🔎 Use case
Best AI tools to research
Short answer: Use Perplexity. Fast cited answers. Free tier: Yes. Paid from $20/mo Pro. Alternatives: Gemini (Deep Research), NotebookLM.
Top pick: Perplexity
Fast cited answers. Official site: https://www.perplexity.ai
All options
Perplexity
Fast cited answers
Top pickFree tier$20/mo ProGemini (Deep Research)
Deep research; Gemini 4 Argon on Pro/Ultra
Free tier$19.99/mo Google AI ProNotebookLM
Grounded in your own sources
Free tier$4.99/mo via Google AI PlusGoogle AI Studio
Free playground for Gemini models, including Argon
Free tierPay-as-you-go API (Argon $2/$10 per 1M tGoogle Deep Review
Agentic technical-document reviewer; 2 free reviews/week, Gemini API beyond
Free tierGemini API pay-as-you-go beyond freeExa
Search and agent APIs built for LLM context with citations
Free tierPay-as-you-go from $4/1k Instant searche
Compare
| Role | Tool | Why | Free tier | Paid from | Last checked |
|---|---|---|---|---|---|
| Top pick | Perplexity | Fast cited answers | Yes | $20/mo Pro | no recorded check yet |
| Alt | Gemini (Deep Research) | Deep research; Gemini 4 Argon on Pro/Ultra | Yes | $19.99/mo Google AI Pro | no recorded check yet |
| Alt | NotebookLM | Grounded in your own sources | Yes | $4.99/mo via Google AI Plus | no recorded check yet |
| Alt | Google AI Studio | Free playground for Gemini models, including Argon | Yes | Pay-as-you-go API (Argon $2/$10 per 1M tokens intro) | no recorded check yet |
| Alt | Google Deep Review | Agentic technical-document reviewer; 2 free reviews/week, Gemini API beyond | Yes (2 reviews/week) | Gemini API pay-as-you-go beyond free [official, Oct 15] | |
| Alt | Exa | Search and agent APIs built for LLM context with citations | Yes ($10 credits/mo) | Pay-as-you-go from $4/1k Instant searches [official, Oct 15] |
Last checked is per tool (see the table). Page updated . Prices change, so confirm on the vendor's site.