Free practice decks
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96 ready-made decks and 4,800 cards, scheduled with proven spaced-repetition timings. Start a deck in one click, no account needed. Sign up when you want your progress to follow you.
Decks
Hiragana
Learn to read all 46 basic hiragana plus the most common voiced sounds, with example words for every character.
50 cardsKatakana
Learn all 46 basic katakana and the common voiced sounds, each with a real loanword so the shapes stick.
50 cardsN5 kanji
Fifty of the most common JLPT N5 kanji with meanings, on’yomi and kun’yomi readings, and an example word for each.
50 cardsN5 vocabulary
Fifty core JLPT N5 words (everyday verbs, nouns, adjectives and adverbs) with readings, meanings and a natural example sentence for each.
50 cardsN4 kanji
Fifty core JLPT N4 kanji with meanings, on’yomi and kun’yomi readings, and a common example word for each. Free flashcards with spaced repetition.
50 cardsN4 vocabulary
Fifty JLPT N4 words for daily life: plans, travel, opinions and feelings, each with its reading, meaning and an example sentence.
50 cardsN3 kanji
Fifty high-frequency JLPT N3 kanji with meanings, on’yomi and kun’yomi readings, and a common example word for each. Free flashcards with spaced repetition.
50 cardsN3 vocabulary
Fifty JLPT N3 words that bridge everyday and written Japanese: causes and results, feelings, character traits and key adverbs, with example sentences.
50 cardsN2 kanji
Fifty frequent JLPT N2 kanji for news, business and society, with meanings, on’yomi and kun’yomi readings, and an example word for each.
50 cardsN2 vocabulary
Fifty JLPT N2 words from news, work and essays: policies, trends, evidence and nuanced adjectives, each with a reading and example sentence.
50 cardsN1 kanji
Fifty advanced JLPT N1 kanji from news, law and formal writing, with meanings, on’yomi and kun’yomi readings, and an example word for each.
50 cardsN1 vocabulary
Fifty advanced JLPT N1 words from editorials, law and literature, with readings, precise meanings and natural example sentences.
50 cardsSpanish essentials
The first fifty Spanish words and phrases to learn: greetings, core verbs like ser, estar and tener, and everyday nouns with their gender, each with an example sentence.
50 cardsFrench essentials
The first fifty French words and phrases to learn: greetings and polite phrases, core verbs like être, avoir and aller, and everyday nouns with le, la or l’, each with an example.
50 cardsGerman essentials
The first fifty German words and phrases to learn: greetings, sein, haben and the modal verbs, and everyday nouns with der, die or das and their plurals, each with an example sentence.
50 cardsItalian essentials
The first fifty Italian words and phrases to learn: greetings, core verbs like essere, avere and andare, everyday nouns with their article, and numbers.
50 cardsBrazilian Portuguese
The first fifty Brazilian Portuguese words and phrases: greetings, core verbs like ser, estar and ter, everyday nouns and numbers, each with an example.
50 cardsEsperanto basics
Learn how Esperanto works: greetings, the regular word endings, question words like kio and kie, and affixes that build new words, such as mal- and -ej-.
50 cardsKorean Hangul
Learn to read Korean: all 14 basic consonants, 5 double consonants and 21 vowels of Hangul, plus how letters stack into syllable blocks, with Revised Romanization.
50 cardsRussian Cyrillic
Learn to read Russian: all 33 Cyrillic letters with their sounds and an example word each, then 17 first words and phrases, with stress marked.
50 cardsGreek alphabet
Learn the Greek alphabet: all 24 letters with their Modern Greek sounds and uses in math and science, then 25 first words and phrases.
50 cardsArabic alphabet
Learn to read Arabic: all 28 letters with their sounds and joined forms, the short vowel marks, and first greetings in Modern Standard Arabic.
50 cardsHSK 1 vocabulary
Fifty core HSK 1 Mandarin words in simplified characters, with pinyin, meanings and an example sentence for each, from pronouns to time words.
50 cardsJavaScript
Master the JavaScript every developer uses daily: scope, closures, equality, array methods, promises, async/await and the event loop.
