Top 18 'Second-Brain-Building' AI Tools to install for turning digital clutter into a knowledge asset this year. - Goh Ling Yong
Are you drowning in a sea of browser tabs, saved articles you’ll “read later,” and scattered notes across a dozen different apps? You're not alone. We live in an age of information overload, where the constant stream of content feels more like a firehose than a fountain of knowledge. The challenge isn't accessing information anymore; it's capturing, organizing, and connecting it in a way that serves you.
This is where the concept of a "Second Brain" comes in. Popularized by Tiago Forte, it’s not just about digital storage; it’s about building an external, digital system for your knowledge. It’s a trusted place to offload your thoughts, ideas, and learnings, allowing your biological brain to do what it does best: think, create, and solve problems. But building this system has traditionally been a manual, often tedious, process. Until now.
Artificial intelligence is revolutionizing personal knowledge management. The new wave of AI-powered tools acts as an intelligent layer on top of your notes, transforming your static digital filing cabinet into a dynamic, interactive knowledge partner. These tools can summarize, connect, transcribe, and even help you generate new ideas from the information you've already saved. Here on the Goh Ling Yong blog, we're diving deep into the 18 best AI tools that can help you build a smarter, more effective second brain this year.
1. Notion AI
Notion has long been the darling of the all-in-one workspace community, a flexible canvas for everything from project management to personal journaling. With the integration of Notion AI, it has transformed from a powerful container into an intelligent collaborator that lives right inside your existing notes and databases. This isn't a separate app; it's a feature that enhances the work you're already doing.
The AI's power lies in its contextual awareness. Highlight a block of messy meeting notes, and you can ask Notion AI to summarize it, pull out action items, or even translate it into a different language. If you're staring at a blank page, you can use it to draft an outline for a blog post, brainstorm ideas for a marketing campaign, or write a first pass of an email. It understands the structure of your databases, allowing you to automatically fill properties or generate content based on other entries.
- Pro Tip: Create a "Reading List" database in Notion. When you finish an article, use the Notion Web Clipper to save it. Then, select the content and ask Notion AI to "Create a 5-bullet point summary" and "List the key takeaways." You'll have a digestible summary of every article you read, ready to be linked to other ideas.
2. Obsidian (with AI Plugins)
For those who value local-first data ownership and deep, networked thought, Obsidian is king. It's a Markdown-based note-taking app that visualizes the connections between your ideas as a beautiful knowledge graph. While Obsidian doesn't have a native AI, its vibrant plugin community has integrated powerful AI capabilities directly into its workflow.
Plugins like "Smart Connections" or "Text Generator" allow you to tap into models like GPT-4 or local LLMs right from your notes. You can select a piece of text and ask an AI to elaborate on it, find related notes you've written in the past, or even chat with your entire vault of knowledge. This turns your personal notes into a unique dataset that an AI can help you explore, revealing connections you might have missed.
- Pro Tip: Install the "Smart Connections" plugin. When you're working on a new note, open the plugin's sidebar. It will automatically scan your vault and display a list of your other notes that are most relevant to what you're currently writing. It's like having a research assistant who has read everything you've ever written.
3. Mem
Mem was one of the first apps built from the ground up with AI at its core, billing itself as "the self-organizing workspace." Its goal is to eliminate the friction of manual tagging and folder creation. You simply capture notes, and Mem's AI automatically finds the connections and resurfaces relevant information when you need it, a feature they call Mem X.
The real magic is in its "Similar Mems" feature, which automatically shows you related notes in a sidebar as you write. This fosters serendipitous discovery, helping you bridge ideas from different domains of your life. You can also chat with your knowledge base, asking questions like, "What did I learn about project management last month?" or "Summarize my notes on stoicism." It's a proactive approach to knowledge management that feels like your second brain is actively working for you.
- Pro Tip: Forward important emails, save tweets, and import notes into Mem without worrying about organization. A week later, start a new note on a related topic. Watch as Mem X automatically surfaces those disparate pieces of information, creating a cohesive picture you didn't have to build yourself.
4. Readwise Reader
If your second brain is going to be a knowledge asset, you need a robust system for getting high-quality information into it. Readwise Reader is arguably the best-in-class tool for this. It's a "read-it-later" app that lets you save articles, newsletters, PDFs, and even YouTube videos into one unified library.
