Lemma

A modern, FSRS-powered spaced repetition plugin that lives inside your notes.
No separate app. Write, tag, and study directly where your knowledge lives. Cards stay plain Markdown in your vault; review history stays on your device (or your own CouchDB), with backups one command away.

Docs · How to make flashcards in Obsidian · Compared with other plugins · Lemma vs Anki · Buy Me a Momo · Report bug · Request feature

Preview

Desktop and mobile · LaTeX math support · Learning analytics · Custom study sessions

Why Lemma?

Most spaced repetition tools require leaving your knowledge base, exporting notes, and managing a secondary database. Lemma embeds spaced repetition directly in Markdown.

Notes are decks. Add #flashcards to any note, write cards in plain Markdown, and let FSRS handle scheduling.

Features

FSRS Scheduling

Lemma uses FSRS-5 (Free Spaced Repetition Scheduler, via ts-fsrs), a modern scheduling algorithm developed from cognitive science research. It models memory stability and retrievability based on your individual recall patterns.

Cards Live in Notes

Write flashcards directly in any Markdown note without imports or app switching.

---card--- ^fsrs-abc123
What is the powerhouse of the cell?
---
**Mitochondria** — produces ATP through cellular respiration.

Cloze Deletions

The ==c1::mitochondria== is the powerhouse of the ==c2::cell==.

Each cloze deletion is scheduled independently.

Dashboard View

View all decks in a single overview with total cards, due cards, and new cards at a glance.

Custom Study Sessions

Filter review queues by tag, card state (new, learning, due), or configure a card limit for targeted study and exam preparation.

Review Statistics

Analyze learning progress with retention curves, card maturity distribution, interval histograms, and 30-day activity.

Mobile Support

Responsive review interface designed for desktop and mobile, with safe-area insets and touch-optimized navigation.

In-Place Image Occlusion

Review anatomy and technical diagrams in place without vertical shifting. Diagram cards automatically detect image pairs, swapping masks in the exact same viewport position with tap/peek toggling.

Type-In Active Recall

Type answers directly into the review card and get a Correct / Close match / Not correct verdict before revealing FSRS rating buttons.

Guided Card & Deck Creation

Interactive creation modals with dropdown format selection, live syntax previews, and automated deck tagging so you never have to memorize card syntax.

Undo, Backup and Import

Undo the last rating from the review window (Z). Export all schedules, review history and streak data to a JSON file and merge it back on another device, or import cards from a plain text export of another flashcard app or a CSV or TSV file.

Optional CouchDB Sync

Review data is stored on each device (IndexedDB). Optionally connect your own CouchDB or Cloudant instance to sync it across devices.

Quick Start

1. Install from Community Plugins: search for Lemma.
2. Add #flashcards to any note's frontmatter or inline:

---
tags: [flashcards]
---

3. Write a card:

---card--- ^my-first-card
What is spaced repetition?
---
A learning technique that schedules reviews at increasing intervals to maximize long-term retention.

4. Open the Lemma dashboard from the ribbon, the status bar (desktop), or the Command Palette (Open dashboard).

Full syntax documentation: FLASHCARD_GUIDE.md

Card Formats

Lemma supports seven card and study formats:

1. Basic Multi-Line Cards

Multi-line format with full Markdown, LaTeX math blocks, and code formatting. Use ---end--- to explicitly close the card so subsequent headings or notes remain outside the answer.

---card--- ^basic-001
What is the function of the ribosome?
---
Protein synthesis via translation of mRNA.
---end---

2. Single-Line Cards

Fast atomic flashcards on a single line.

What is the capital of Japan?::Tokyo ^single-001

3. Reversed Cards

Generates one card that shows the answer and asks you to recall the question.

Mitochondria:::Powerhouse of the cell ^rev-001

4. Cloze Deletion Cards

Hide one or more concepts in context. Multiple cloze IDs (c1, c2) schedule independent review items.

