FSRS

FSRS for Obsidian

• 🇷🇺
• 🇺🇸 <
• 🇨🇳

Free Spaced Repetition Scheduler — a modern spaced repetition algorithm for Obsidian. The plugin turns your notes into FSRS-based flashcards for effective memorization.

📋 Table of Contents

[toc]

🚀 Features

• 📊 FSRS Algorithm — more efficient than SM-2
• 🎯 Retention Control — 70–97% target level
• ⚡ High Performance — Rust/WASM for fast computations
• 🔄 Dynamic Interface — auto-updating lists
• 📱 Mobile Support — iOS(?), Android(✓)
• 🎨 Flexible Configuration — filtering, sorting, customization
• 📈 Statistics — track your progress

📦 Installation

Via BRAT (for beta testing)

1. Install the BRAT plugin in Obsidian
2. Open Settings → Community plugins → BRAT
3. Add the repository: https://github.com/Evgene-Kopylov/fsrs_plugin
4. Enable the plugin in Settings → Community plugins

Installation Requirements

• Obsidian v1.12.7 or higher
• WebAssembly support (enabled by default)

Platform Support

🐌 Quick Start

1. Create a card – open a note → run the command Add FSRS fields to file header (Ctrl/Cmd+P).
2. Add a review button – use the command FSRS: Insert review button (Ctrl/Cmd+P), or insert a ```fsrs-review-button``` block manually, or enable auto-adding in settings.
3. Insert a table – use the command Insert default fsrs-table (Ctrl/Cmd+P), or create a ```fsrs-table ...``` block manually.
4. Start reviewing – open the table, hover over a file name, and click a rating.

A detailed step-by-step guide with screenshots: Usage Guide

📖 Usage

The fsrs-table Block (SQL-like Syntax)

The fsrs-table block uses SQL-like syntax to customize how cards are displayed.

Basic syntax:

```fsrs-table
SELECT field1, field2 as "Header", field3
ORDER BY field4 DESC
LIMIT 30
```

Available columns:

Block parameters:

• SELECT — choose fields to display (required)
• ORDER BY — sort by a specified field (ASC ascending, DESC descending)
• LIMIT — limit the number of rows (0 uses the value from plugin settings)

Limitations:

• No subqueries, JOIN, aggregations (COUNT, SUM, AVG), GROUP BY, UNION
• WHERE supports only simple conditions: =, !=, <, >, <=, >=, ~ (regex), !~, AND, OR
• The only function available is date_format(field, 'format')
• Unknown field in SELECT, WHERE, ORDER BY — error with field name indicated
• Column order in SELECT is preserved in the displayed table

More: How the SQL parser works

Examples:

1. Urgent cards (by due date):

```fsrs-table
SELECT file as " ", retrievability as "R",
       stability as "S", difficulty as "D",
       due as "Next review"
LIMIT 20
```

1. All cards sorted by date:

```fsrs-table
SELECT *
ORDER BY due ASC
LIMIT 100
```

FSRS Parameters and Configuration

The plugin uses rs-fsrs — the official Rust FSRS implementation by the algorithm authors (L-M-Sherlock). Rationale:

• rs-fsrs — maintained by the FSRS team, synced with the Python reference implementation, actively updated.
• fsrs-rs — third-party implementation, long outdated, incompatible with current FSRS versions.

User-configurable (Settings → FSRS → Algorithm Parameters):

Not yet configurable:

• w weights (17 parameters) — the core of FSRS, determining the forgetting curve. The plugin uses defaults optimized by FSRS authors on the Anki corpus (millions of reviews).
• Parameter optimization on user statistics — not supported. Users cannot retrain weights on their responses. Planned for future versions.

