The Free, Self-Hosted Alternative to Notion, Roam, and Obsidian

If you like what Notion, Roam, and Obsidian do but you don't like paying a monthly subscription — or handing your notes to someone else's cloud — SiYuan is the free, self-hosted personal knowledge management app that gives you the same core experience without any of that.

You get block-level references, two-way links, database views, spaced-repetition flashcards, and built-in AI Q&A. It runs on Windows, Mac, Linux, Android, iOS, HarmonyOS, and via Docker. It's been actively maintained for six years and the whole thing is open-source under AGPL v3.

(SiYuan is a full standalone app — you can use every feature except the optional AI Q&A without any AI assistant at all. It's not a plugin for Claude Code or Cowork; it's the note-taking app itself.)

At a glance

What it actually is

A personal knowledge management app built on the same "block-based, bidirectional linking" foundation as Roam and Notion. You write in Markdown (with a live, formatted preview), each paragraph is its own referenceable block, and any block can be linked, embedded, or queried from anywhere else. That's the pattern that made Roam famous in 2019 and Notion the corporate standard by 2022.

The difference is where your notes live. Notion keeps them in Notion's cloud. Roam keeps them in Roam's cloud. SiYuan keeps them on your device — or on your own server if you deploy it via Docker. There's an optional cloud sync service the maintainers sell for a small fee, but you don't have to use it, and if you don't, your data literally never leaves your machine.

On top of the note layer, SiYuan ships things Notion charges for and Obsidian doesn't have out of the box: database views, spaced-repetition flashcards (Anki-style, built in), PDF annotation, web clipping via a Chrome extension, and AI writing + Q&A that plugs into your OpenAI or Claude account (you provide the key, you pay for the tokens).

What you get

• Block-level references and two-way links — the Roam/Obsidian core pattern, every block gets a stable ID you can reference or embed from anywhere
• Markdown WYSIWYG editor — you write in Markdown but see the formatted output live; no mode-switching
• Database views — sortable, filterable table views over your notes (this is the Notion core feature)
• Spaced-repetition flashcards — built-in review system that resurfaces cards at increasing intervals until you know them (the same model Anki popularized), powered by the project's Riff engine
• Live queries inside notes — you can drop a query (using SQL, the standard database language) into any note and it renders as a live table of matching blocks that updates as you add content
• PDF annotation — highlight and comment on PDFs, and every highlight becomes a referenceable block
• Web clipping — Chrome/Edge extension that pulls articles into your vault as clean Markdown
• AI writing and Q&A — built into the editor, uses your own OpenAI or Claude API key (so the cost stays with you and no third party sees your notes)
• Mobile apps that actually exist — Android, iOS, and HarmonyOS, all real native apps, not just web wrappers
• Docker deployment — one-command self-host for teams or personal use
• Community plugin marketplace — third-party plugins and themes, installable from inside the app
• Multi-language support — English, Chinese, Japanese, Turkish; app UI and documentation are fully translated

Why this matters for the privacy-conscious knowledge worker

Three things distinguish SiYuan from the three products most people would compare it to.

First, you keep your data. Notion, Roam, and Craft all put your notes on their servers by design. If they change their pricing, close down, or get acquired, your notes are subject to whatever the new terms are. SiYuan stores everything locally by default — the only way your notes leave your machine is if you explicitly opt into the paid sync service. For anyone in law, medicine, finance, defense, or any regulated industry, this is not a preference — it's a compliance requirement.

Second, there's no subscription. Notion is $10-15 per user per month. Roam is $15-30 per month. Obsidian is free personally but $50/user/year for commercial use. SiYuan is free for the app itself, forever, including commercial use, and the paid tier only kicks in if you want their optional cloud sync or a few advanced features — most people never need it.

Third, the mobile parity is real. This is where most self-hosted PKM tools (personal knowledge management apps — the category Notion, Roam, and Obsidian all sit in) break down. Logseq's mobile apps have historically lagged. Obsidian mobile requires a paid sync add-on or third-party workarounds. SiYuan ships first-class native apps on Android, iOS, and HarmonyOS, from the same codebase, all synced through whatever mechanism you choose. If you take notes on your phone or read PDFs on a tablet, this is the difference between the tool being your primary and it being an experiment.

