The AI Tool Shelf🤖 Best AI Assistants & Research Tools
General AI assistants and research tools that answer questions, write, analyse files and search the web. These are the most-used AI apps in the world, compared in plain English with their free plans and limits.
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Our top picks: Claude for writing, research and everyday office work; ChatGPT for anyone who wants one assistant for writing, research and everyday tasks; Gemini for people who live in Google apps (Gmail, Docs, Drive, Android); Perplexity for research and questions where you want sources you can check; DeepSeek for free reasoning and coding help for personal, non-sensitive use; Microsoft Copilot for Windows and Microsoft 365 users who want AI inside the apps they use; NotebookLM for students, researchers and creators working from their own documents.
Quick comparison
| Tool | Best for | Pricing | |
|---|---|---|---|
| Claude | writing, research and everyday office work | Free plan available; Pro from $17/month billed yearly ($20 monthly); Max from $100/month | Try ↗ |
| ChatGPT | anyone who wants one assistant for writing, research and everyday tasks | Free; low-cost Go plan in some regions; Plus $20/month; Pro from $100/month | Try ↗ |
| Gemini | people who live in Google apps (Gmail, Docs, Drive, Android) | Free; Google AI Plus $4.99/month; AI Pro $19.99/month; AI Ultra from $99.99/month | Try ↗ |
| Perplexity | research and questions where you want sources you can check | Free; Pro $20/month ($200/year); Max $200/month | Try ↗ |
| DeepSeek | free reasoning and coding help for personal, non-sensitive use | Free chat; API is paid | Try ↗ |
| Microsoft Copilot | Windows and Microsoft 365 users who want AI inside the apps they use | Free; Office features included with Microsoft 365 plans | Try ↗ |
| NotebookLM | students, researchers and creators working from their own documents | Free; higher limits with Google AI Plus ($4.99), Pro ($19.99) and Ultra plans | Try ↗ |
1. Claude
An AI assistant for writing, research, files and small apps.
Claude is the AI assistant made by Anthropic. Beyond chat, it searches the web, analyses uploaded files, creates Word, Excel, PowerPoint and PDF files, builds shareable documents, dashboards and small tools, remembers context across chats and connects to apps like Google Workspace and Slack.
Best for: writing, research and everyday office work
2. ChatGPT
OpenAI's all-round AI assistant, now with GPT-6.
ChatGPT is the most-used AI assistant in the world. It writes, answers questions, searches the web, analyses files and creates images. Since October 2026 it runs GPT-6 (Luna on Free and Go, Sol on paid plans), and answers can include interactive charts, forms and small tools.
Best for: anyone who wants one assistant for writing, research and everyday tasks
3. Gemini
Google's AI assistant, built into Gmail, Docs and Android.
Gemini is Google's AI assistant. It chats, searches with Google, writes and analyses documents, and works inside Gmail, Docs and Android. Free users get Deep Research, Gemini Live voice chat and Canvas; paid Google AI plans add higher limits, video generation, more storage and the top models.
Best for: people who live in Google apps (Gmail, Docs, Drive, Android)
4. Perplexity
An AI answer engine that searches the web and cites sources.
Perplexity answers questions by searching the web and showing its sources, which makes it popular for research and fact-checking. The Pro plan adds unlimited Pro searches, Deep Research, file uploads and a choice of models from OpenAI, Anthropic and Google.
Best for: research and questions where you want sources you can check
5. DeepSeek
A free AI chat with strong reasoning and open models.
DeepSeek is a Chinese AI company whose chat assistant is free to use, with no paid consumer plan. Its models are released with open weights and are strong at reasoning and coding. It is text-first, refuses some China-sensitive topics, and stores data in China, which matters for privacy and work use.
Best for: free reasoning and coding help for personal, non-sensitive use
6. Microsoft Copilot
Microsoft's AI assistant in Windows, Edge and Microsoft 365.
Microsoft Copilot is a free AI assistant built into Windows and Edge and available on the web and mobile. It chats, searches the web, creates images and, with a Microsoft 365 subscription, works inside Word, Excel, PowerPoint and Outlook.
Best for: Windows and Microsoft 365 users who want AI inside the apps they use
7. NotebookLM
Google's AI research notebook that turns your sources into podcasts.
NotebookLM (renamed Gemini Notebook in July 2026) lets you upload PDFs, docs, websites and videos, then ask questions answered only from those sources. It can turn them into Audio Overviews (podcast-style discussions), Video Overviews, mind maps, flashcards, quizzes and study guides. It is free with a Google account.
Best for: students, researchers and creators working from their own documents