Memory loss, forgetting something when you need it, or feeling that you are relearning something. You probably experience these frustrating sensations regularly in your life. In this article, I discuss the concept of building a second brain to help you cope with the challenges of long-term memory. Personal knowledge management (PKM) is a topic I am passionate about, so I hope that you will bear with me for a general and software-agnostic introduction.

Behind the idea of a second brain, my argument will be specifically focusing on storing information on the long term, for personal use (not restricted to your personal life though). Other uses, including organization wide and collaborative knowledge management, hold quite different challenges, which I am not going to cover in here.

My adventure with personal knowledge management begins in 2019, when I finally acknowledged that my organizational method was hopeless and got started searching for a solution. I had been inspired by my father, who has been using a tool appropriately called The Brain ever since the middle of the 2000’s. At home, I was repeatedly amazed by the effectiveness by which he could retrieve so many kinds of information from his computer-based knowledge base. However, at that time I had specific requirements that made me exclude The Brain, notably its pricing and the absence of a GNU/Linux compatible version. Ultimately, I started building my second brain in 2021 with TiddlyWiki, then switched to Obsidian two years later.

The motivation

Let’s acknowledge that the human brain is impressive and unique on earth, doted with yet unequalled intelligence, creativity and memory. However, it comes with a limited capacity, it is prone to mistakes and oversights. Building a second brain is the idea of storing and structuring information that you want to remember, and in particular to reuse, on an external medium. It complements your own brain by offering benefits such as quantity, clarity and longevity, thereby partially overcoming its limitations.

Having a second brain can help you be more efficient at manipulating knowledge, to better understand complex and large concepts, it can help to produce creative work like writing. In consequence, having a reliable support for storing information boosts learning. It becomes worth it to spend more time exploring because you are confident in that you will be able to retrieve the acquired knowledge fairly easily when needed.

From my experience, this has really pushed me to grasp new topics, including bigger ones. Notably, it made me feel ready about going for a PhD and doing research. Working together with my second brain was essential in practice thus far.

Traditional systems

Not everyone is familiar with the probably pretentious term of “second brain”, but that does not mean that people did not attempt to build one either. Among those past undertakings in history, I recommend reading this article about a machine called the “memex” by Vannevar Bush, first published in 1945. There is a Wikipedia page about the Zettelkasten method which was invented in the eighteenth century, the commonplace book and personal knowledge database pages are also very insightful to read as well. Yet, those advanced organizations systems are not what the people commonly implement.

Paper notebooks

The classic form of storage, and still very much often practiced, is the good old paper notebooks, which we have been trained to use since primary school.

While they have offered a decent medium for centuries, they are very constraining. Although they are relatively big physical size compared to digital devices, you cannot store that much information on it. They start accumulating, whether it is for saving lecture notes, writing minutes of meetings, or for creative thinking. Indeed, think of all the different notebooks that you have used during your education for the different years and subjects, while sometimes having several for each one of the latter. Consequently, searching for something in notebooks is not straightforward, you must remember the subject, year, page, and where the required notebook actually is. For practical reasons, knowledge workers cannot carry all of their notebooks everywhere they go. So they have to decide on the most relevant to bring, with the risk of being wrong and missing some information.

Another important consideration is that most of the additional pieces of knowledge acquired builds on top of previous grounds. Sometimes also, past erroneous or incomplete information should merely be updated than rewritten from scratch. Yet, with this medium, editing preexisting notes turns out overcomplicated and messy compared to starting over again on a new page. I should stress that this extra effort has at least one benefit, it can help to memorize. Unfortunately, I do not have the leisure to go through this process every single time I have to update information.

Finally, structuring knowledge on a per subject basis has limitations. Many concepts cross-cut disciplines and possible connections between them are harder to represent and exploit using physical notebooks.

Digital notebooks

Gone are the days when paper was ruling the world of information. Digital devices have replaced a large part of that in our personal and professional lives. Then, how do humans make use of this technology in respect to knowledge management? They use Word documents (or alternatives), Evernote or even simple text files. We have also seen more advanced tools popping up in work environments, like OneNote, Notion or other personal wikis. But they tend to be used as mere virtual replacement of notebooks, haunted with many similar limitations. Even modern applications like Notion and OneNote maintain a folder structure that replicates the archaic physical storage. We are offered to store notes in folders and subfolders (e.g., OneNote pages are stored in a specific section, itself located in a specific notebook). In general, even with a digital-based knowledge system, things can get lost. Information can be scattered in many locations on the device, on multiple local, external or cloud drives, not to forget several accounts and digital devices.

