KastorFlow vs ExtendLM

Feature by feature

ExtendLM's features as listed on its Chrome Web Store listing (version 2.7.52), read November 6, 2026. Its site, extendlm.com, showed no feature list when we read it that day. — means they don't mention it, not that it can't be done. The KastorFlow column is checked against the extension itself. Spotted something out of date? Tell us and we'll fix it.

What Gemini Notebook does without either

ExtendLM's strong side is bulk work. Here is how Gemini Notebook handled that on its own on November 6, 2026. Adding many links works. We pasted 7 links in one go, separated by spaces, and all 7 came in within about 30 seconds. One article was in the list twice, and it came in twice: Gemini Notebook doesn't catch duplicates.

Removing them doesn't. Each source is deleted from its own menu, with a warning that it can't be recovered. We found no way to delete several at once; the tick boxes beside sources choose what the chat reads, not what to delete.

Grouping is now partly covered: Auto-label sources by topic sorted our 8 sources in about 8 seconds, and Collections group notebooks. Bulk delete, duplicates and anything that runs on its own still need an extension.

What the differences mean in practice

On the everyday rows both lists say yes. The rows that differ are about the quality of what's in a notebook, and work that runs without you.

An audit tells you which sources to trust

Gemini Notebook doesn't rate sources. KastorFlow's audit checks each source two ways. It scores how relevant and how authoritative the source is for the notebook's topic, and it flags broken, cut-off or cluttered text with a score from 0 to 10, where under 6 is worth cleaning. It also rates five kinds of source, authority, academic, community, recent and practitioner, as strong, good, thin or missing. That helps once a notebook has grown past what you remember adding.

Enrich then finds sources for each gap. Nothing goes in until you tick it, and never more than the notebook has room for. Free and Pro include 1 audit and 1 enrich a month; Pro+ has no monthly limit. How the audit works

Room in a notebook: two approaches

ExtendLM's listing describes merging sources you already have into one, to stay under a notebook's source limit. KastorFlow doesn't merge existing sources. It checks the free slots before an import and starts nothing if the import won't fit.

A free notebook holds 50 sources, and a 40-video course added video by video fills 40 of them. KastorFlow can merge a playlist or a channel's recent uploads into one source, one for every 100 videos, which leaves 49 slots for papers and notes. The trade-off: you can't tick single videos inside a merged source. Free includes 1 merge a month, with a free sign-in; Pro includes 50. A playlist as one source

Duplicates

KastorFlow's Find duplicates sits beside the source list. It selects the extra copies that share a web address, or a name and size, keeps the first of each and deletes the rest after you confirm. It's on every plan.

Automations

ExtendLM's listing mentions automation and syncing with Google Drive files, but lists no triggers. KastorFlow's rules start on a tag, a new source, a schedule, or a finished audit, research build, YouTube import, Audio Overview, Studio artifact, podcast episode or Readwise sync. Automations are on Pro; notebook autopilot is on Pro+. Automations

Obsidian, Readwise and Anki

ExtendLM exports chats, notes and reports as Markdown, Word or PDF. KastorFlow's Obsidian connection goes both ways, and it connects Readwise, Slack and Discord. All four connections are on Pro+. It also sends Gemini Notebook's flashcards straight into an Anki deck, which Gemini Notebook itself can't export. Free includes 1 Anki send a month.

Try KastorFlow next to ExtendLM

You don't have to switch to compare them. KastorFlow works on the same Gemini Notebook tabs and Google account, and reads the notebooks already there. Nothing needs moving.

1. Add KastorFlow to Chrome. No account is needed to start.
2. Audit a notebook you know well. In KastorFlow, open Research & improve → Audit and enrich, choose the notebook and run the audit. See whether the flagged sources are the ones you would have dropped.
3. Try a playlist as one source. Open a YouTube playlist, click the KastorFlow icon in Chrome's toolbar, choose Import playlist as one source and pick the notebook. It checks the notebook has room before it starts.

• KastorFlow keeps its own tags, folders and collections. It doesn't change Gemini Notebook's labels or Collections, or anything ExtendLM has saved.
• Both can add buttons to the Gemini Notebook page. If something looks off, turn one off for a minute at chrome://extensions to see which it is.
• The library map and search across notebooks are free for 7 days, then need a free KastorFlow account.
• If you remove KastorFlow, your notebooks and the sources it added stay in Gemini Notebook.

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