SiYuan

Overview

SiYuan is a privacy-first personal knowledge management system built around Markdown, block-level references, and bidirectional links. It suits people who want connected notes alongside databases and spaced-repetition flashcards, especially if offline use or self-hosting matters.

Its block-based tools cover a lot of ground, but the paid plans have conflicting price and billing terms that are worth resolving before you subscribe.

Key features

SiYuan breaks documents into blocks, with more than 20 block-level element types and more than 10 span-level types. That structure enables block references, backlinks with filtering and search, and relationship graphs at both global and block level. It is a strong fit for building a connected knowledge base; readers who prefer a simpler, page-first notebook may not need this level of structure.

Databases add relations, rollups, and templates, while flashcards use the FSRS spaced-repetition algorithm. Together, these make SiYuan more than a place to collect notes: it can support structured information and review workflows in the same system.

The maker says dynamic loading lets users edit documents containing millions of words smoothly on ordinary computers. AI features use the OpenAI API for writing continuation, translation, summaries, brainstorming, and grammar and spelling corrections. Integrations also include Amazon S3-compatible storage and WebDAV.

SiYuan says its privacy policy does not collect personal information or usage data and that data stays under the user's control on their device. Its multi-device sync is described as end-to-end encrypted and incremental. Those claims make it appealing to privacy-conscious users, while the AI tools and third-party storage integrations are distinct options rather than reasons to assume all data stays local.

Documents use the .sy format, with data stored as JSON. The software is open source, and most features are free, including for commercial use.

Pricing

The Free plan costs nothing, billed $0 Lifetime. It includes basic functions and local storage, so it is the straightforward choice for individual use without third-party sync or backup.

PRO Features is shown at $64 a month, billed Pay once, use for life. It includes basic functions plus third-party S3 and WebDAV data sync and backup integrations; third-party storage itself is not included. The displayed price and lifetime billing wording do not align, so confirm the charge before choosing it.

Subscription is shown at $148 a month, with the pricing page displaying Lifetime while the FAQ also refers to an annual subscription. It includes 8GB of cloud storage. This is the plan for someone who wants cloud storage rather than arranging third-party storage, but the billing terms need clarification. Subscriptions are non-refundable.

A trial subscription can be enabled in SiYuan Desktop under Settings - Account.

Platforms

SiYuan supports Windows, macOS, Linux, iOS, Android, and a web interface, plus a Chrome/Edge extension and API. It also offers Docker self-hosting, with access rights controlled through an authorization code. Offline access is supported, giving it a practical advantage for people who want to work locally or host their own instance.

Who it's for

Choose SiYuan if you want a flexible personal knowledge system that connects notes at block level, adds databases and flashcards, and can work offline or run on your own server. Its local-storage free plan and open-source availability make it especially suitable for users who want control over their setup.

Look elsewhere if you need clearly stated subscription terms before committing, or if a simpler note-taking workflow would make block references, graphs, databases, and spaced repetition unnecessary overhead.

Pros and cons

• Pros: Block-level references, backlinks, and relationship graphs support detailed connections between ideas.
• Pros: Databases, FSRS flashcards, and OpenAI-powered writing tools bring several knowledge-work functions into one application.
• Pros: Offline use, local storage, Docker self-hosting, and stated end-to-end encrypted sync offer meaningful control over where and how data is kept.
• Pros: The free plan includes basic functions with local storage, and the software is open source.
• Cons: The paid plans show prices and billing terms that conflict, making it difficult to judge their actual commitment.
• Cons: The Free plan is limited to local storage; cloud storage and third-party sync and backup integrations are paid-plan features.

Alternatives

Browse our Personal Knowledge Management Software and Note-taking apps lists to compare options across those categories.

• TheBrain is worth considering if you want unlimited thoughts, links, and brains, with all features and private sync up to 1,000 thoughts on its free app plan.
• Logseq is a free alternative for personal use across desktop, mobile, and web platforms.
• Obsidian is another option if its Sync Standard plan suits your needs: it costs $5 a month, billed annually, per user, for one synced vault, 1 GB total storage, and a 5 MB maximum file size.
• Supernotes is a card-based alternative, with a Starter plan capped at 100 cards and an Unlimited plan at £6 a month, billed £72 billed annually.
• Capacities may suit users who prefer its media-upload allowance: the Basic plan includes 5 GB total, then 100 MB per month.
• Mem Agent is an option for readers seeking a different note-taking app, with a free plan that includes 25 messages to Mem and 25 new notes per month.
• TriliumNext Notes is a free, open-source alternative with no paid tiers and no account requirement.
• Heptabase is an alternative with a Pro plan at $11.99 a month, billed monthly, including 100 AI credits per month.

Verdict

SiYuan is a strong choice for people who want a private, block-based knowledge system with links, databases, flashcards, offline access, and self-hosting. Its broad feature set and free local-storage plan are persuasive; the main reason to look elsewhere is the uncertainty around paid-plan pricing and billing. Start with the free plan, and confirm the terms before subscribing.