Cheat Sheets

Quick reference for JSON syntax, data types, escaping, and common pitfalls — with examples.

Quick reference for YAML scalars, collections, anchors, block styles, and indentation pitfalls.

Modern JavaScript quick reference: types, arrays, objects, destructuring, promises, and common idioms.

Quick reference for CSS selectors: basic, attribute, pseudo-classes, pseudo-elements, and combinators.

Quick reference for Vim modes, movement, editing, search, and the commands developers use most.

Quick reference for Bash: variables, redirection, pipes, conditionals, loops, and one-liners.

Essential Git commands: setup, staging, branching, merging, undo, and remote workflows.

Docker CLI reference: images, containers, volumes, networks, Compose, and cleanup.

curl flags and patterns: methods, headers, auth, data, cookies, and common API calls.

grep patterns and flags: literal/regex search, inversion, context, files, and one-liners.

GNU find reference: by name/type/size/time, actions, exec, and prune patterns.

Modern Python quick reference: data types, comprehensions, strings, files, and common idioms.

Regex reference: anchors, character classes, quantifiers, groups, lookaround, and common patterns.

Linux file permissions: symbolic and octal modes, common combos, and pitfalls.

Crontab syntax reference: fields, special strings, ranges, and common schedules.

awk one-liners: fields, patterns, actions, FS/OFS, and common text-processing recipes.

Conventional Commits spec: types, scope, breaking changes, and examples.

Markdown reference: headings, emphasis, lists, links, code, tables, and extensions.

HTML reference: structure, semantics, forms, accessibility, and common elements.

HTTP response status codes: 1xx–5xx classes, common codes, and when to use them.

ASCII reference: printable characters, control codes, and decimal/hex/octal values.

npm, pnpm, and Yarn package workflows: install, scripts, semver, lockfiles, configuration, publishing, and npx.

SSH remote access and security: keys, config aliases, file transfer, forwarding, agents, host verification, and permissions.

sed stream editing patterns: substitutions, addresses, ranges, deletion, extended regular expressions, and hold-space workflows.

tar archive workflows: create, extract, inspect, compress with gzip/bzip2/xz, exclude paths, preserve permissions, and transfer archives.

tmux key bindings and commands for prefixes, sessions, windows, panes, copy mode, and configuration.

systemd commands and concepts for service lifecycle, unit files, journal logs, timers, and user services.

kubectl commands and concepts for resources, contexts, logs, exec, labels, scaling, and rollouts.

NGINX directives and commands for server blocks, locations, reverse proxying, TLS, headers, rate limits, and reloads.

Practical OpenSSL reference for keys, CSRs, certificates, TLS inspection, hashing, HMAC, symmetric crypto, and chain verification.

Practical MySQL reference covering connections, SELECT, JOINs, GROUP BY, DDL, indexes, and backup with mysqldump.

Redis CLI and data-type commands covering strings, lists, hashes, sets, sorted sets, key management, pub/sub, and persistence.

.env file format, variable interpolation, precedence, framework loading, and security best practices for environment-based configuration.

ESLint 9 flat config: eslint.config.js structure, rule severity, plugins, ignores, CLI usage, and auto-fix workflows.

TypeScript 5.x reference covering basic types, unions, interfaces, generics, narrowing, utility types, and tsconfig essentials.

Tailwind utility-first reference for spacing, responsive prefixes, state variants, dark mode, @apply, config, and arbitrary values.

Visual Studio Code reference: command palette, keyboard shortcuts, multi-cursor, snippets, settings.json, tasks.json, terminal, and extensions.

Quick reference guide for React 19: Hooks, Server Components, Server Actions, useActionState, and modern UI patterns.

Quick reference guide for Next.js App Router: Routing, Server Components, Server Actions, Caching, and Metadata API.

Quick reference guide for Vue 3: Composition API, script setup, reactivity (ref/reactive), computed, watch, and directives.

Quick reference guide for Svelte 5 Runes ($state, $derived, $effect), components, props, and SvelteKit routing.

Quick reference guide for Angular: Signals, standalone components, control flow syntax (@if, @for), and CLI commands.

Quick reference guide for Node.js core modules: fs/promises, path, stream, http, events, child_process, and Buffer.

Quick reference guide for Express.js: Routing, middleware pipeline, request/response API, error handling, and Router modularization.

Quick reference guide for NestJS: Controllers, Services, Modules, DTO validation, Interceptors, and Dependency Injection.

Quick reference guide for Go: Structs, interfaces, goroutines, channels, slices, maps, and standard CLI commands.

