Uploaded July 2026 | Updated September 2026, 2 weeks ago

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*Build Your AI Second Brain:* clickhubspot.com/r4mp
The smartest people in tech are racing to build AI second brains: personal operating systems that remember everything they know and get smarter every day. In this episode, Kieran shows you exactly what an AI second brain is, why it went from niche idea to the #1 trend in AI, and gives you a full demo of his own system so you can build one yourself.

After Andrej Karpathy's LLM wiki post hit over 20 million views on X, everyone from Brian Halligan (HubSpot co-founder) to Jason Lemkin (SaaStr) started building personal AI systems. Kieran breaks down why this decades-old idea finally works, what separates a real second brain from a folder full of notes, and the exact starter pack you need to build your own with Claude Code.

🎁 BUILD YOUR OWN: Take the transcript of this episode, drop it into Claude Code, and ask it to build your second brain starter plan. Kieran explains how at 17:20

Ep 436 Mentions
Andrej Karpathy ⁠karpathy.ai
LLM Wiki gist.github.com/karpathy/442a6bf555914893e9891c11519de94f
Obsidian ⁠https://obsidian.md
Tiago Forte ⁠youtube.com/@TiagoForte
Notion ⁠notion.com
Brian Halligan ⁠linkedin.com/in/brianhalligan
Claude ⁠claude.ai

📌 WHAT WE COVER:
→ What an AI second brain actually is (and what it isn't)
→ Andrej Karpathy's LLM wiki that started the craze
→ Brian Halligan's "Hal": an AI agent that runs his entire day
→ Tiago Forte's Second Brain, rebuilt for the AI era
→ Why Ray Dalio's decision journal was the original second brain
→ The maintenance problem that killed every note system before AI
→ Why a second brain compounds and makes you smarter over time
→ Storage and search vs real retrieval and evolution
→ Personal brain vs team brain vs company brain
→ Full demo: Kieran's personal operating system
→ How the LLM wiki captures concepts automatically
→ The ingest command that keeps everything current
→ The starter pack: vault, AI assistant, folders, routing logic
→ How to build yours today with Claude Code

🎙️ Host: Kieran Flanagan

⏱️ CHAPTERS:
00:00 — Intro: The #1 Trend in AI Right Now
00:20 — Karpathy's LLM Wiki (20M Views on X)
02:30 — Brian Halligan's "Hal": An Agent That Runs His Day
04:10 — Tiago Forte and the Original Second Brain
04:30 — Jason Lemkin's AI Version of Himself
05:20 — Why This Is Exploding Right Now
06:10 — Ray Dalio: The Pre-AI Second Brain
07:00 — What Changed: AI Killed the Maintenance Problem
07:50 — The Real Unlock: Intelligence That Compounds
08:50 — What No One Tells You (Storage vs Retrieval)
10:50 — Personal Brain vs Team Brain vs Company Brain
12:20 — DEMO: Inside Kieran's Personal Operating System
13:40 — Tracking Projects Across Every Team
14:10 — The LLM Wiki in Action
15:50 — Running Ingest: How It Stays Current
16:50 — Why Build This: Stop Starting From Scratch
17:10 — The Starter Pack: Vault, AI Assistant, Folders
18:20 — Routing Logic: What Your AI Should Look For
19:40 — Steal This Setup (Transcript + Claude Code)

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#AISecondBrain #SecondBrain #ClaudeCode #AIProductivity #PersonalKnowledgeManagement #AIAgents #AIAssistant #Karpathy #Obsidian #AIForMarketers #MarketingAgainstTheGrain #AITools2026 #PersonalOS #KnowledgeManagement

Host Links:
📲Kipp Bodnar, twitter.com/kippbodnar
📲Kieran Flanagan, twitter.com/searchbrat

‘Marketing Against The Grain’ is a HubSpot Original Podcast // Brought to you by The HubSpot Podcast Network // Produced by Darren Clarke.

About the Show
Kipp Bodnar, HubSpot’s CMO and Kieran Flanagan Hubspot's SVP of Marketing, lead you down the rabbit hole of marketing trends, growth tactics and innovation. On the way you’ll pick up undiscovered strategies to give you that slight edge for success. These are not your typical twitter thread regurgitated marketing tactics that everyone is doing. These are new methods, with unfiltered examination of successful fresh ideas.