50 cardsAdvanced JS
Fifty advanced JavaScript cards: event-loop ordering puzzles, generators and async iteration, this binding, Proxy and Reflect, modules, AbortController and coercion edge cases.
50 cardsTypeScript
Learn the TypeScript you use every day: narrowing, generics, keyof, mapped and conditional types, utility types, satisfies and strict mode, with code on every card.
50 cardsPython
Learn idiomatic Python fast: comprehensions, f-strings, args and kwargs, generators, decorators, context managers and the standard library.
50 cardsGit & terminal
The Git commands and shell skills developers use every day: branching, rebasing, undoing mistakes, pipes, redirects, permissions and processes.
50 cardsJava
Core Java with short snippets: equals vs ==, records, sealed types, collections, generics, exceptions, streams, lambdas and JVM basics.
50 cardsC#
C# and .NET fundamentals with short snippets: value vs reference types, properties, records, nullable reference types, LINQ, async/await and DI.
50 cardsKotlin
Kotlin fundamentals with short snippets: null safety, val vs var, data and sealed classes, extension functions, scope functions and coroutines.
50 cardsSwift
Swift fundamentals with short snippets: optionals, structs vs classes, protocols, enums with associated values, closures, ARC, async/await and SwiftUI.
50 cardsFlutter
Flutter and Dart basics: null safety, futures and streams, stateless vs stateful widgets, setState, hot reload, keys, layout and state management.
50 cardsPHP
Modern PHP 8 with short snippets: strict types, arrays, match, nullsafe and named arguments, enums, readonly, Composer, PDO and password_hash.
50 cardsRuby
Ruby fundamentals with short snippets: blocks, procs and lambdas, symbols, Enumerable, mixins, truthiness, method_missing, gems and Bundler.
50 cardsGo
Go (Golang) fundamentals with short, idiomatic snippets: slices vs arrays, maps, defer, error wrapping, interfaces, goroutines, channels, select and context.
50 cardsRust
Learn the Rust that the compiler keeps asking about: ownership, borrowing, lifetimes, Option and Result, traits, closures, smart pointers and async.
50 cardsC++
Modern C++ in short snippets: references vs pointers, RAII, smart pointers, move semantics, STL containers and algorithms, const, templates and UB.
50 cardsHaskell
Haskell fundamentals with short code: types and type classes, pattern matching, laziness, Maybe and Either, folds, Functor, Applicative and Monad.
50 cardsElixir
Elixir fundamentals with short snippets: immutability, pattern matching, the pipe operator, Enum vs Stream, processes, GenServer, supervisors and mix.
50 cardsx86-64 assembly
x86-64 assembly in Intel syntax: registers and sub-registers, flags, mov and lea, jumps, the stack frame, the System V calling convention and Linux syscalls.
50 cardsRegex
Learn regular expressions for good: anchors, classes, greedy vs lazy quantifiers, groups, lookarounds, flags, replacements and the backtracking trap.
50 cardsHTML & CSS
Fifty HTML and CSS cards: semantic HTML and accessible forms, specificity and cascade layers, flexbox and grid, stacking contexts and z-index, modern units and container queries.
50 cardsReact
Fifty React cards: state and re-rendering, useEffect and cleanup, memoization, refs, context, Suspense and the React 19 APIs like use, useOptimistic and useActionState.
50 cardsVue
Vue 3 fundamentals: ref vs reactive, computed and watch, props and emits, v-model, directives, slots, single-file components and Pinia stores.
50 cardsAngular
Modern Angular: standalone components, signals, inputs and outputs, dependency injection, RxJS basics, @if and @for, routing and OnPush change detection.
50 cardsNext.js
Next.js App Router basics: server vs client components, layouts, route handlers, server actions, caching, metadata, dynamic routes and middleware.
50 cardsNode.js
Node.js fundamentals: the event loop, ESM vs CommonJS, npm, streams, Buffer, fs/promises, process, error handling, worker threads and a basic HTTP server.
50 cardsGraphQL
GraphQL basics: schema types, queries, mutations, subscriptions, resolvers, variables, fragments, N+1 and DataLoader, introspection and GraphQL vs REST.