Its AI feature, "Ghostreader," is a game-changer for consumption. You can ask it to summarize a long article before you commit to reading it, define a specific term within the text, or simplify complex paragraphs. For YouTube videos, it can pull the full transcript and allow you to ask questions about the content. All your highlights from Reader then sync to your primary note-taking app (like Notion or Obsidian) via the core Readwise service, creating a seamless pipeline from consumption to creation.
- Pro Tip: Use the "document Q&A" feature on dense academic papers or reports. Instead of reading the entire 50-page PDF, you can upload it to Reader and ask specific questions like, "What was the study's primary conclusion?" or "What methodology did the researchers use?"
5. Perplexity AI
Google is for searching; Perplexity AI is for answering. This conversational AI search engine is an indispensable tool for the research phase of building your second brain. Instead of giving you a list of blue links to sift through, it reads the top results for you and synthesizes a direct answer, complete with numbered citations pointing to the original sources.
This completely changes the dynamic of research. You can ask follow-up questions, request information in a specific format (like a table or a bulleted list), and dive deeper into any of the sources it provides. The "Focus" feature lets you narrow your search to specific domains like academic papers, YouTube, or Reddit, giving you more targeted results. It’s like having a junior research assistant who can do the initial legwork for you.
- Pro Tip: After Perplexity gives you an answer, copy and paste the synthesized summary and the list of sources directly into your second brain as a "Research Brief" note. This creates a pre-packaged, well-sourced starting point for any new project or area of interest.
6. Otter.ai
Some of our most valuable insights come from conversations—meetings, interviews, lectures, or even just voice memos to ourselves. Otter.ai is an AI-powered transcription service that captures this spoken knowledge and makes it searchable and useful. It transcribes audio in real-time, identifying different speakers and creating a fully interactive transcript.
The "AI Chat" feature is where it becomes a true second-brain tool. You can ask questions directly to the transcript, such as, "What were the key decisions made in this meeting?" or "What did Sarah say about the Q4 budget?" It will instantly find the relevant sections and provide a summary. This saves hours of re-listening and turns your conversations into structured, queryable data.
- Pro Tip: Connect your calendar to Otter.ai and set it to automatically join and record your Zoom or Google Meet calls. After the meeting, Otter will email you a summary with key takeaways and action items. You can then forward this summary directly to your knowledge base.
7. MyMind
If you're a visual thinker who finds traditional note-taking apps too rigid, MyMind might be for you. It bills itself as an "extension of your mind," a private, AI-powered space to save anything and everything that inspires you—images, links, notes, products, quotes—without ever having to think about folders or tags.
Its AI does all the heavy lifting. When you save an image, it automatically identifies objects, colors, and even text within the picture. When you save an article, it pulls out key topics. This allows you to search your mind using natural language. You can search for "blue logos," "quotes about courage," or "articles about productivity I saved last winter." It’s a beautifully simple interface for rediscovering the things you've found meaningful.
- Pro Tip: Use MyMind as your primary "inspiration catcher." As you browse the web, use the browser extension to toss in anything that catches your eye. Don't organize it. A month later, search for a broad term like "minimalist design" and be amazed at the personal mood board the AI has implicitly created for you.
8. Heptabase
Designed for deep, complex research projects, Heptabase is a visual personal knowledge management system that helps you deconstruct and understand intricate topics. It combines a whiteboard, a note-taking app, and a PDF annotator into one powerful environment. You can lay out all your research materials visually and draw connections between them.
The AI integration in Heptabase is subtle but powerful. It helps you find related notes and can summarize long documents or selected text, which is crucial when you're dealing with dozens of academic papers. The real value is in how it supports the human thought process of sense-making, allowing you to build visual mind maps of your understanding before you begin the writing process.
- Pro Tip: When starting a new research project, create a whiteboard in Heptabase. Drag all your source PDFs onto it. As you read and highlight, create new note cards with your own insights. Use the AI to summarize key sections and then visually link your insight cards to the evidence in the source documents.
9. AudioPen
Ever had a brilliant idea while driving or on a walk, only to forget it by the time you could write it down? AudioPen solves this problem with elegant simplicity. It's a web app that lets you record rambling voice notes, and its AI cleans them up, removes filler words, and transforms them into clear, well-structured text.
