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Synapsi vs NotebookLM

NotebookLM helps you read it. Synapsi makes you remember it.

NotebookLM is a free, trusted way to summarize and chat with your sources. But it has no spaced repetition, no mastery tracking, and no teach-back. Synapsi is the study loop that happens after you understand.

Summarize a source, then turn it into a quiz

Upload a PDF or paste a YouTube link. The summary comes back in sections, and one click makes flashcards or a quiz from the same source.

Free · no signup · no card

NotebookLM is excellent at understanding sources. It is not built to make you retain them. Synapsi picks up where it stops: FSRS review, an AI-judged Feynman teach-back, and a concept-mastery journey that runs until exam day.

FeatureNotebookLMSynapsi
PriceFree with a Google accountFree to start. Pro from $4 a month
Summarize and chat with your sources✓✓
Two-host audio overview✓Read-aloud only
Flashcards and quiz from a sourceSome accounts✓
Spaced repetition—FSRS
Feynman teach-back, judged by AI—✓
Mastery tracking per concept—✓
Mock exam across a whole folder—✓
Native mobile reviewLimited✓

Use NotebookLM to understand a pile of sources. Use Synapsi to make sure that understanding lasts past this week.

Free tools, no account

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Prove you actually learned it.

Free to start, no card. A 3-day free trial unlocks everything.