writing capabilities.
Free / Open-sourceFree visual research discovery and literature mapping tool, but offers less automated evidence synthesis and writing.
Free / Open-sourceFree visual research discovery and literature mapping tool, but offers less automated evidence synthesis and writing.
A free AI answer engine that cites its sources
A free AI answer engine that cites its sources
SpecialistUnmatched visual literature discovery and graph mapping, but lacks document drafting and reference management features.
SpecialistUnmatched visual literature discovery and graph mapping, but lacks document drafting and reference management features.
