Best Open-Source Flashcard Apps 2026: 6 Options Compared
Best open-source Flashcard Apps compared: Anki, AnkiDroid, hashcards, SiYuan and 2 more, with licenses, platforms and prices from official pages checked October 24, 2026.
•3 min read•Learning & Everyday Apps
Quick comparison
| Tool | Price | Platforms | Best for | Tested |
|---|---|---|---|---|
| Anki | Free (Desktop app free on all major platforms; AnkiWeb sync free; AnkiDroid free. AnkiMobile (iOS) is an official app with no price shown on the page) | Windows, macOS, Linux, Android, iOS | Heavy studying with shared decks | Docs only |
| AnkiDroid | Free (Free and open source Anki client for Android) | Android | Reviewing on an Android phone | Docs only |
| hashcards | Free (Free and open source) | Command line, Web browser | Text-editor and git users | Docs only |
| SiYuan | Free (README: most features are free, even for commercial use; some features are for paid members) | Desktop, Mobile, Self-hosted (Docker) | Notes and cards in one app | Docs only |
| Nibomo | Free (Open-source code is MIT; the app listings and any paid plan were not checked) | iPhone, iPad, Mac, Android, Web | AI-assisted card writing | Docs only |
| Logseq | Free (open-source outliner and knowledge base with no paid plan listed) | Windows, macOS, Linux, Web, iOS | Cards from an outliner | Docs only |
Independent comparison. Paid placements are labelled separately; editorial links earn no affiliate commissions. Learn more.
Good fit if
- You study for exams and want shared decks (Anki is the pick)
- You mostly review on an Android phone (AnkiDroid is the pick)
- You keep everything in plain text under git (hashcards is the pick)
- Your cards come out of your daily notes (Logseq is the pick)
Not ideal if
- You cannot host, patch and back up a server yourself and want a vendor to run it
Spaced repetition, showing a card again just before you would forget it, is what makes flashcard apps work, and the open-source options differ mostly in how you write and store cards. Anki is the established choice with a huge shared deck library and add-ons, and AnkiDroid brings the same collection to Android for free. Hashcards takes the opposite approach: cards are plain text files you edit in any editor and schedule with FSRS, a modern spacing algorithm. SiYuan, a note-taking workspace, includes spaced repetition among its features, which suits people who want notes and cards in one place. Nibomo is a newer MIT-licensed app that adds AI card creation and apps for several platforms. Choose Anki if you want the biggest community and do not mind an older interface; choose hashcards if you live in a text editor and version control; choose SiYuan if your cards come from your notes. The trade-off to watch is sync: Anki and AnkiDroid use the free AnkiWeb service, while text-file tools leave syncing to you through git or a cloud folder. Licences come from each repository; some products also have paid sync or app-store versions that were not priced here.
Anki
The default with AGPL-licensed desktop apps, free AnkiWeb sync and a huge deck library. The iOS app, AnkiMobile, is separate and check the App Store for the current price.
Price: Free (Desktop app free on all major platforms; AnkiWeb sync free; AnkiDroid free. AnkiMobile (iOS) is an official app with no price shown on the page) (Anki pricing, checked 2026-10-22).
Platforms and license: Windows, macOS, Linux, Android, iOS. AGPL-3.0-or-later (some contributed parts BSD-3) (open source) (license source).
Project activity: 32.3k GitHub stars · latest release 26.09.3 (Sep 23, 2026) · last commit Oct 27, 2026
Best for: Heavy studying with shared decks.
AnkiDroid
GPL-3.0 Android client for Anki collections, free on Android. Pairs with the desktop app and AnkiWeb for sync.
Price: Free (Free and open source Anki client for Android) (AnkiDroid pricing, checked 2026-10-24).
Platforms and license: Android. GPL-3.0 (open source) (license source).
Project activity: 12.1k GitHub stars · latest release v2.25.3 (Oct 17, 2026) · last commit Oct 27, 2026
Best for: Reviewing on an Android phone.
Worth knowing: License taken from the repository metadata and LICENSE file; description from the project README. No paid plan was checked.
hashcards
Apache-2.0 plain-text system: write cards in Markdown-like files, schedule with FSRS, track changes with git. Editing a card resets its progress.
Price: Free (Free and open source) (hashcards pricing, checked 2026-10-24).
Platforms and license: Command line, Web browser. Apache-2.0 (open source) (license source).
Project activity: 1.2k GitHub stars · latest release v0.5.0 (Oct 9, 2026) · last commit Oct 26, 2026
Best for: Text-editor and git users.
Worth knowing: README: plain-text spaced repetition system that stores cards as text files and schedules with FSRS.
SiYuan
AGPL-3.0 note workspace whose README lists flashcard spaced repetition. Most features are free but some are for paid members, so check the pricing page.
Price: Free (README: most features are free, even for commercial use; some features are for paid members) (SiYuan pricing, checked 2026-10-24).
Platforms and license: Desktop, Mobile, Self-hosted (Docker). AGPL-3.0 (open source) (license source).
Project activity: 47k GitHub stars · latest release v3.8.8 (Oct 20, 2026) · last commit Oct 27, 2026
Best for: Notes and cards in one app.
Nibomo
MIT-licensed flashcards with FSRS review, AI-assisted card creation and apps for iPhone, iPad, Mac, Android and the web. Young project with a small user base.
Price: Free (Open-source code is MIT; the app listings and any paid plan were not checked) (Nibomo pricing, checked 2026-10-24).
Platforms and license: iPhone, iPad, Mac, Android, Web. MIT (open source) (license source).
Project activity: 102 GitHub stars · latest release v1.37.0 (Oct 22, 2026) · last commit Oct 26, 2026
Best for: AI-assisted card writing.
Worth knowing: README: AI-powered open-source flashcards with FSRS review. App store prices and hosted limits were not read.
Logseq
AGPL-3.0 outliner where any block tagged as a card becomes a flashcard, per the Logseq docs. A good fit if your notes already live there.
Price: Free (open-source outliner and knowledge base with no paid plan listed) (Logseq pricing, checked 2026-10-22).
Platforms and license: Windows, macOS, Linux, Web, iOS. AGPL-3.0 (open source) (license source).
Project activity: 45.4k GitHub stars · latest release 2.0.2 (Oct 7, 2026) · last commit Oct 27, 2026
Best for: Cards from an outliner.
Which one to pick
- You study for exams and want shared decks: Anki
- You mostly review on an Android phone: AnkiDroid
- You keep everything in plain text under git: hashcards
- Your cards come out of your daily notes: Logseq
Limits of this review
Docs-only for Anki, AnkiDroid, hashcards, SiYuan, Nibomo, Logseq: we did not install or run them, so feature claims come from vendor pages. Vendor prices and free limits change; confirm on the linked pricing page before you commit.
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Kevin Fan
Kevin Fan is a SaaS founder. He runs Free Instead Of, which tracks free and open-source alternatives to paid software and checks each price and free-plan limit against the vendor's own pages.
Methodology
Based on official pricing, license and product pages checked between 2026-10-22 and 2026-10-24: Anki, AnkiDroid, hashcards, SiYuan, Nibomo, Logseq. Prices, free limits and licenses are the figures shown on those pages on those dates. No tool on this page was installed or run. No accounts were created.