How it compares to Notion, Roam, Obsidian, and Logseq

• Notion — the mainstream cloud alternative. Better team-collaboration UX, richer visual polish, huge ecosystem of templates. SiYuan wins on data ownership, no subscription, and offline-first work. If your team lives in shared docs with real-time cursors, Notion. If you take notes for yourself and want to actually own them, SiYuan.
• Roam Research — the block-based bidirectional-links pioneer. Beautiful graph views, tight community. SiYuan gives you the same block model plus native mobile plus database views plus PDF annotation, all self-hosted and free.
• Obsidian — the closest philosophical match, and probably SiYuan's most direct competitor for the "knowledge worker who wants files on their machine" reader. Obsidian's plugin ecosystem is more mature; SiYuan's is smaller but growing. Obsidian is not fully open-source (the app is proprietary, only the plugin API is open); SiYuan is fully open-source. Obsidian's mobile parity requires a paid sync tier; SiYuan's is included.
• Logseq — the other major open-source rival. Logseq treats every note as a bullet-list you can nest infinitely; SiYuan treats every note as a page of prose you can also convert to a bullet-list. If you think in outlines, Logseq. If you think in paragraphs, SiYuan. Logseq mobile has historically lagged; SiYuan mobile is native and current.
• RemNote — closest on the spaced-repetition angle. SiYuan ships this via its Riff sub-project; RemNote is a full commercial PKM built around the same feature.

Verdict

Install if any of the following are true: you're paying a Notion / Roam / Obsidian subscription and rethinking it, your work is in a regulated industry that shouldn't send notes to a third-party cloud, you want the block-based PKM pattern but hate cloud lock-in, or you're a student or independent professional who needs a real PKM without a monthly bill.

Skip if: you need real-time multi-user collaboration on the same document (Notion does this better and it's not close), your team is already deep in a shared Notion or Obsidian vault (the switching cost is real), or you need first-class integrations with a specific corporate stack (Slack / Salesforce / etc. — SiYuan has none of these).

One thing to know about the license. AGPL v3 is copyleft. Using SiYuan for personal notes, team notes, or commercial internal use is entirely fine — no obligation triggered. What AGPL restricts is taking SiYuan's code, modifying it, and offering the modified version as a hosted product to other people over a network. If that's not your plan, the license is a non-issue. If it is, get legal advice before you start.

This post is what we learned from reading the project and its ecosystem. A hands-on install-review — importing an existing Notion vault into SiYuan and reporting where the migration lifts and where it stumbles — is queued as a follow-up.

For your agent to install this

You can skip this section — it's the install details your AI agent needs. If you're using Claude Code or Cowork, say "install SiYuan for me" and the agent will read the commands below. This section is mostly relevant if you're deploying SiYuan on a server rather than a personal device.

System / OS

• Desktop: Windows, macOS, Linux — download the installer from the B3log release page or GitHub releases, or install via Microsoft Store on Windows
• Mobile: iOS (App Store), Android (Google Play or F-Droid), HarmonyOS
• Self-hosted server: Docker (recommended) or a package manager on your Linux distribution
• AI Q&A features: optional — requires your own OpenAI or Claude API key

API keys — required for any use

None for the app itself. SiYuan runs entirely offline. Optional API keys unlock specific features:

The paid SiYuan cloud sync tier requires a b3log.org account rather than an API key — buy from b3log.org/siyuan/pricing.html if you want cross-device sync without setting up your own server.

Docker install (self-hosted server)

docker run -d \
  -v /path/to/workspace:/siyuan/workspace \
  -p 6806:6806 \
  -e PUID=1001 -e PGID=1002 \
  b3log/siyuan \
  serve --workspace=/siyuan/workspace --accessAuthCode=your-password

Then open http://localhost:6806 (or your server's IP:6806) in a browser. Full parameter list: docker run --rm b3log/siyuan serve --help.

First-run

On desktop or mobile: open the app, choose a workspace folder (any local folder), and start writing. The default workspace is empty; the built-in user guide is a good starting corpus.

On Docker: same, but you'll access it through the browser and the workspace lives inside the container volume you mounted.