50 cardsSQL
Learn SQL that holds up in production: joins, grouping, NULL semantics, indexes, transactions, window functions and CTEs.
50 cardsPostgreSQL
PostgreSQL know-how: data types, B-tree and GIN indexes, EXPLAIN, isolation levels, MVCC and VACUUM, JSONB, CTEs, window functions, constraints and roles.
50 cardsMongoDB
MongoDB basics: documents and BSON, CRUD in mongosh, query operators, indexes, the aggregation pipeline, embedding vs referencing, replica sets and sharding.
50 cardsRedis
Redis basics: strings, lists, sets, sorted sets, hashes and streams, TTLs, RDB and AOF persistence, pub/sub, caching patterns, eviction and MULTI/EXEC.
50 cardsComputer science
CS fundamentals: binary and hex, two’s complement, Big-O, stack vs heap, threads and deadlocks, CPU caches, compilers, UTF-8 and floating point.
50 cardsMorse code
Learn International Morse code: all 26 letters, the 10 digits, common punctuation and signals like SOS, each with its rhythm and a memory aid.
50 cardsDS & Algorithms
Big-O for arrays, hash maps, heaps, trees and graphs, sorting trade-offs, and the patterns behind interview problems: two pointers, sliding windows, BFS, Dijkstra and DP.
50 cardsDesign patterns
SOLID, DRY, KISS and YAGNI, plus the Gang of Four patterns used most: singleton, factory, builder, adapter, decorator, observer, strategy, command and more.
50 cardsSoftware testing
Software testing fundamentals: the test pyramid, unit, integration and E2E tests, TDD, mocks vs stubs vs fakes, coverage, mutation and property-based testing.
50 cardsAPI design
API design fundamentals: REST, HTTP methods, status codes, pagination, versioning, OAuth 2.0 and JWT, CORS, OpenAPI, GraphQL, gRPC and webhooks.
50 cardsSystem design
System design fundamentals: load balancers, caching, CDNs, replication and sharding, CAP, consistency, queues, rate limiting and back-of-the-envelope math.
50 cardsCryptography
Cryptography flashcards: AES modes, RSA, elliptic curves, Diffie–Hellman, hashing, HMAC, signatures, password hashing, TLS 1.3 and common pitfalls.
50 cardsData analysis
Data analysis flashcards: summary statistics, data cleaning, joins and group-by in pandas and SQL, pivot tables, chart choices, A/B tests and causation.
50 cardsMachine learning
Machine learning flashcards: supervised vs unsupervised learning, overfitting, bias-variance, regularization, gradient descent, common models and metrics.
50 cardsPrompt engineering
Prompt engineering flashcards: tokens, context windows, temperature, few-shot and chain-of-thought prompting, structured output, RAG and prompt injection.
50 cardsLinux command line
Linux commands and files for sysadmins and LPIC-1 candidates: find and grep, permissions and special bits, fstab, systemd targets, package managers, users, cron and more.
50 cardsBash scripting
Bash scripting flashcards: shebangs, quoting, exit codes, tests, loops, functions, arrays, parameter expansion, redirection, set -euo pipefail and traps.
50 cardsVim
Learn Vim from the keyboard up: modes, motions, operators and text objects, search and :s substitutions, registers, macros, visual mode and windows.
50 cardsNetworking
Computer networking fundamentals: OSI and TCP/IP layers, TCP vs UDP, common port numbers, subnetting and CIDR, DNS, DHCP and ARP, and IPv6 basics.
50 cardsCyber security
Cyber security flashcards: the CIA triad, phishing, XSS, CSRF, SQL injection, MITM, hashing vs encryption, TLS, MFA, least privilege, OWASP and zero trust.
50 cardsDocker
Learn Docker from images and layers to multi-stage builds, volumes, networks and Compose, with the commands and best practices you use daily.
50 cardsKubernetes
Kubernetes fundamentals for developers and CKA or CKAD candidates: Pods, Deployments, Services, storage, probes, resources and scheduling, plus the kubectl commands you use daily.
50 cardsAWS
AWS flashcards: regions and AZs, EC2, S3 storage classes, IAM users, roles and policies, VPC networking, RDS, Lambda, CloudWatch and Route 53.