Review Button in Notes fsrs-review-button

```fsrs-review-button
```

FSRS Card Format

FSRS cards are stored in the note's frontmatter under the reviews field:

---
reviews:
  - date: "2026-01-15T10:30:00Z"
    rating: 2
  - date: "2026-01-20T14:15:00Z"
    rating: 3
---

Fields of each review session:

• date — date/time in ISO 8601
• rating — 0 (Again), 1 (Hard), 2 (Good), or 3 (Easy)

Notes:

• reviews can be [] for new cards
• Each review adds a session to the array
• FSRS calculates the next review date based on history
• The plugin adds these fields automatically

🎮 Plugin Commands

Via Command Palette (Ctrl/Cmd+P)

• FSRS: Add FSRS fields to file header
• FSRS: Find cards to review
• FSRS: Review current card
• FSRS: Remove last card review
• FSRS: Show review history
• FSRS: Insert review button
• FSRS: Insert default fsrs-table
• FSRS: Show fsrs-table syntax help

Via the Status Bar

• Button 🔄FSRS: at the bottom of the Obsidian window

⚙️ Settings

FSRS Algorithm Parameters

Default Settings for New Cards

Display Settings

Filter Settings

🧠 The FSRS Algorithm

FSRS is a modern spaced repetition algorithm by Jarrett Ye. Implements FSRS-5 (rs-fsrs v1.2.1). Compared to SM-2:

• Learns memory patterns via machine learning
• Adapts to your memory speed
• Requires 20–30% fewer reviews for the same retention level
• Handles breaks (weeks/months) much better

Key Concepts

• Retrievability (R) — probability of successful recall
• Stability (S) — time it takes for R to decay from 100% to 90%
• Difficulty (D) — information difficulty (affects how stability grows)

The algorithm uses 21 parameters optimized on millions of reviews.

Read more: ABC of FSRS

🛠️ Development

Development happens on GitLab: gitlab.com/Evgene-Kopylov/FSRS-plugin. The GitHub repository is a mirror.

Tech Stack

• Frontend: TypeScript, Obsidian API
• Algorithm: Rust (compiled to WebAssembly)
• Build: esbuild, wasm-pack
• Testing: Rust (cargo test) + TypeScript (vitest)

Rust and TypeScript Responsibility Split

Principle: Rust is the computation core, TypeScript is a thin wrapper for the Obsidian API.

Release Pipeline

The project uses GitLab CI/CD for automated build, test, and release:

Building from Source

Build Requirements

• Node.js 18+
• npm
• Rust (with wasm32-unknown-unknown target)
• wasm-pack
• binaryen (wasm-opt, installed via npm install)

git clone https://gitlab.com/Evgene-Kopylov/FSRS-plugin.git
cd FSRS-plugin
npm install
npm run build

# Install plugin in vault
ln -s "$PWD" /path/to/vault/.obsidian/plugins/fsrs

# Development (optional)
npm run dev

WASM Integration

The plugin uses Rust/WASM for FSRS computations:

• WASM binary is embedded into the plugin via base64
• No network requests — everything runs locally
• High performance — native-level computation

Read more: WASM Integration

📄 License

This plugin is licensed under LGPLv3.

LGPL permits:

• Use in proprietary software
• Requires modified library source code to be open

Main Rights

• ✅ Use (free, including commercial use)
• ✅ Study (access to source code)
• ✅ Distribute
• ✅ Improve

Requirements

• Library modifications must remain under LGPLv3
• Dynamic linking is allowed without disclosing application code
• Maintain copyright notices
• Provide source code when distributing modifications

For Obsidian Users

• Free to use for personal/commercial purposes
• Derivative plugins must be under LGPLv3
• Modifications to Rust WASM components must be under LGPLv3

Full text: LICENSE

🙏 Acknowledgements

• Jarrett Ye (叶峻峣) — author of the FSRS algorithm
• Obsidian Community — inspiration and support
• Rust Community — WASM tooling
• DeepSeek — a powerful and convenient development tool (code, refactoring, localization)
• All contributors — improvements and bug reports

📚 Additional Resources

• Official FSRS Documentation
• Obsidian Forum Discussion
• Issues & Feature Requests
• FSRS Table Usage Guide