The idea behind a second brain is simple and appealing: a place outside your head that remembers everything, so you don't have to.
The failure mode is just as consistent. You set up an elaborate system of folders, links and tags, feel productive for a week, then stop feeding it. The system was beautiful. It was also work — and any system that depends on your discipline eventually loses to a busy Tuesday.
So the honest way to compare these isn't "which has the most features." It's what does this app cost me on the day I'm tired, because that's the day that decides whether you're still using it in six months.
Here's what I've actually run, what each is good at, and where each one lost me.
Obsidian
Local Markdown files, bidirectional links, an enormous plugin ecosystem, and a graph view people either love or find decorative. Your notes are plain files on your disk, which means no company can shut them down — a real advantage, and one that looks even better after the year Pocket had.
- Genuinely best at: thinking in public with yourself. Connecting ideas over years. Owning your data outright.
- Where it lost me: capture. Getting a screenshot from Instagram into Obsidian on a phone, mid-conversation, is several steps too many. I ended up with a beautiful vault of things I'd sat down to write, and nothing I'd caught in passing.
Notion
The most flexible of the lot, and the most seductive. Databases, views, templates, relations. You can genuinely build a workspace shaped exactly like your brain.
- Genuinely best at: structured collections. Anything with fields — reading lists, job applications, trips, a CRM for your own life.
- Where it lost me: the flexibility is the tax. Every save asks which database, which properties, which view. That's fine when you're at a desk and terrible when you're in a queue at a supermarket. Mobile has improved a lot; it's still not a two-second save.
Apple Notes
Wildly underrated. It's fast, it's free, it syncs, it handles scanned documents, and its search quietly reads text inside images. For a large number of people this is genuinely enough, and they'd be happier admitting it than shopping for a system.
- Genuinely best at: frictionless capture on iPhone. The share sheet is one tap and it never makes you decide anything.
- Where it lost me: I'm on Android. Also, at a few thousand notes it becomes a long flat list — capture is excellent, retrieval gets mushy.
Google Keep
The Android answer to Apple Notes. Instant, colour-coded, syncs everywhere, and the widget genuinely works. Zero ceremony.
- Genuinely best at: short-lived stuff. Shopping lists, a code someone read out to you, a reminder tied to a place.
- Where it lost me: it doesn't scale into an archive. Keep is a whiteboard, not a library, and it's honest about that.
Evernote
The original, and still functional. Strong web clipper, good OCR on scanned material, deep search operators. Its reputation took a beating over years of pricing and ownership changes, but the product still does the thing.
- Genuinely best at: documents. Receipts, contracts, scanned paper.
- Where it lost me: it feels like software from a previous era, and after watching Pocket close I'm warier of building a decade-long archive inside a company whose direction keeps changing.
Your camera roll (yes, really)
Most people's actual second brain is Google Photos or Apple Photos, holding four thousand screenshots. Both can search text inside images now, which is more than most people realise.
- Genuinely best at: capture. Nothing beats the two-button screenshot.
- Where it lost me: everything after capture. Photos apps are organised around when and where a picture was taken. Almost nothing you screenshot is findable by either.
The pattern underneath all of this
Every tool above sits somewhere on one line, and where it sits predicts whether you'll keep using it:
Note-first tools (Obsidian, Notion) assume you'll invest at save time and reward you with structure. Powerful, and quietly demanding — skip the upkeep for a few weeks and the graph rots.
Capture-first tools (Keep, Apple Notes, your camera roll) assume you're busy and forgetful. Saving is free; getting things back is your problem.
Almost everyone I know who "failed at building a second brain" picked a note-first tool while having a capture-first life.
What I built, and its limits
I got tired of that gap, which is why Reminari exists. It's capture-first — one tap from any app, no folder to choose — but it does the reading afterwards: text pulled out of screenshots on the device, a title and summary written for you, automatic grouping, and search that works on meaning rather than the words you happened to use.
It is not better than Obsidian at connected thinking, and it isn't trying to be. There's no plugin ecosystem, no databases, no graph. If you enjoy tending a knowledge system, use the tool built for that. Reminari is for the other case: you want the remembering without the upkeep.
How to choose in one question
Be honest about which sentence is more true of you.
"I enjoy building and pruning a system." → Obsidian if you want ownership and linking; Notion if you want structure and views. Both will reward the effort.
"I just want to save the thing and trust I'll find it." → Whatever asks the least at save time and the most of its own search. Apple Notes on iPhone, Keep for short-lived things, or something purpose-built for retrieval.
There's no winner here, only fit. Pick the one whose daily cost you're willing to pay, because that's the only thing that predicts whether you'll still be using it.
Frequently asked questions
What is the best second brain app for someone who won't maintain it?
Something capture-first, where saving takes one action and the app does the filing. Note-first tools like Obsidian and Notion are more powerful and will quietly punish neglect.
Is Obsidian or Notion better?
Different problems. Obsidian is better for linked thinking and owning your files; Notion is better for structured collections with fields and views. If you want neither, both are overkill.
Do I need a second brain app, or is a notes app enough?
For a lot of people Apple Notes or Google Keep is genuinely enough, and there's no prize for using something more complicated. You've outgrown them when you can no longer find things you know you saved.
Can a second brain app read the text inside screenshots?
Some can. Apple Notes, Google Photos and Evernote all index text in images to different degrees. The ones that do this on-device keep the picture from having to leave your phone to become findable.
What should I actually save in a second brain?
Anything you'd rather not hold in your head — articles, receipts, confirmations, quotes, recommendations, screenshots of useful details. Save freely and let the app organise. A second brain earns its keep on the small stuff you'd otherwise forget, not on the things you'd have remembered anyway.
I built Reminari because I kept screenshotting things I never found again. I write here about saving, forgetting, and the tools in between.
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