Quick reference guide for Rust: Ownership, borrowing, pattern matching, Option/Result, structs, enums, and Cargo commands.

Quick reference guide for PostgreSQL: JSONB, window functions, indexing, CTEs, and psql CLI.

Quick reference guide for MongoDB: Aggregation pipeline, CRUD operations, indexing, and Mongoose schemas.

Quick reference guide for SQLite: Dot commands, schema definition, pragmas, and CLI flags.

Quick reference guide for Prisma ORM: Schema definition, relations, client queries, and CLI migrations.

Quick reference guide for Drizzle ORM: Table definitions, TypeScript queries, relational queries, and Drizzle Kit.

Quick reference guide for Elasticsearch: Query DSL, bool queries, index mappings, and cluster health APIs.

Quick reference guide for Supabase: JS client SDK, Row Level Security (RLS) policies, storage, and auth.

Quick reference guide for Terraform: HCL syntax, resource blocks, state manipulation, and CLI commands.

Quick reference guide for GitHub Actions: Workflow YAML syntax, matrix builds, custom secrets, and triggers.

Quick reference guide for Docker Compose: Specification format, service definitions, volume/network mounts, and CLI.

Quick reference guide for AWS CLI: S3 sync/copy, EC2 management, Lambda invoke, IAM policies, and CloudWatch.

Quick reference guide for Helm: Helm install/upgrade/rollback, chart structure, templates, and CLI.

Quick reference guide for Ansible: Playbook syntax, inventory files, roles structure, and CLI modules.

Quick reference guide for Linux Networking: ip, ss, netstat, dig, traceroute, iptables, and ufw.

Quick reference guide for Caddy Server: Caddyfile directives, reverse proxy, automatic HTTPS, and headers.

Quick reference guide for Prometheus & PromQL: Metric types, rate functions, selectors, and alert rules.

Quick reference guide for Vitest & Jest: Test suite syntax, assertion methods, mocks, spies, and async testing.

Quick reference guide for Playwright: Locators, page actions, assertions, fixtures, and CLI runner.

Quick reference guide for pnpm: Workspace filters, monorepo commands, lockfile management, and store.

Quick reference guide for Vite: vite.config.ts, plugin configuration, environment variables, and dev server.

Quick reference guide for Python FastAPI: Path operations, Pydantic v2 schemas, dependency injection, and async.

Quick reference guide for Laravel: Artisan CLI commands, Eloquent ORM queries, Blade directives, and routing.

Quick reference guide for Java Spring Boot: Annotations, REST controllers, Spring Data JPA, and application properties.

Quick reference guide for GraphQL: Schema Definition Language (SDL), queries, mutations, resolvers, and subscriptions.

Quick reference guide for JWT & OAuth 2.0: Structure, authorization code grant + PKCE, client credentials, and claims.

Quick reference guide for Web Security Headers: CSP, HSTS, X-Frame-Options, CORS, and security policy rules.

Quick reference guide for Protocol Buffers (proto3): Syntax, scalar types, messages, enums, services, and protoc CLI.

Quick reference guide for Web Crypto API: SubtleCrypto hashing, HMAC, key generation, encryption, and JWK export.

Quick reference guide for WebSocket Protocol: JS WebSocket API, connection handshake headers, ping/pong, and frames.

Quick reference guide for Cypher & Neo4j: MATCH, CREATE, MERGE, relationship patterns, and graph traversal.

Quick reference guide for Zustand & Redux Toolkit: Store creation, middleware, actions, selectors, and async thunks.

Quick reference guide for Native DOM & Web APIs: querySelector, event delegation, MutationObserver, IntersectionObserver, and Storage.

Quick reference guide for Web Accessibility (a11y): ARIA roles, screen reader attributes, focus management, and keyboard navigation.

Quick reference guide for Webpack 5: Entry/output, loaders, plugins, code splitting, and dev server.

Quick reference guide for Prettier & Biome: Configuration rules, CLI commands, formatting options, and ignore files.

Quick reference guide for Yarn v4 Berry: Workspaces syntax, Plug'n'Play (PnP) commands, constraints, and plugins.

Quick reference guide for Zsh & Fish Shell: Configuration files, aliases, custom prompts, functions, and environment variables.

Quick reference guide for Advanced Git: Interactive rebase, cherry-pick, bisect, reflog recovery, and worktrees.

Quick reference guide for GDB & LLDB: Breakpoints, stepping execution, inspecting memory, watchpoints, and stack traces.