The single path access due to the structure of single file location organization system tends to add some overhead when saving new items. You have to think of where it should be best located, or rely on duplicates to have it in many places, with the problems that come with it.

I advocate to get away from those limitations and opt for a system based on connections. In fact, you should neither have to remember where each note that you need is located, nor its precise name.

How to use it

Capturing knowledge, and structuring it, is part of the thinking and learning process. Behind this concept is the idea of maintaining evergreen notes that are continuously reviewed and updated. Yet, we are more familiar with temporary notes, like those taken during a meeting, which are not meant to be updated and from which it is harder to build strong knowledge. We should see our notes as art, that starts as a vague idea, turns into a draft and gets gradually polished. I like how some people refer to this as “digital gardening”. 

The power of the digital format is that information can be virtually anywhere because backlinks are still easy to make. “Backlinks” correspond to bidirectional linking, where the connection is visible both in the referring note and the mentioned note. The latter is aware of all the other notes referring back to it (hence the term backlink), ideally with some context attached next to each backlink. They make it possible to create some virtual structure by parenting notes via linking to other content to which they are related. Those mentioned notes can thereby be used as entry points, listing related notes. This makes it possible to get to the same note from different paths, depending on the mental associations used, just like if it was stored in those many places while still being the same note. Also, links help to reduce the amount of information stored in a single note, while easily providing access to it, also avoiding duplicating information inside notes themselves. On Wikipedia or the web in general, hyperlinks make you aware of the additional available information, you can choose to explore it or not.

In contrast to some big voices among the second brain community, I do not try to maintain atomic notes, which favours notes being very specific. I want my notes to have the content that I find the most meaningful and avoid scattering things more than necessary. Whenever the note length gets impractical, both in terms of readability and reuse potential in other notes through links, I start considering breaking it down into smaller notes. In consequence, when the knowledge on a particular topic grows in your system, it becomes ideal to implement indexes, also called map of content. Those work by maintaining entry point notes for the large topics, those indexes give an overview of the different notes related to a particular topic. They can be structured and adjusted on the go, and also be automated by leveraging the backlink capabilities (i.e., listing notes mentioning a specific parenting note), some tools offer advanced querying systems to fine tune this listing of links. In my use case, I do not strictly separate index and notes, instead I tend to insert references to any other relevant files I may be looking for when reading the note, whether they are related topics or subtopics.

Navigating notes via links is only one way, the classic search function must not be neglected. In fact, this is still the approach I use the most to access my notes. That is not to say, however, that links are not relevant. They are critical for retrieving older notes when you do not remember the name, location or its existence, which is one of the main reasons to maintain a second brain. When it is possible, searching for notes via their name is like directly calling them. Nonetheless, giving a good name, that is easy to remember, short and clear is not straightforward, especially for new and complex topics. That is why having a way to give your notes as many names, or aliases, as you like is a must-have for any personal management tool. There can be several synonyms, you would rather not try one by one when looking for a note, not to forget about multilingual use and the different translations! Though, I do not give my notes all possible names, just the ones I use or see the most.

Having said all of that, sometimes I struggle to find information I know is stored in my vault. When I finally find it, I would learn from the experience by updating the note, giving it a better title, additional alias and improving its links so that next time this does not happen. Also, I am not against some structure, I even advise having at least three different folders: one where all stable information is stored, which eventually contains most of the notes and one that serves as an inbox, where all new notes automatically end up by default. This separates the process of recording and organizing, thereby relieving some pressure to focus on the note itself. This also helps when you are not sure whether you will keep the note, by separating it from the vast realm of already existing notes. Finally, I recommend having a temporary folder, where you can still explore some features and put short-lived notes (e.g., editing a duplicated note before export without altering the original version), basically serving as a sandbox. You could virtually delete the content of this folder at any time without dramatic consequences. Depending on if your tool such functionality natively, an additional fourth folder serving as an archive could be ideal. This is similar to the recycle bin we have on our computer, which can minimize the risk of unrecoverable mistakes induced by direct permanent deletion.

