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Thunder Kitty vs Fathom
Fathom records your Zoom calls. Thunder Kitty records everything.
Fathom is the most generous free meeting tool on the market. Unlimited recordings, unlimited transcription, fast AI summaries, video replay, and a free plan that actually works — no minute caps, no trial expiration. It's genuinely excellent at what it does.
What it does is record your scheduled online meetings. Zoom, Google Meet, Microsoft Teams. That's the scope.
Thunder Kitty records anything that makes sound on your Mac.
At a glance
| Thunder Kitty | Fathom | |
|---|---|---|
| Transcription | Apple SpeechAnalyzer — on your Mac | Cloud (Fathom's servers) |
| Bot joins your call | No | Optional — bot-free mode in beta |
| Works in airplane mode | ✓ | ✗ |
| Video recording | ✗ | ✓ |
| Audio sources | Any system audio | Zoom, Meet, Teams only |
| Phone calls + FaceTime | ✓ | ✗ |
| In-person conversations | ✓ | ✗ |
| Languages | English | 28 |
| Speaker diarization | Named, with voice enrollment | ✓ |
| Your files | Plain .md in ~/Documents | In Fathom's database |
| AI training on your data | No | No |
| AI summary limit | Unlimited | 5/month (free) / unlimited (Premium) |
| Price | $10/month | $20/month (Premium) |
What Fathom does that Thunder Kitty doesn't
Video recording. When a meeting ends in Fathom, you have the full recording alongside the transcript — and every line of the transcript is linked to its timestamp. Click any sentence and jump directly to that moment in the video. For sales calls, client reviews, or any meeting you might need to replay, that's genuinely useful.
Fathom also has a free plan that isn't a trick. Unlimited recording and transcription, forever. The only meaningful limit is AI summaries — capped at five per month on the free tier. If you attend more than five meetings a month that need summaries, Premium is $20/month.
28 languages. Mobile apps. Team collaboration features. A searchable library across your entire meeting history.
And one more thing worth saying plainly: Fathom doesn't use your data to train their AI models. No opt-out required. For a cloud-based tool, that's a meaningful commitment.
What Thunder Kitty records that Fathom can't
Fathom connects to your calendar and joins your scheduled Zoom, Meet, or Teams calls. That's the workflow it's built for.
Thunder Kitty captures any audio playing through your Mac. A Zoom call, yes — but also a FaceTime conversation. A phone call on your Mac. A recorded interview you're playing back. An in-person meeting where your Mac is sitting on the table. A voice memo you want transcribed. Anything.
There's no calendar required. No integration to set up. No meeting platform to be compatible with. If it makes sound on your Mac, Thunder Kitty can transcribe it.
Two different ideas about what a meeting tool should be
Fathom is built around the scheduled online meeting as the primary unit of work. It joins, it records, it summarizes, it stores. The workflow is: calendar event → Fathom joins → summary in your inbox.
Thunder Kitty is built around the notepad as the primary unit of work. You open it when you need it, write what you want to write, and the transcript is there alongside your notes when the conversation is over. The workflow is: you're having a conversation → you open Thunder Kitty → you have a record.
Fathom is better if your most important conversations happen in scheduled video calls and you want them captured automatically. Thunder Kitty is better if your most important conversations happen everywhere — and you want a private, permanent record that lives on your Mac.
On files
When a meeting ends in Thunder Kitty, your notes and transcript sit in ~/Documents/Thunder Kitty Notes/ as a plain markdown file. Open it in any app. Point Claude at the whole folder and ask questions across every conversation you've ever recorded.
Fathom's recordings and transcripts live in Fathom's database. The product is excellent, but the archive is theirs.
Which one is right for you?
Thunder Kitty, if…
- Your important conversations happen everywhere — phone calls, FaceTime, in-person, any platform
- You want your transcripts as plain files, owned outright, readable anywhere
- Your meetings involve information that shouldn't leave your Mac
- You prefer a notepad that transcribes over a recorder that takes notes
Fathom, if…
- Your important conversations happen only in Zoom, Meet, or Teams
- You want video replay with transcript-linked timestamps
- You want a free plan with unlimited recording before committing to a paid tool
- You need 28 languages or team collaboration features
Common questions
Why is Thunder Kitty less expensive than most cloud transcription tools?
Because there’s no cloud infrastructure to run. Cloud transcription tools pay per audio minute for Deepgram, AssemblyAI, or Whisper API calls — that cost gets passed through your subscription. Thunder Kitty uses Apple’s on-device SpeechAnalyzer, which runs on your Mac. Our marginal cost per recording is zero, so yours can be too.
Is Thunder Kitty a good fit for teams?
Probably not, if you need team features. Thunder Kitty is a personal tool — there’s no shared dashboard, no team account, no automatic summary distribution to Slack or Notion. For an individual who wants a private record of their own meetings, it’s the right tool. For a team that wants shared meeting notes and integrations, tools like Granola, Fathom, or Fireflies are better suited.
Can I switch from a cloud tool to Thunder Kitty without losing my existing notes?
Your existing notes stay wherever they are — in Granola’s database, Otter’s system, wherever. Thunder Kitty starts fresh with local files. Download it, run a practice recording in Airplane Mode, and if it does what you need, start using it going forward. The transition is low-risk: you’re not migrating anything, just starting a parallel local archive.
Does Thunder Kitty have a free plan?
No — just a 7-day free trial. No credit card required, no account, just a download. If it works for you after a week of real use, subscribe. If it doesn’t, there’s nothing to cancel.
Fathom has a generous free plan. Why would I pay for Thunder Kitty?
Fathom’s free tier is genuinely good for video call summaries — it’s hard to argue with free. The core difference: Fathom processes your audio and generates summaries on its cloud servers. Thunder Kitty does both entirely on your Mac. If your meetings are routine work calls and cloud processing is fine, Fathom’s free tier is compelling. If the content of your meetings is sensitive enough that you’d rather it not exist on someone else’s server, Thunder Kitty is the right choice.
Does Fathom send audio to the cloud?
Yes. Fathom transcribes and summarizes on its servers. Thunder Kitty processes everything on your Mac — audio is never transmitted.
Is Fathom good for sensitive meetings — therapy, legal, board-level?
Fathom is excellent for sales calls, customer meetings, and team standups where cloud processing is acceptable. For meetings where data sovereignty is a hard requirement — therapy sessions, attorney-client conversations, executive discussions, investor calls — Thunder Kitty’s on-device architecture is the appropriate choice. Fathom wasn’t built for those use cases.
Does Fathom work outside of Zoom?
Fathom started as a Zoom-native tool and has expanded to other platforms, but it’s designed around integrating with video conferencing apps. Thunder Kitty captures any audio on your Mac regardless of application — including in-person meetings, phone calls, and anything else.
Can I switch from Fathom to Thunder Kitty?
Yes. Your Fathom history stays in Fathom’s system. Thunder Kitty starts fresh with local files. Download it, try it on a real meeting with Airplane Mode on, and if it works for you, start using it going forward. Nothing to migrate, nothing to cancel urgently.
The short version
Fathom is the best free tool for recording scheduled online meetings. If that's your use case, it's hard to beat.
Thunder Kitty is for everything else — and for people who want the record to live on their Mac, not someone else's server.
Try Thunder Kitty free for 7 days. No credit card. No account. Just a download.
Download for macOSIf you try it and Fathom is the better fit, use Fathom. We'd genuinely rather you use the right tool.