OpenKnowledge is an open source project that showed up on Show HN, pitching itself as an “AI-first” note-taking app that goes head-to-head with Obsidian and Notion.
Unlike the two market leaders, it builds AI directly into the data structure from day one, rather than bolting it on afterward as a plugin or add-on feature — the way Obsidian does through community plugins or Notion does through Notion AI.
What’s interesting is that it’s fully open source: anyone can self-host or modify the code themselves, unlike Notion, which has always been a closed box.
But let’s be honest — this is a Show HN post, meaning it’s still an early-stage project that just launched, with no long-term track record yet.
If you’re a tinkerer who likes trying new things, go for it. But if you need somewhere reliable to store important data long-term, it’s better to wait and see which direction the project takes first.
Unboxing OpenKnowledge — what it actually looks like
From the screenshots attached to the HN post, you can immediately see a layout that feels familiar to anyone who’s used Notion or Obsidian — a left sidebar holding the note structure, a main editor in the center, and a separate panel for AI, kept apart rather than crammed into the same space.
What’s notable is that the design treats AI as an “assistant beside the screen” rather than a hidden feature — you can invoke it anytime without leaving the page you’re writing on. If a graph view is available, it would help visualize connections between notes, similar to Obsidian.
Overall, the UI looks clean and function-first rather than flashy, which fits the open source character of prioritizing function over form.
The day your Obsidian folder becomes a markdown graveyard
Have you ever opened an Obsidian vault you’ve accumulated over years and felt discouraged? Thousands of note files, links tangled together in a mess, unable to find a note you know you wrote, forced to rely on search with wild guesses at keywords.
When you try to get AI to help organize it, you end up installing 2-3 separate plugins, each speaking a different language — one can summarize, another can auto-tag, but they don’t sync their understanding with each other. In the end, you’re still stuck organizing everything manually.
Notion has a different problem — all your data lives on their cloud. Try to migrate out and you’ll hit exports with broken formatting, forcing you to fix files one by one.
This is exactly the gap OpenKnowledge is trying to fill — AI embedded in the system from day one, not a plugin bolted on later, plus being fully open source so you retain full control over your own data.
Where OpenKnowledge stands in the PKM battlefield
Picture three camps: Obsidian is the local-first camp, files stored on your own machine, but AI depends on outside plugins. Notion is the all-in-one camp, feature-complete but tied to its own cloud. Logseq is the outliner camp, focused on block-based structured thinking.
OpenKnowledge chooses to stand in a specific middle ground — combining Obsidian’s local-first approach with AI-native design embedded from the start. It’s not a hybrid trying to be everything to everyone, but a specific bet that “your data + AI that understands that data” should belong to you alone.
As a Show HN project, this is the launch phase — momentum needs to be tracked on GitHub going forward. But the positioning is clear: it isn’t competing feature-for-feature with anyone in these three camps.
From “write, then search yourself” to “write, then let AI help you think further”
Honestly, the real difference lies in where the architecture starts, not in the feature list.
Obsidian/Notion were designed as note-taking tools first, with AI plugged in later through plugins or a separate API layer. Data and AI end up as two separate systems that have to be connected manually. OpenKnowledge, on the other hand, places AI in the same layer as the data from the start — so searching for and linking notes doesn’t need to rely on external plugins.
What’s interesting is the question of data ownership — when AI is embedded and the whole thing is open source, your data never has to leave a system you control, unlike the plugin model, which often sends data out to external AI providers.
| Factor | Obsidian/Notion + AI plugin | OpenKnowledge |
|---|---|---|
| How AI connects to data | Bolted on later via a separate plugin/API layer | Embedded in the architecture from the start |
| Note search/linking | Relies on add-on plugins | Works directly with AI within the system |
| Data ownership | Data may flow out to external AI providers | Open structure, fully self-controlled |
| Setup cost | Easy to start — ecosystem already mature | Still new — ecosystem readiness is a question mark |
Features that actually change how you take notes
AI-assisted linking suits writers with hundreds of scattered research notes — the system automatically links related topics so you don’t have to chase down tags yourself.
Semantic search answers the “I remember writing something about this somewhere” problem — searching by meaning instead of exact keywords.