50 cardsTerraform
Terraform flashcards: HCL, providers, resources, variables and outputs, state and remote backends, plan and apply, modules, count, for_each, drift and import.
50 cardsPeriodic table
Memorize the symbols, names and atomic numbers of the first 50 elements, from hydrogen to tin.
50 cardsChemistry essentials
The core ideas of general chemistry: the mole, pH, bonding, redox, equilibrium, thermodynamics and organic functional groups.
50 cardsOrganic chemistry
SN1, SN2, E1 and E2, stereochemistry, Markovnikov additions, aromatic substitution and carbonyl reactions: the organic chemistry you need for exams, in 50 flashcards.
50 cardsHuman skeleton
Learn the bones of the human skeleton: skull, spine, ribs, arms, hands, legs and feet, with bone counts, joint types and key facts.
50 cardsCell biology
Cell biology essentials: organelles and their jobs, membrane transport, the cell cycle, mitosis and meiosis, DNA replication, transcription and translation.
50 cardsAstronomy
Astronomy basics: the planets, the Sun and how stars live and die, famous stars and constellations, galaxies, cosmic distances, eclipses and exoplanets.
50 cardsPhysics essentials
The core laws and equations of introductory physics: Newton’s laws and kinematics, work, energy and momentum, circuits and electromagnetism, waves and light.
50 cardsCalculus
Memorize the derivatives, integrals, limits and theorems every calculus course relies on, written out in clean LaTeX.
50 cardsStatistics
Learn the statistics every course and data job relies on: variance, the normal distribution, hypothesis tests, regression and probability rules, with formulas in clean LaTeX.
50 cardsLinear algebra
Vectors, matrices, determinants, eigenvalues, orthogonality and the SVD: the linear algebra behind machine learning and engineering, in 50 LaTeX flashcards.
50 cardsNumber theory
Number theory flashcards in LaTeX: primes, gcd and the Euclidean algorithm, congruences, Fermat and Euler, the Chinese remainder theorem and quadratic residues.
50 cardsMechanical engineering basics
First-year mechanical engineering: statics, stress and strain, material properties, simple machines and gears, thermodynamics terms and manufacturing.
50 cardsIntermediate mechanical engineering
Core undergraduate mechanical engineering: bending and torsion, thermodynamic cycles, fluid flow, heat transfer, machine design and vibrations.
50 cardsAdvanced mechanical engineering
Upper-level mechanical engineering: fracture, fatigue, FEA, turbulence, turbomachinery, compressible flow, vibration, control, creep, composites and GD&T.
50 cardsElectrical engineering basics
The basics of electrical engineering: Ohm’s and Kirchhoff’s laws, series and parallel circuits, capacitors, inductors, AC, components and safety.
50 cardsIntermediate electrical engineering
Core undergraduate circuits and electronics: Thevenin and Norton, transients, phasors, AC and three-phase power, op-amps, transistors, logic and filters.
50 cardsAdvanced electrical engineering
Upper-level electrical engineering: Laplace and Z transforms, Bode and Nyquist stability, DSP, transmission lines, Maxwell’s equations, power systems and noise.
50 cardsCivil engineering basics
Learn the core ideas of civil engineering: loads, tension and compression, beams and trusses, concrete and steel, soils, foundations, surveying and roads.
50 cardsIntermediate civil engineering
Undergraduate civil engineering in 50 cards: beam formulas, buckling, concrete and steel design, soils, open channels, hydrology, traffic and water treatment.
50 cardsAdvanced civil engineering
Advanced civil engineering: indeterminate analysis, prestressing, seismic design, consolidation, slope stability, pile capacity, pavements and limit states.
50 cardsChemical engineering basics
The first ideas in chemical engineering: mass balances, stoichiometry, conversion and yield, gas laws, pressure and units, and the main process equipment.
50 cardsIntermediate chemical engineering
The core chemical engineering courses: energy balances, phase equilibrium, distillation, fluid flow, heat transfer, kinetics, reactor design and control.
50 cardsAdvanced chemical engineering
Upper-level chemical engineering: reactor design, transport analogies, phase and reaction equilibrium, shortcut distillation, control, safety and economics.
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