The ==c1::Ebbinghaus== forgetting curve shows memory decays without ==c2::spaced repetition==. ^cloze-001

5. In-Place Image Occlusion Cards

Swaps occluded diagrams with revealed answers in-place without vertical displacement. Tap the image or press Space / P to peek back and forth between masks before rating.

![[anatomy-masked.png]]::![[anatomy-revealed.png]] ^occlusion-001

6. Type-In Active Recall Cards

Prompts you to type your answer and marks it Correct, Close match, or Not correct before revealing ratings.

?type What is the SI unit of electric current?::Ampere ^typein-001

Or in block format:

---card--- ?type ^typein-002
What is the powerhouse of the cell?
---
Mitochondria

7. Whole-Note Review

Apply FSRS spaced repetition to entire notes by adding #review to the frontmatter or body.

---
tags: [review]
---
# Quantum Mechanics Overview

[!TIP] Add a ^block-id to each card to give it a stable ID.

Keyboard Shortcuts & Gestures

Commands

Settings

Privacy and network access

Lemma is local-first. It has no telemetry, analytics, ads, or crash reporting.

Vault access

Lemma indexes Markdown notes only (vault.getMarkdownFiles()) so it can find notes tagged #flashcards or #review. This is the Vault Enumeration disclosure reported by the community plugin scanner: indexing notes requires enumerating their paths. It does not enumerate or read non-Markdown files, attachments, or data belonging to other plugins.

Data storage

Settings are saved through Obsidian's plugin data API (data.json). Scheduling state and review history are stored in IndexedDB through PouchDB, in a database that is named per vault for new installs (existing installs keep the original shared name, so no data is moved). PouchDB probes localStorage and uses a small cross-tab change marker; this is the Local Storage disclosure reported by the community plugin scanner. Lemma never stores vault content, settings, or review data in localStorage or sessionStorage.

Files Lemma writes and reads

Lemma creates files in your vault only when you run a command that says so: Export review data (backup) writes one Lemma backup <date and time>.json file to the vault root, Import cards from file creates one new deck note, Create new deck and Create card create or edit the note you choose. The import commands read only the single file you select in the file picker. Lemma does not access files outside your vault.

Network access

Lemma makes no network requests by default. It connects to the network only in these cases:

Sync is opt-in. The CouchDB password is saved in the plugin data file (data.json) so sync can reconnect after a restart; Obsidian does not encrypt that file at rest. Use a dedicated CouchDB user that can access only the sync database, and use an https:// URL. An http:// URL sends credentials and review data in clear text.

Installation

Community Plugin Directory

1. Open Settings → Community plugins
2. Click Browse and search for Lemma
3. Select Install, then Enable

Manual Installation

1. Download main.js, manifest.json, and styles.css from the latest release
2. Copy the files into:

   <vault>/.obsidian/plugins/lemma-flashcards/
   

3. Reload Obsidian and enable the plugin under Settings → Community plugins

Release assets contain only main.js, manifest.json, and styles.css. LICENSE and THIRD_PARTY_NOTICES.md remain in the repository if you want to keep the licensing terms alongside the installed copy.

Support

If you find Lemma helpful for your studies and daily knowledge retention, you can support development:

• Buy Me a Momo
• Star the repository on GitHub

Contributing

Contributions, bug reports, and feature requests are welcome.

• Issue tracker: GitHub issues
• Pull requests: Open a pull request against main

License

Lemma is released under the MIT License.

Copyright (c) 2025-2026 Fundaments Work

The permissive terms allow use, copying, modification, merging, publication, distribution, sublicensing, and sale, provided the copyright notice and permission notice are retained. There is no warranty.

License history: releases up to and including v1.1.3 were distributed under the ISC License (also known as OBSD). From v1.1.4 onward, Lemma is MIT. Both are permissive and materially equivalent; users of any version may use, modify, and redistribute it under the terms of the release they received.

• Full license text: LICENSE
• Bundled dependencies: THIRD_PARTY_NOTICES.md

Contributions are accepted under the same terms. See CONTRIBUTING.md for details.