Local-first storage appeals to small teams who don’t want to pay per-seat pricing like Notion — data lives on your own machine, not tied to a subscription.
Self-hosting answers the needs of developers worried about data privacy when notes pass through an AI cloud — you can run your own server and control every point your data flows through.
Overall, these features target people tired of vendor lock-in more than they aim to impress with a polished UI.
OpenKnowledge vs Obsidian vs Notion — which one should you pick
Short summary: if you want pure note-taking with a dense plugin ecosystem, Obsidian is still the best fit. If your team needs an all-in-one workspace, Notion is still more complete. But if you want built-in AI that’s open source and self-hostable, OpenKnowledge is the new option worth watching.
Where OpenKnowledge clearly differs is being “AI-first” at the core, not an add-on plugin bolted on later, and offering self-hosting — something neither Obsidian nor Notion fully supports.
| Factor | OpenKnowledge | Obsidian | Notion |
|---|---|---|---|
| Open source | Yes | No (core is closed) | No |
| Built-in AI | Yes, at the core | Requires add-on plugins | Yes (paid add-on) |
| Self-host | Fully supported | Not supported | Not supported |
| Plugin/Ecosystem | New, still small | Largest, most established | Focused on cloud integrations |
| Real-world readiness | Just launched on Show HN | Stable, battle-tested for years | Stable, battle-tested for years |
What it does well, and where it still stumbles
OpenKnowledge’s strength is open source transparency — the code is open for inspection, so you don’t have to worry about vendor lock-in the way you might with Notion or closed Obsidian plugins. Add to that the AI-first concept, designed to work with AI from the ground up rather than tacking on a feature later.
But being new comes with the usual growing pains — the plugin ecosystem is still thin compared to Obsidian’s years of accumulation, plus you need to bring your own AI provider API key, which means added cost and a more complex setup than just opening an app and using it right away. Documentation is also incomplete, so newcomers may have to figure a lot out on their own.
Pros
- +Open source and transparent — code can be audited, no vendor lock-in
- +AI-first concept designed to work with AI from the ground up
Cons
- −Still a new project — plugin ecosystem is thinner than competitors'
- −Requires your own AI API key, adding setup steps and cost
- −Documentation is incomplete — newcomers may have to figure things out themselves
The real cost of switching to OpenKnowledge from something else
The Show HN post doesn’t mention this, but it matters a lot: LLM API costs come out of your own pocket monthly, unlike Notion AI, which is bundled into the subscription price. The more you use it, the more you pay — no fixed price.
Migrating data from your existing Obsidian/Notion setup is also a cost you can’t ignore — you’ll need to convert formats and verify that old notes/databases transfer over intact.
Another risk is that this is a single-maintainer project that just launched. If maintenance stops partway through, any work tied to this tool gets stuck.
If you choose self-hosting instead of cloud, you’ll need your own server, adding another layer of system administration overhead. Budget for both the money and the time before committing to an actual migration.
Who it’s for, who it’s not for
Made for
- Developers already comfortable with self-hosting who want to try something new and tinker with an AI-first workflow
- People concerned about data privacy who don't want personal notes sitting on someone else's cloud
Think twice
- Teams with enough time to trial the system first, but who need a backup plan in case the maintainer disappears
Skip this one
- People not comfortable with technical setup — Notion or Obsidian, with their larger communities, will feel more reassuring
- Teams that need a stable tool they can rely on for real work today — this project just launched and still carries risk
When AI isn’t a bonus feature but a first-class citizen of the note-taking app
Obsidian and Notion were born in an era when AI was just an add-on plugin, tacked on afterward. OpenKnowledge instead rebuilt from the structural layer up, making AI part of the system from the very beginning — not a freebie thrown in.
If this trend continues, the two market leaders will eventually have to rethink their architecture entirely, not just add an “Ask AI” button to the existing UI — because users will start expecting AI that understands the context of their entire note collection, not just answers page by page.
What’s worth watching next is whether the maintainer can keep up a steady release cadence, and whether the community will grow large enough to build a plugin ecosystem that can compete with the incumbents. If it clears that bar, this could turn out to be a turning point for the entire PKM space.