It's surprisingly effective at capturing the essence of your thoughts, even when you're not speaking coherently. You can choose different rewriting styles, from a concise summary to a more formal email draft or a casual social media post. This is the ultimate tool for frictionless capture, ensuring no idea gets lost because you couldn't get to a keyboard.
- Pro Tip: Add the AudioPen website as a shortcut on your phone's home screen. The next time you have a thought, just tap, record, and talk. Later, you can copy the polished text directly into your main second-brain app.
10. ChatGPT / Claude
It would be impossible to create this list without mentioning the titans of generative AI. While ChatGPT and Claude aren't dedicated second-brain apps, they are incredibly powerful processors for the information within your second brain. They are the engine you can use to work with the raw material you've collected.
Think of them as "thought partners." You can paste in a collection of messy highlights from an article and ask, "What are the underlying principles here? Generate three novel questions based on this text." You can feed it two seemingly unrelated notes and ask it to "Find a surprising connection or synthesis between these two ideas." This is where you move from knowledge management to knowledge creation.
- Pro Tip: Keep a "ChatGPT Prompts" note in your second brain. For example, create a prompt like: "You are a synthesis expert. Below are my notes on [Topic X]. Please review them and provide: 1) A one-paragraph executive summary, 2) The three most important takeaways, and 3) A potential counter-argument I should consider. [Paste notes here]."
11. Matter
Another strong contender in the "read-it-later" space, Matter offers a beautifully designed reading experience with powerful AI features. It syncs with your newsletters and lets you discover new writers through its recommendation engine. Like Readwise Reader, it's a fantastic input source for your second brain.
Its AI co-pilot can summarize articles, but it also has a unique feature that generates "AI Lenses," which reframe the article from different perspectives (e.g., "Critique," "Actionable Advice," "Devil's Advocate"). This encourages deeper, more critical thinking about the content you consume, rather than just passively accepting it.
- Pro Tip: Before saving your highlights from Matter to your main notes app, use the "Critique" AI Lens. Add the AI's critique to your notes alongside your own highlights. This builds a more robust, less biased understanding of the topic from the very beginning.
12. Consensus
For anyone whose work relies on scientific evidence, Consensus is a revolutionary AI search engine. Instead of searching keywords, you ask it a direct question (e.g., "Does intermittent fasting improve cognitive function?"). It then scans millions of peer-reviewed scientific papers and uses AI to extract the key findings related to your question.
The results are presented as a series of direct quotes from the papers, often with a "Consensus Meter" that gives you a high-level summary of whether the evidence is supportive, conflicting, or inconclusive. It's an incredible tool for cutting through the noise and getting straight to the primary research, a cornerstone of a well-founded second brain.
- Pro Tip: Use Consensus to validate claims you read in pop-science articles or books. If an author makes a bold scientific claim, frame it as a question in Consensus to see what the actual research literature says. Add the findings to your notes to create a more evidence-based knowledge asset.
13. Miro AI
Brainstorming and visual thinking are essential parts of knowledge work. Miro is a leading online collaborative whiteboard, and its AI features, Miro AI, supercharge the brainstorming process. You can use it to instantly generate mind maps from a single keyword, populate a board with sticky notes based on a theme, or summarize a messy collection of ideas into a clear, structured format.
This is fantastic for both solo ideation and team collaboration. It helps overcome "blank canvas" syndrome and can organize the chaotic output of a brainstorming session into actionable categories like SWOT analyses or user personas with a single click.
- Pro Tip: During a brainstorming session, encourage everyone to add their raw ideas as sticky notes. Once you have a critical mass, select all the stickies and use Miro AI's "Cluster Stickies" feature. It will automatically group related ideas, saving you a massive amount of manual sorting time.
14. Elicit
Similar to Consensus, Elicit is another AI research assistant designed for sifting through academic literature, but with a different workflow. It's particularly good at finding relevant papers and extracting key information in a structured way. You can ask a research question, and Elicit will not only find relevant papers but also create a summary table of their findings.
You can customize the columns in this table to extract specific information from each paper, such as the "Main Findings," "Population Studied," or "Limitations." This is an incredibly efficient way to conduct literature reviews and build a structured overview of the current state of research on a topic for your second brain.
- Pro Tip: After generating a table of papers in Elicit, export it as a CSV file. You can then import this file into Notion or another database-driven app to create a pre-populated, sortable, and searchable database of all the key research on a topic.
