Now live on the App Store · iPhone & iPad

Learn for life. Remember forever.

Enchiridion turns the world's best knowledge — philosophy, science, money, history, health — into a daily 5-minute habit. The FSRS algorithm schedules the exact moment to review, so what you learn actually sticks.

FSRS-5 algorithm Cited, sourced content Works offline iCloud sync

Good morning

Welcome back

L12
🔥
42day streak

Today

34 / 50 XP

⚔️ Daily Quests

2 of 3
Review 20 cards50 XP
Learn a new topic💎 5
Speed round: 10 in 60s75 XP

Continue learning

Philosophy · Stoicism

12 cards due

9 / 20
🧠 PhilosophyLvl 4

In Camus' The Myth of Sisyphus, what is the fundamental philosophical question?

Whether life is worth living
B
Whether God exists
C
How to achieve happiness
D
What is the nature of truth

Deep Dive

🔖
Philosophy12 min · 14 sections

Stoicism: The Practical Philosophy That Refuses to Die

Marcus Aurelius was the most powerful person on Earth when he wrote what would become one of the most influential personal journals in history. The Meditations weren't written for publication — they were private notes from a man trying to apply Stoicism to the daily grind of running an empire...

Two millennia later, his practical framework — the dichotomy of control, negative visualization, the view from above — is being rediscovered by therapists, athletes, and anyone looking for an operating system for a difficult world.

🔑 Key ideas

  • Dichotomy of control
  • Premeditatio malorum
  • Virtue as the only true good

Cited: Stanford Encyclopedia of Philosophy, A.A. Long (2002), and 11 more sources

2,817+
Quiz Cards
344
Deep Dive Articles
9
Learning Paths
85%
Retention with FSRS

Built for People Who Actually Want to Know Things

Not another flashcard app. A whole knowledge habit, engineered to stick.

🧠

FSRS Spaced Repetition

Powered by the real FSRS-5 algorithm — the gold standard for long-term retention. Reviews are scheduled the moment before you'd forget, so knowledge sticks for life.

🎯

Six Question Types

Multiple choice, true/false, fill-in-the-blank, matching, sequencing, and speed rounds. Your brain stays engaged because the format actually changes.

📚

344 Deep Dive Articles

Go beyond the quiz. Every topic has a beautifully typeset article with 10-15 real sources — Stanford Encyclopedia, NIH, IRS, peer-reviewed journals.

📊

Adaptive Difficulty

7 difficulty levels. The app stays in the 85–90% correct band per-path — challenging enough to grow, easy enough to stay motivated.

🔥

Streaks, Quests & XP

Daily quests, XP milestones, achievements, gems to shield your streak. Learning becomes the good kind of addictive.

☁️

iCloud Sync + Widgets

Progress syncs across iPhone and iPad via CloudKit. Home Screen and Lock Screen widgets keep your streak one tap away.

Six Question Formats. Zero Monotony.

Learning sticks when your brain has to work in different ways. Click any format to see it in action.

💰Taxes & MoneyLvl 3

What is a Roth IRA's key tax advantage over a Traditional IRA?

Contributions are made with after-tax money, so qualified withdrawals are tax-free in retirement
B
You can contribute unlimited amounts each year
C
Employers are required to match your contributions
D
You pay taxes on both the contribution and the withdrawal

Nine Paths. One Habit.

Every path ships with hundreds of quiz cards, dozens of deep dives, and enough depth to last you years.

🏠

Become an Adult

Everything they should have taught you in school

TaxesBudgetingLaundry & HomeInsurance+1 more
311cards
42dives
Explore →
🧠

Philosophy

2,500 years of humanity's best thinking

Ancient GreekStoicismEthicsExistentialism+1 more
379cards
39dives
Explore →
🌍

World History

Understand how we got here

Ancient CivilizationsClassical EraRenaissanceModern Era+1 more
356cards
36dives
Explore →
💰

Taxes & Money

Financial literacy that actually matters

Tax BasicsInvesting 101RetirementDebt Strategy+1 more
340cards
44dives
Explore →
🔬

Science & Nature

Build scientific intuition

PhysicsChemistryBiologyAstronomy+1 more
334cards
48dives
Explore →
❤️

Health & Wellness

Your body is the only place you have to live

Nutrition ScienceExercise & FitnessSleep ScienceMental Health+1 more
358cards
42dives
Explore →
🧩

Psychology & Mind

Understand yourself and others

Cognitive BiasesMental ModelsEmotional IntelligenceBehavioral Economics+1 more
250cards
25dives
Explore →
🎨

Art & Culture

See the world through creative eyes

Art HistoryMusic AppreciationWorld LiteratureCinema & Film+1 more
250cards
34dives
Explore →
🤖

Technology & AI

Understand the systems shaping the future

How Computers WorkHow the Internet WorksAI FundamentalsCybersecurity+1 more
239cards
32dives
Explore →
📚

Sourced from the real stuff

We cite Stanford Encyclopedia of Philosophy, NIH, IRS publications, CDC, the Cambridge Companion series, peer-reviewed journals, and primary texts. No “10 weird facts” listicles. No AI hallucinations. Every card audited.