A record, if it is to be useful to science, must be continuously extended, it must be stored, and above all it must be consulted – Vannevar Bush

What should be stored

You want to store any information that is likely to be useful in the future, especially when it is more efficient to have it in your second brain than to spend time searching from external sources once again. This has to consider the time it requires to record, structure and later search for it from your system versus how long it takes for both searching and comprehending third-party information. Nevertheless, some information may be impossible to access by any other means than your second brain when you need it. This includes personal communications from people who are not reachable, explanations coming from books you do not have access to, or which are simply too massive to quickly skim through. Having saved the information is also critical when you are away from an internet connection or when you need very fast access to it. Knowledge acquired from your own understanding, based on inferences, is suitable and relevant example. My second brain often helps me in reexplaining difficult notions in a way that is much clearer and faster way than if I had to get through an external source again. It is not because I have understood or inferred something in the past that it is going to last forever, in such cases I have better securing it in my second brain. My personal reflections are another kind of knowledge, which could be simple annotated content that add extra meaning.

In general, when dealing with any interesting new information, I ask myself: “would the future me prefer finding this in the second brain, or searching for it again from external sources will be easier and faster?”

I would rather not waste time, effort and memory, so I naturally end up selecting, similarly to the brain filtering information. People cannot simply store anything they find, as this would take an infinite amount of time and storage resource. I think that whenever some information could potentially be helpful in several years, it makes sense to save it. You should also focus on the minimum yet meaningful fragments worth being stored. This means that you should avoid storing duplicated knowledge, making you lose time in saving, rereading and updating it. Distillation of this knowledge is the following step, you want to extract the smallest fraction of information that is relevant for you and to disregard the rest. Time does not allow us to reread entire books or any other references to get some information again. I generally do this refining iteratively: I first collect a reference (e.g., borrowing a book); while I process it I would annotate passages that seem interesting (e.g., highlighting a PDF, taking notes during a presentation); then I select what is worth keeping in respect to what I already have and what I need; finally when rereading those later in my knowledge base I would consider removing irrelevant details or in complementary ways to highlights key ideas within for future fast skim through. I would sometimes go one step further and add some short bullet points on top of the note to summarize the key ideas. This both helps me to put things into perspective and for future quick use of the knowledge. This process is called “progressive summarization”, an idea which is presented in Tiago Forte’s book “Building a second brain”.

With experience you get more sense of what is relevant, but this selection has to remain agile. I would sometimes not be able to properly judge about the future potential, so I just relax and allow myself to exceptionally save it anyway, it will remain possible to remove it during a future cleaning. Using an inbox folder limits the chances of flooding your knowledge base if those situations are frequent.

I also personally prefer to distinguish store short-lived information and long-term memory. The former can accumulate very fast, and I prefer not having many notes laying inside my second brain with quickly outdated information. Short-term includes live notes (e.g., meeting minutes), to-do lists, project management, etc. I am maybe overcautious on that, so do not take it rigorously!

A second brain complements your biological memory

You should not passively feed your second brain with content, but be thoughtful on building meaningful notes. Involving your own brain in the process indirectly trains it, just as we advise students to take notes to keep them active in the learning process. Copy-pasting what you read or ear is still quite passive. You should pre-digest information as much as possible. Make sure to understand it, highlight the core of the key information, while removing repetitive or uninteresting stuff.

Knowing about what you know is also crucial. Indeed, I frequently find myself facing challenges it seems I already faced in the past. I would quickly search my second brain and surprise myself with preexisting information which can help me. I want to emphasize that this meta knowledge is probably more important than remembering the actual content of the notes themselves when it comes to knowledge management. When the information is stored clearly, one just has to retrieve it and exploit it when needed.

Train your mind for natural recall in parallel, which is still necessary in situations where fast answers are needed (e.g., casual conversations, meetings, or when live understanding or explanations are expected). To improve it, there are some complementary methods, and I particularly like spaced repetition using flashcards. Your second brain would still contain more information in quantity and the less critically fast access knowledge. I recommend reading this nice comic strip to learn more about space repetition and how it helps in remembering things.

All in all, keep the right balance between biological memory and your second brain.

One cannot hope thus to equal the speed and flexibility with which the mind follows an associative trail, but it should be possible to beat the mind decisively in regard to the permanence and clarity of the items resurrected from storage. – Vannevar Bush

Practical considerations and cautions

As said earlier, saving information and structuring it in a second brain has to serve a purpose and be used ultimately. Otherwise, you are probably going to lose your time.

