Perplexity
perplexity.ai
Answers a question by searching the web and footnoting every claim
Free tier
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notebooklm.google.com
Summarises only the sources you upload, and cites the exact passage.
A research notebook that answers strictly from material you provide — PDFs, Google Docs, pasted text, web pages, YouTube links — and footnotes every claim back to the passage it came from, which largely removes the invented-citation problem. It will also spin your sources into a study guide, a timeline, or an audio conversation between two synthetic hosts. It refuses to answer anything outside your uploads, which is simultaneously the point and the limitation.
AltFTool does this too
If you would rather not leave the site, Text Summarizer covers the same job here — free, no account, and it runs in your browser.
Open Text SummarizerQuestions
Free to use, but you have to register before it will do the job. Needs a Google account, and each notebook takes a fixed number of sources with a word cap per source.
Yes. NotebookLM sends your input to its own servers to process it. That is fine for public material; for anything containing personal data, use one of the on-device tools instead.
Needs a Google account, and each notebook takes a fixed number of sources with a word cap per source.
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perplexity.ai
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