Compared
CastGenX vs NotebookLM Audio Overviews
NotebookLM Audio Overviews: Google's tool (renamed Gemini Notebook in July 2026) that turns your documents into a spoken overview: two AI hosts by default, or a one-voice brief, a critique or a debate. CastGenX: the one window for the whole episode. Here is where each one wins, with the numbers.
Side by side
| CastGenX | NotebookLM Audio Overviews | |
|---|---|---|
| Price | Free plan; paid from $39 | Free; $4.99–$19.99 for more use |
| Input | A brief, a topic, your own writing or sources | Your uploaded documents |
| Script you can edit | Yes, before and after voicing | No; change the prompt and regenerate |
| Length control | Exact length, ±5% | Shorter / Default / Longer presets, English only |
| Voices | Pick per speaker; clone your own | Fixed hosts; no voice picker |
| Interrupt the hosts | Yes, and it rewrites what comes next | Yes, in interactive mode; your part isn't kept in the audio |
| Music, SFX, mixing | Yes | No |
| Loudness mastering | −16 LUFS with a report | No spec published |
| Hosted feed, directories | Yes | No; download on the web, or share the whole notebook |
| Show notes, clips, posts | Yes | No |
| AI disclosure | Marker in the audio, feed tag, show-notes line | An inaudible watermark; nothing listeners see or hear |
| Usage limits | Credits a month by plan; the price is shown before each render | Refresh every 5 hours, with a weekly cap |
CastGenX: Free; Creator $39, Pro $69, Studio $149 a month (yearly $31/$55/$119); $49 lifetime codes on AppSumo, stack up to six. NotebookLM Audio Overviews: Free within usage limits that refresh every 5 hours up to a weekly cap; Google AI Plus ($4.99) and AI Pro ($19.99 a month) raise them. Read from the public pricing and feature pages on 3 October 2026. If we have something wrong, write to hello@castgenx.com and we'll correct it.
Where NotebookLM Audio Overviews is the better pick
- It is free and takes thirty seconds.
- Grounded in your documents: good for a quick summary you'll listen to once.
- Nothing to learn.
- 80+ languages, four formats and video overviews.
Pick NotebookLM Audio Overviews if
You want to hear a document explained while you drive, and nobody else will hear it.
Where CastGenX is the better pick
- It is a studio, not a summary. You control the script, the length, the voices and the mix.
- The result is a published episode: mastered, on a feed, with show notes and clips.
- Listeners can tell it's a show, and the feed says what AI did, which Apple's guideline 1.11 asks for in every episode's audio and metadata.
Pick CastGenX if
You are making a podcast other people subscribe to, and you need to control what goes out.
Questions
- Can I publish a NotebookLM Audio Overview as a podcast?
- You can download the file on the web and host it elsewhere, but you can't edit the script, set an exact length, add music, master it or get a feed. CastGenX does all of that from the same kind of brief.
- Is CastGenX free like NotebookLM?
- Not for good. Your first episode is on us (15 credits once, about 15 finished minutes), then a plan from $31 a month keeps the show going.
- Why do listeners care?
- Two-thirds of podcast listeners react badly to the idea of an AI replacing their host, and a third say they'd feel deceived (Edison Podcast Metrics, 2026). CastGenX marks the audio, tags the feed and writes the disclosure line, and lets you keep yourself in the show.