Quick reference guide for Advanced Regex: Positive/Negative lookaheads, lookbehinds, named capture groups, and backreferences.

Quick reference for writing Dockerfiles: base images, instructions, multi-stage builds, best practices, and .dockerignore.

Quick reference for writing Kubernetes YAML: Pod, Deployment, Service, Ingress, ConfigMap, and common kubectl apply patterns.

Quick reference for the OpenAPI 3.1 specification: paths, operations, schemas, components, security, and spec organization.

Quick reference for JSON Schema: core keywords, validation rules, arrays, nested objects, references, and common patterns.

Quick reference for JSONPath expressions: root, child, wildcard, filters, slices, and JSONPath-Plus extensions.

Quick reference for writing efficient SQL: SELECT, JOINs, aggregation, window functions, CTEs, and query performance basics.

Quick reference for Content-Security-Policy: source expressions, directive reference, common policy templates, and reporting.

Quick reference for on-page SEO: robots.txt, meta tags, sitemap.xml, Open Graph, and JSON-LD structured data for search engines.

Quick reference for Base64 and binary encoding: padding, URL-safe variants, hexadecimal, binary, and common conversion patterns.

Quick reference for hash functions and checksums: MD5, SHA-1, SHA-2, SHA-3, HMAC, CRC32, and when to use each.

Quick reference for identifier and token formats: UUID v1-v8, ULID, NanoID, BIP39 mnemonics, and common token grammars.

Quick reference for time handling: ISO 8601, Unix timestamps, UTC, offsets, DST, and formatting patterns across languages.

Quick reference for scalable vector graphics: viewBox, shapes, paths, transformations, gradients, and optimization basics.

Quick reference for CSS layout: Flexbox alignment, Grid template areas, auto-fit, gap, and when to reach for each layout model.

Quick reference for CI/CD configuration: GitHub Actions, GitLab CI, Jenkins, CircleCI, and Travis CI syntax compared.

Quick reference for Apache HTTP Server: virtual hosts, directives, URL rewriting, .htaccess, and security hardening.

Quick reference for AWS IAM and S3 policies: JSON policy structure, actions, conditions, resource ARNs, and least-privilege patterns.

Quick reference for SSL/TLS certificates: CSR generation, certificate types, chain files, validation, and openssl workflows.

Quick reference for CORS and API headers: preflight requests, response headers, Authorization, caching, and common configurations.

Quick reference for configuration formats: XML structures, TOML tables/arrays, and when to choose each serialization.

DNS record types (A, AAAA, CNAME, MX, TXT, NS, PTR, SOA), lookup commands, and troubleshooting flows.

CloudFormation template structure, resources, parameters, outputs, intrinsic functions, and CLI workflows.

Azure Resource Manager template structure, resources, parameters, variables, outputs, and deployment commands.

Kubernetes CPU/memory requests, limits, quotas, limit ranges, and resource sizing guidance.

Entity-relationship notation (crow's foot, Chen), cardinality, keys, normalization, and schema design patterns.

GPG key generation, symmetric and asymmetric encryption, signing, key management, and revocation.

Webhook concepts, payload formats, signatures, retries, security, and local testing patterns.

HTTP methods, status codes, request structure, Postman collections, environments, and test assertions.

URL anatomy (scheme, host, port, path, query, fragment), encoding rules, and parsing across languages.

SemVer rules, version bumping, pre-release and build metadata, ranges, and comparison logic.

CSV format rules, delimiters, quoting, escaping, parsing pitfalls, and common transformations.

Service worker lifecycle, caching strategies, fetch handling, registration, and offline patterns.

Web platform Baseline status, feature detection, caniuse workflows, and cross-browser testing strategies.

QR code structure, versions, error correction levels, encoding modes, and generation/scanning guidance.

Prompt structure, roles, few-shot examples, chain-of-thought, and common techniques for better LLM output.

What tokens are, tokenization, counting methods, context windows, and cost estimation for LLMs.

TLS 1.3 and 1.2 handshake steps, cipher suites, certificate validation, and troubleshooting.

Migration workflows, up/down patterns, expand-contract, versioning, and zero-downtime strategies.

Stored procedure syntax, parameters, control flow, error handling, and best practices across SQL dialects.

Common TCP/UDP port numbers, port ranges, and how to check open ports and services.

IPv4/IPv6 formats, CIDR notation, subnet masks, address classes, and subnet calculation.

Common MIME types, Content-Type headers, multipart forms, and how to detect and set them correctly.