An important warning if you want to stay productive is to be careful not overengineering your system passed the point of diminishing returns. I have seen people expressing regrets regarding this. There is so much theory, workflow examples and powerful tools available that it can be a never-ending process to build your dream system. Although I think that a minimum exploration and training is indispensable, keep it limited and get started exploiting your system fast. You have to try, fail and discover what works best for you with experience. Then stick to it as much as possible to start drawing benefits, even if it feels incomplete on the edges, as perfection is the enemy of good. Having your most recent notes together will already be beneficial fast. For most of us, knowledge management remains a means to get the work done, not an end in itself.

My vision of a second brain encourages putting all pieces of my long-term knowledge at the same place. Yet, centralizing information increases the risk of losing it all if not properly managed. That is why I recommend implementing a backup process in parallel, look at implementing the 3-2-1 principle like IT engineers.

In my opinion, sharing your second brain as a whole with others is impractical, it should not primarily be aimed for. There is not yet a “one size fits all” software or method in my opinion, both personal and collective knowledge management have different use cases. Librarian and archivists have developed systematic classifications to allow their colleagues and libraries’ users to retrieve information on their own. But such a system has to be learned and followed strictly. It can be very frustrating when a certain item has been classified under a different category than the one you would have naturally thought of. What we are looking for when building such a personal knowledge base, is to be less constrained by a classification system ruled by conventions and take benefit from your personal association of thoughts. Yet, I manage to share notes occasionally by doing exports of single notes. But even this could be altered by the way you organize the content of the notes. What may speak to you may be unclear to someone else, and you do not necessarily want to overload your notes with additional information not useful to you. My advice is to first learn on your own, improve and when you are ready go out contributing in the outside world, all on top of the solid grounds built in your first and second brain.

One of my biggest, yet easy to achieve, advice when it comes to storing knowledge is to always give it some context and source. I am doing a PhD so it may sound specific to academics, though I realized the importance of doing it even before jumping in my research journey. In fact, I used to seldom mention the source of facts and store them as if it were the truth. With time, I started to look back at my older notes, I found myself uncomfortable with facts for which I could not judge the reliability or the origin. I would not even be able to differentiate from my words versus something copied from an external reference. Consequently, I strongly recommend always sourcing the information. Along with the origin, I save the year of publication for journal article and books or the access date for anything found on the web. This also holds for personal communications (e.g., a discussion with a colleague, an email). When it is some personal thought, I still date it and mention myself. This really helps the future me trying to figure out if the information can be considered still valid for the purpose of the use of it should be considered fragile or outdated.

The more you use a second brain, the most efficient it becomes. You train at finding what you need while you improve it when it fails to do it for next time.

Finally, maintaining it takes time. Just like you take care of your physical belongings, you should also do it for your digital garden. This means frequently reviewing parts of the second brain, split or merge notes, clean outdated content, add missing links, and get an overview of your available knowledge. This process helps in getting some hindsight about your meta knowledge, which I previously mentioned. It pays off without you realizing whenever you use it, but again keep it reasonable.

A few personal and professional examples

In order to clarify the abstract concepts introduced in this article, I wanted to provide some illustrative examples, so you get to see situations where my second brain is useful in my daily life. I sort of separated my personal and professional use cases, even though they can be strongly related.

Personal use cases

• Gift idea list. I feel terrible at having creative and good ideas for gifts, plus I am against consumerism. I want to offer useful things that people will have use of. To support this, I eventually started to plan surprises for my beloved ones by recording ideas whenever they appeared, not waiting to the last minute with nothing great coming up.
• Writing this article. I am passionate about the topic of knowledge management and I have read books, articles and watched videos about it. Many key ideas were recorded in my second brain that I eventually compiled in this article. For example, the quotes from Bush were taken from it.
• I write about the history of my relatives. There is a lot of emotional value in what my beloved ones tell me from their life experiences and stories. When they will no longer be part of this world, I would still be able to remember and get inspired from them. The idea of forgetting what they once told scares me. Similarly, I write down inspiring pieces of advice so that I can recall them in the future and reflect on them with my experiences.
• When I read an inspiring book, I would save short exerts that summarize the key ideas I want to remember. Otherwise, it would get blurry fast and may eventually be forgotten. I would rather not reread them but prefer exploring others for the sake of crossing point-of-views and growing my knowledge.
• I document what I learn from tutorials and experience regarding bike repairs. There are issues that are recurring, but not so often, though I often forget in the meantime. Moreover, I find that many tutorials are incomplete regarding the instructions they provide, so my notes mix the procedures to have a more complete and suited procedure that fits with the specifics of my bike.
• Cooking recipes are interesting as they are typically adaptations to my taste and habits. When following a recipe I discover alternatives by trial and error and document them, offering new reproducible steps or alternatives ingredients. Also, many come from oral communication. One example is for the couscous recipe of my grandma that she only knows on top of her head. She once gave a first version, and when asked again months later for verification, she added other details and forgot about others she previously told. Eventually, I was able to get the jigsaw puzzle complete. Another example to illustrate the use of links, recipes are sometimes split and some parts used in several preparations. For instance, the sourdough bread recipe links to the sourdough starter recipe, which is also the case in the brioche recipe (sweet bread), whereas the pizza recipe and olive bread (fougasse) links to the sourdough bread recipe as being mere adaptations.
• To give a final personal use case of my second brain, I try to be better aware of myself. My digital garden is a place where I reflect on my goals. I once also thought about my qualities and flaws, I listed them down with some example situations to help me think about them. I later realized that it was useful to track change when I reread them several months later.