15. Logseq
For those who love outliners and open-source software, Logseq is a powerful alternative to Obsidian. It focuses on structuring your thoughts in daily journal entries and connecting ideas using bi-directional links. Its block-based structure makes it incredibly fluid for organizing and remixing thoughts.
The AI integration in Logseq comes through plugins, similar to Obsidian. You can install extensions that allow you to select any block of text and use an AI to summarize, expand, or ask questions about it. The AI can also help you generate content within the outliner structure, making it a great co-creator for drafting articles or study notes.
- Pro Tip: Use the daily notes page in Logseq as your primary capture location. At the end of the day, use an AI plugin to review your notes and ask it to "identify the main themes and suggest 3-5 relevant tags." This helps ensure your daily thoughts get properly integrated into your wider knowledge graph.
16. Napkin
Napkin is a fascinating tool focused on one thing: sparking new ideas by showing you surprising connections. You collect short notes or "thoughts," and Napkin's AI-driven interface displays them in a fluid, visual way, surfacing related ideas as you browse. It’s designed to combat the rigid, folder-based thinking that can stifle creativity.
There's no complex organization required. You just feed it ideas, and the app takes care of making the connections. It's a fantastic tool for creative professionals, writers, and anyone who wants to cultivate more serendipity in their thinking process. It's less of a comprehensive second brain and more of a dedicated "idea incubator."
- Pro Tip: Whenever you read a quote or have a fleeting insight that resonates with you, add it to Napkin. Don't worry about where it fits. Over time, browse through your collection and pay attention to the unexpected connections the AI reveals. Use these connections as prompts for your next journal entry or creative project.
17. Lex
If a significant part of your second brain's output is writing, Lex is a must-try. It's a clean, minimalist word processor with a powerful, always-on AI assistant. Unlike other tools where you have to highlight text or open a special menu, Lex's AI is invoked with a simple command (+++).
You can ask it to generate a title, suggest the next sentence, offer a counter-argument, or even critique your paragraph for clarity. It feels less like a command-line tool and more like a true writing partner sitting next to you, ready to help whenever you get stuck. I've found that, much like Goh Ling Yong often emphasizes about leveraging technology, the right interface can make all the difference, and Lex nails it for writers.
- Pro Tip: When you're stuck in your writing, type
+++and ask a question like, "Suggest a better way to phrase the last sentence" or "Give me an analogy to explain this concept." This is a great way to overcome writer's block and improve the quality of your prose.
18. Omnivore
As a free and open-source alternative to Readwise Reader and Matter, Omnivore is an excellent choice for building the "input" layer of your second brain. It's a read-it-later app that saves articles, newsletters, and documents, stripping away ads and formatting for a clean reading experience.
While its native AI features are still developing, its powerful integration capabilities are key. You can use its webhooks and API to connect it to services like a self-hosted LLM or other AI tools, giving you complete control over how your reading material is processed. For the privacy-conscious and technically-inclined, Omnivore offers an unparalleled level of flexibility.
- Pro Tip: Set up Omnivore to automatically sync your highlights and notes to Obsidian or Logseq. This creates a powerful, free, and open-source pipeline for getting information from the web into your local-first second brain, where you can then use AI plugins to process it further.
From Clutter to Clarity
The promise of a second brain is not just to remember more, but to think better. It's about creating a virtuous cycle: you capture interesting ideas, connect them to what you already know, and use those connections to generate novel insights and creative work.
For years, this process has been largely manual. But as we've seen, AI is the catalyst that transforms this system from a passive archive into an active intellectual partner. These tools aren't here to replace your thinking; they're here to augment and accelerate it. They handle the tedious work of summarizing, transcribing, and organizing, freeing you up to focus on the deeply human work of questioning, creating, and innovating.
The key is not to adopt all 18 of these tools at once. Instead, identify the biggest point of friction in your current workflow. Is it capturing ideas? Is it processing what you read? Or is it synthesizing your notes into new content? Start by trying one or two tools that solve your most pressing problem. Build a system, not just a collection of apps.
What's your go-to AI tool for your second brain? Did I miss any game-changers on this list? Share your personal stack and experiences in the comments below
About the Author
Goh Ling Yong is a content creator and digital strategist sharing insights across various topics. Connect and follow for more content:
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