simstim

Your calls. Your files. Your AI.

Simstim records calls on your Mac, transcribes them on the same Mac and saves each one as a Markdown file you own. Audio never leaves your computer.

Download for macOS

Version 0.12.0 · 16 MB · macOS 14.2 or later on Apple Silicon
Free, MIT license. Windows and Linux coming soon.

The Simstim window. On the left, a list of recent calls grouped by day. On the right, the summary of a design review: a short paragraph, a list of decisions, next steps with owners and one open question.

How it works

  1. Record

    Press Record. Simstim captures your microphone and the other side of the call as two separate channels. It can suggest recording when it notices a call, but it never starts on its own. Let the other people know before you record.

  2. Transcribe on your Mac

    A live transcript appears while you talk. After you stop, a second pass with a larger model improves accuracy. Both models run locally. You can take notes during the call, and they stay in their own section.

  3. Keep plain files

    Each call becomes a Markdown file with the recording beside it, in a folder you choose. Search across past calls, click a timestamp to hear that moment, or continue a recording into the same note later.

Files are the database

There is no export step because there is nothing to export from. Open the folder in Obsidian, keep it in git, sync it with the service you already use. Every other tool on your Mac can read these files today and in twenty years.

Your notes, the summary and the transcript live in separate sections. Re-transcribing a call replaces only the transcript, never what you wrote. 

Your notes/
├── 2026-09-09 15-30-00 call.md
├── 2026-09-09 15-30-00 call.m4a
└── 2026-09-09 11-00-00 call.md
2026-09-09 10-00-00 call.md
---
date: 2026-09-09T10:00:00+02:00
title: Beta planning
duration: 12m
people: Alex, Sam
---

## Notes

Keep the first release focused on recording and readable files.

## Summary

### Decisions

- Start with five testers using different Apple Silicon Macs.
- Keep PDF creation and sharing in the AI tools people already use.

### Next steps

- Sam: prepare a short sample call for the testers.
- Alex: send the installation checklist after the candidate passes review.

## Transcript

[00:00:04] Me: Let's start with five testers on different Macs.
[00:00:09] Them: I'll prepare a short sample call for them.
[00:00:24] Them: Should we add a PDF export before the beta?
[00:00:30] Me: The note is already a file. People can give it to the AI tools they use.

Optional AI. Yours, not ours.

Connect Claude or ChatGPT to get a summary after each call and to ask questions across your notes. Simstim installs the official helper and opens the provider's own sign-in. If you prefer, use your own OpenAI, Anthropic or OpenRouter API key, stored in macOS Keychain.

Simstim sells no credits and adds no fee. Your plan, your limits, your bill.

  • Text only. Summaries and questions send the note's text to your provider, never audio.
  • Off means off. Without AI, recording, transcription, notes, playback and search keep working.
  • Nothing to rebuild. For a PDF, a deck or a follow-up email, hand the file to your assistant. It already has those tools.

Plain answers

Privacy

  • No Simstim account, no hosted notes, no analytics.
  • Audio is recorded and transcribed on your Mac and stays there.
  • Network use is model downloads, the optional AI setup and the AI requests you make.
  • Deleting a note moves it to the Trash. Removing the app leaves your notes alone.

Limitations

  • Apple Silicon Macs on macOS 14.2 or later today. Windows and Linux versions are coming soon.
  • "Me" and "Them" are your microphone and system audio, not individual speakers.
  • Names and numbers can be misheard. Check important details against the recording.
  • Updates are manual: download a new version and replace the app.

The details are in the privacy document.

Download Simstim 0.12.0

Released . Signed with a Developer ID and notarized by Apple, so macOS opens it without workarounds.

Download for macOS

Simstim_0.12.0_aarch64.dmg · 16 MB

  1. Open the disk image and drag Simstim into Applications.
  2. Choose a folder for your notes and allow microphone and system audio. Speech models, about 1.55 GB, download on first launch.
  3. Connect an AI assistant if you want summaries, or skip it. Then press Record.
Verify the download

In Terminal, compare the checksum with the one published in the release:

shasum -a 256 ~/Downloads/Simstim_0.12.0_aarch64.dmg
2f75ab2acf5007700f8f9819e8d49f72b87f957a3b2b5375fdb7db7b2b344949

Release notes · All versions · Build from source

Updating from an earlier version: quit Simstim and replace the app. Your notes, models and settings stay where they are.