FreemiumListed
Perplexity
Perplexity AI
An answer engine that responds to questions in plain language and cites its sources — free to use at perplexity.ai, with a paid Pro plan for more powerful models and higher limits on its deeper research modes.
Use-case guide
Best free AI tools for research
Answer engines with citations and tools that stay grounded in sources you give them — useful when you need to trust where an answer came from, not just read it.
4 tools worth trying
FreemiumListed
Google NotebookLM
Google's AI research and note-taking tool that answers from the sources you upload — documents, PDFs, slides, links — and cites them. Free at notebooklm.google with a Google account, it can even turn your sources into a spoken audio overview.
FreemiumVerified
Claude
Anthropic · Claude Sonnet 5
Anthropic's AI assistant for writing, research, and analysis — free to start at claude.ai, with paid Pro and Max plans for heavier use.
FreeListed
Kaggle
A free platform for data science and machine learning — public datasets, browser notebooks with free GPUs/TPUs, competitions, a model hub, and hands-on courses, at kaggle.com.
Every tool here has a genuine free tier and was checked by hand — see how listings are checked, or browse the whole directory.