Decide which NotebookLM you are actually replacing: a grounded chat over your sources, a notebook full of generated research notes, or a fast way to turn documents into briefs. NotebookLM keeps the retrieval pipeline, source parsing, prompting, and model choice out of sight; an open source tool forces those into the open. Open Notebook leans furthest toward the NotebookLM shape, with multi-notebook organization, source citations, and even multi-speaker audio summaries, while Khoj is built as a personal second brain with semantic search and agents, and SurfSense targets teams with shared, multiplayer notebooks and connectors into Drive, Slack, and other sources.
Expect to give up some polish. NotebookLM is built around a low-friction source workflow, generated summaries, and citations back to the material, and open source options match pieces of that while asking you to choose a model, configure ingestion, tune chunk sizes, and keep a database or file store healthy. Audio-style summaries exist - Open Notebook generates multi-speaker podcasts, and SurfSense lets you configure TTS models - but treat them as features to test rather than guaranteed parity, and check OCR and citation quality against your own messy documents, not a clean sample.
The migration itself is mostly a source-reconstruction job. Inventory each notebook, its source files, and the generated notes you rely on, then keep the original PDFs, transcripts, and web captures as your system of record and copy any summaries, briefs, or outlines you want to preserve into plain text or Markdown. Recreate each notebook as a collection in the new tool, re-ingest the sources, and verify citations against the originals before you trust an answer, cleaning up OCR errors, duplicate files, and broken captures as you go.