Work related use cases

• At the crossroad of personal and academic knowledge lies my reading notes. When I read something interesting, whether it is a book, a scholarly article or any document, I save the interesting extracts in my second brain. If I was not doing this it would probably get forgotten quickly, even though these are digitally annotated, remembering the right references is not guaranteed among the hundreds of documents I check every year.
• My second brain serves a support for learning new scientific methods. For example, I have used it to learn input-output analysis and life cycle assessment, two large and important sets of methods related to my PhD research. Matured notes now help me a lot when I deal with one or the other to recall some aspects of the method.
• I also use it extensively to learn Python libraries and build my own documentation, one example is with the extensive “pandas” library. There are many cases where I found some approaches via web search, provided by StackOverflow answers or some random blog describing it, not to forget AI, but as a last resort (for sustainability and reference reasons). I saved any that worked and seemed to be possibly useful again in the future, while carefully documenting any additional information to make it clear for me, along with the source. Similarly, I used it to learn VBA several years ago, recently I wanted to use a script found on the internet, which led me to reuse older notes to help me understand and fix the script. Another frequent and similar use is to document complex Excel formulas that I do not want to learn by heart.
• Through my bibliographic work, I read some articles about biomass pretreatment a few months ago, some more than a year before. I had carefully saved the key information that about them. I reused the note recently, and it was more accessible to grasp than going through the publications again. Furthermore, I eventually got a new level of understanding by looking at my notes and trying to refactor the structure to make it more meaningful, realizing some discrepancies in the way some authors classified things in their article.
• I am writing my first research paper, and the content I saved in my second brain helps me a lot thanks to the references I read all along my PhD initial year which were organized in my second brain. Having bibliographic reference next to facts really helps.

Uncertainties and future perspectives

Even after several years of experience, I think I still have some uncertainties regarding my knowledge management workflow. I am sharing those along, for the sake of transparency, and to highlight once again that building and maintaining a second brain is an ongoing process.

I still have not got a proper archiving system to handle outdated, unused or simply content that is not useful after all. I tend to accumulate more than I think I will eventually need, which is not necessarily a bad thing. Occasionally, I would remove content, but only when I come across them. I should probably take the habit of doing recurring reviews (e.g., once a year, when having some free time), similarly to cleaning pictures on my phones or clearing my mailboxes. I have better doing on the go as much as possible can, the rest has to be taken care of during those clean-up sessions.

Another consideration is the use of artificial intelligence (e.g., LLMs) related to processing the knowledge in my second brain. This kind of applications started popping up quite fast in the past few years. The idea is the AI would be more efficient at summarizing your accumulated knowledge than you looking up for it, just like AI used to replace some browsing of the internet. It can potentially help you by discovering unthought connections in your knowledge. However, I did not implement AI for two reasons. The first is that some content in my second brain is private, I am not OK to blindly share my entire knowledge to big tech companies so easily. The other reason concerns the sustainability of AI and I would rather not generate yet another use of AI.

While the dream is to have all of what I need in the same place, making it searchable, I still separate concerns. I see my second brain as a place for long-term knowledge, and use other tools for things related to project management, personal to-do lists, official documents, photos, work files and library files (e.g., books and articles). This works fine for now, the categories are limited in number, but it could probably be improved and the file management done more systematically.

Finally, I would like to get some insights regarding my use of the second brain. Having some statistics on the content I use the most and the least, could help me see where is my most and least relevant use of my second brain. It is something I should invest some time in when I will be less busy.

Despite those limitations, I do not look hard to come up with a solution. If they become important in the future, I might consider exploring those. I do not want to possibly waste time looking for a solution that is just waiting for a problem.