The Science, Drawn Honestly

What happens to knowledge with and without spaced repetition, based on Ebbinghaus' forgetting curve and FSRS research.

Enchiridion (FSRS)~85% retained
Cramming~15% retained
0%25%50%75%100%Now1d2d4d7d14d30d60d90d

85%

Long-term retention

with FSRS-5 spaced repetition after 90 days

Less study time

vs. re-reading or cramming, for the same recall

5 min

Per day is enough

to build durable knowledge across all 9 paths

Curves illustrative of findings from Ebbinghaus (1885), Cepeda et al. (2006), and modern FSRS research by Jarrett Ye and contributors.

Beyond Flashcards: 344 Deep Dives

Every topic has a long-form companion article. Typeset like a book, sourced like a journal, actually fun to read.

🧠 Philosophy12 min read · 14 sections

Stoicism: The Practical Philosophy That Refuses to Die

Marcus Aurelius was the most powerful person on Earth when he wrote what would become one of the most influential personal journals in history. The Meditations weren't written for publication — they were private notes from a man trying to apply Stoicism to the daily grind of running an empire...

🔑 Key ideas from this dive

  • Dichotomy of control: focus only on what is up to you
  • Premeditatio malorum: mentally rehearse worst outcomes to neutralize them
  • Virtue (arete) is the only true good, external circumstances are indifferents
  • Modern CBT traces directly back to Stoic cognitive techniques
📖Cited: Stanford Encyclopedia, A.A. Long (2002), and 11 more

Linked cards

12 quiz cards reinforce this dive

Flashcards teach the what. Deep Dives teach the why.

Every deep dive article is 12–16 sections, 2,000–4,000 characters each, with 10–15 real sources. Written like a great magazine piece — no filler, no fluff, no SEO word-salad.

344

Articles

12

Avg. sources

11 min

Avg. read

2,828

Tied to cards

  • 🏛️Cites Stanford Encyclopedia of Philosophy, NIH, IRS, CDC, peer-reviewed journals
  • 📝Typeset in serif — designed to read like a book, not a blog
  • 🔖Bookmark, highlight, and revisit any section anytime
  • 🔗Every card links back to the article that covers it in depth

Learning That Feels Like a Game

Streaks, XP, quests, achievements — the same loops that make games addictive, put to work on things that actually matter.

L12

Scholar · Level 12

14,320 XP

720 / 1000 to Level 13

🔥

42

streak

💎

238

gems

🏆

19

badges

🏅

Achievement unlocked

Stoic Scholar

+100 XP

⚔️ Daily Quests

2 / 3
Review 20 cards50 XP
Learn a new topic💎 5
10 correct in a row75 XP
⚔️

Daily Quests

Three new quests each day. Complete them to earn XP and gems.

Review 20 cards • Learn a new topic • Maintain your streak

🛡️

Streak Freezes

Shield your streak with gems so one bad day does not reset your progress.

🔥 42 day streak protected

XP Milestones

Level up your character, unlock new paths, and track lifetime knowledge gained.

Level 12 • 14,320 XP earned

🏆

Achievements

Dozens of unlockable badges for specific learning milestones and consistency.

Stoic Scholar • Polymath • Streak Guardian

How It Works

Four steps. About five minutes a day. The algorithm does the rest.

1
🛤️

Pick Your Paths

Choose the subjects that matter to you. Philosophy? Taxes? Science? You are not stuck on one curriculum.

2
📊

Answer at Your Level

7 difficulty levels mean questions adapt to you. No frustration, no boredom — just the right challenge.

3

FSRS Does the Scheduling

The algorithm shows you a card right before you would have forgotten it. That is why it works.

4
📈

Knowledge Compounds

Every day you practice, you get smarter. Streaks, XP, and quests keep you coming back without thinking.

Live on the App Store

Five minutes a day.
A smarter decade.

Enchiridion is out now on iPhone and iPad. Free to start, with the FSRS-5 algorithm scheduling every review for you. Open the App Store and the first card is one tap away.

Free to download · iPhone & iPad · iOS 17+