A final encouragement

As we reach the end of this article, I hope that you have learned something and that it sparked your interest in building your second brain.

If you work in academia, are a student or just enjoy learning, I think that building a second brain will suit you well. This is the type of tool you probably need to cope with large quantity of information to grasp.

Keep in mind that your system will always be imperfect and evolving. You should not wait until you find the ultimate tool and method that fits perfectly with your ideal system. Just get started with one that checks your minimum requirements. The rewards come with time, throughout the experience you will gain and based on the accumulation of interconnected relevant knowledge. I find it so satisfying to read notes from several years ago being useful, and reminds me of the power of maintaining a second brain.

Keep in mind that a second brain is not just about having a knowledge management tool, it is primarily a mindset: You want to organize information in such a way that you make it easy to retrieve and reuse in the future, the tool has to serve that purpose. In essence, your second brain as a gift to the future you.

Now if you are eager to know more about my experience with using Obsidian to build my second brain, I invite you to proceed with the next article.

Appendix: Short overview of apps available

Getting towards practice after theory, I want to share some apps that can be interesting to explore. This is not an extensive overview but my two cents about different software, what they have to offer and their limitations in my opinion.

• Obsidian.
  • This is my second brain app where I store and organize my medium to long-term knowledge. I trust it as it works offline by design, based on markdown files which have excellent interoperability. I love its deep customization capabilities and its backlink functionality built into it. Finally, it is compatible with most operating system, considering that I use a lot the mobile version and had to use it on all the supported OS. Note that it does not offer file synchronization out of the box. You can read more about it in the article I wrote specifically about my experience with Obsidian over here #todo.
• Logseq
  • I did not use it, but I know a bit about it. It is a good and powerful alternative to Obsidian. It is amusing that they were both initially released in 2020 and are very similar. Although it has much fewer plugins to offer at the time of writing, it has a growing community, which I find important for getting help, inspiration and new features. It also works offline first, with a highly customizable interface. Contrary to Obsidian, it is open-source software. It has a mobile application, but it is more limited than the desktop version.
• Roam
  • I did not use it. It has probably influenced Obsidian and Logseq, as it looks very similar. A big difference is that it is a web-based application (Software-as-a-Service, SaaS) and I do not trust this model on the long term because the company has to maintain for the service to work. This is a subscription-based system with no free plan, and I find it not cheap. Finally, I am not sure about its long-term perspectives and strength to keep up with the competition.
• Notion
  • I am using it for my short-term second brain since several years and I organize my work-related projects, temporary notes and tasks inside. It is not so new any more but managed to keep up with the competition. They really brought a positive change to the world of productivity apps with a well-designed (UI) and awesome user experience (UX). It is a web-based application, with free and paid plan (note that I get the paid plan for free as a PhD). It has remained quite healthy economically speaking, but I would still not trust a SaaS for a long term second brain. Notion has only limited support for backlinks, although I think this will improve in the future.
• OneNote
  • A big player, extensively used among companies and in academia. However, to me, it is more of a digital notebook than a good knowledge or productivity app in my opinion. It is ideal for short-lived knowledge and has neat features for creativity.
• Personal wikis: MediaWiki, XWiki, TiddlyWiki and many more.
  • You can set up your personal wikis as a personal knowledge management system. There are commercial options such as Atlassian Confluence, which I tried before in a big IT company, I really liked the powerful full-text search.
• The Brain
  • This one is a special kind, which inspired me in building a second brain, following the experience of my father who had been using it for almost two decades as of the time of writing. This is an old, but still quite niche software. Although it is a seriously compelling option for building a second brain, also offering offline mode by design, its expensive subscription model did not fit with my needs.

There are many other apps around that I am not even going to mention, many that I am probably not event aware of. Please feel free to share if you know or use any that are good to add in the list!

Note on Software as a service (SaaS)

Today, many apps work on a Software-as-a-service (SaaS) model, meaning that even a part or the entire interface is delivered via internet and not installed on your local computer or phone. When I started considering building my second brain, I did not have mobile internet because I was living in a place where it was costly and limited. Despite that today I have a decent internet connection, it is not always available. However, the worst concern arises when it is the SaaS software provider itself who fails. Outages happens, small to big tech companies are subject to it and this can go as far as loss of data. I want to avoid the pain of not having my data when I need it. It sounds weird to me that it requires an internet connection to access my knowledge, like if my brain was not located in my body.