Developer Reference Tools — Cheatsheets and Calculators for DevOps

🐍 Python

• Python Reference new — Comprehensions, dataclasses, context managers, itertools, pathlib, pattern matching, functools, collections, typing.
• Pydantic V2 Reference — BaseModel, validators, settings, serialization, TypeAdapter
• Zod Reference — schemas, safeParse, transforms, React Hook Form, advanced patterns
• SQLAlchemy 2.0 Reference — Mapped, select(), relationships, async, Alembic
• Prisma Reference — schema, CRUD, relations, raw queries, transactions
• Kubernetes Gateway API Reference — HTTPRoute, GatewayClass, traffic splitting, GRPCRoute
• FastAPI Reference — Pydantic models, JWT auth, async SQLAlchemy, middleware, testing
• Rust Reference — ownership, borrowing, Result/Option, Cargo, traits, async/Tokio
• Python Type Hints Reference — TypeVar, Protocol, Literal, TypedDict, overload, ParamSpec, @dataclass.
• Python asyncio Reference — async/await, gather, TaskGroup (3.11), Queue, Lock, Semaphore, async generators.
• pytest Reference — fixtures, parametrize, markers, monkeypatch, tmp_path, capsys, conftest.py.
• Python Packaging Reference — venv, uv, pip, pyproject.toml (PEP 621), Poetry, PyPI publishing.

☕ Java / JVM

• Java Reference new — Java 17–21: records, sealed classes, pattern matching, streams, Optional, virtual threads, Maven/Gradle.

⚡ JavaScript / TypeScript / Node.js

• Ruby Reference new — Blocks/Procs/Lambdas, Enumerable (map/group_by/reduce), Hash patterns, Modules+Mixins, error handling, Bundler.
• PHP 8.x Reference new — Match expressions, Enums, readonly classes, nullsafe operator, array functions, PDO, Composer, PHPStan.
• JavaScript ES6+ Reference new — Destructuring, async/await, array methods, classes, ESM modules, Map/Set, generators, error handling.
• TypeScript Reference — tsconfig, Partial/Pick/Omit, generics, type guards, discriminated unions, satisfies.
• ESLint Reference — flat config, TypeScript rules, disable comments, lint-staged
• Prettier Reference — config, ESLint integration, format on save, plugins
• AWS SDK v3 Reference — S3, DynamoDB, SES, SQS, SSM, Lambda (TypeScript)
• Vitest Reference — config, mocking, React Testing Library, snapshots, MSW
• Jest Reference — config, matchers, mocking, async tests, snapshots
• React Testing Library Reference — queries, userEvent, async, MSW, accessibility
• Vite 6 Reference — config, environment variables, assets, library mode, plugins
• SWR Reference — useSWR, mutations, infinite scroll, revalidation, Next.js
• Webpack 5 Reference — config, loaders, code splitting, dev server, Module Federation
• Cypress Reference — selectors, assertions, custom commands, intercepting, component tests
• Playwright Reference — locators, actions, page objects, API mocking, CI
• tRPC v11 Reference — routers, procedures, Next.js, React Query, type safety
• Node.js Reference new — fs/promises, http, EventEmitter, streams, child_process, worker_threads, crypto, built-in test runner.
• Turborepo Reference — task caching, remote cache, filtering, monorepo packages
• esbuild Reference — CLI, JavaScript API, loaders, plugins, build scripts
• Bun Reference — runtime, HTTP server, package manager, bundler, built-in SQLite
• Python asyncio Reference — coroutines, TaskGroup, Queue, Semaphore, run_in_executor
• Express.js Reference — routing, JWT auth, Zod validation, rate limiting, cluster mode
• npm Reference — install/ci, package.json scripts, npx, nvm/fnm/volta, workspaces monorepo.
• GraphQL Reference new — Queries, mutations, fragments, SDL schema, resolvers, N+1 with DataLoader, Apollo Client hooks.
• React Reference new — React 18/19: memo, hooks, useEffect patterns, Context, custom hooks, Server Components.
• WebSocket Reference — native API, Socket.IO, Nginx config, Kubernetes ingress, scaling
• Svelte 5 & SvelteKit Reference — runes, stores, routing, form actions, adapters
• Vue.js 3 Composition API Reference — ref/reactive, composables, props, Pinia, Vue Router
• Next.js App Router Reference — Server Components, caching, Server Actions, middleware
• shadcn/ui Reference — install, components, forms, data table, theming
• TanStack Query v5 Reference — useQuery, useMutation, cache invalidation, Next.js
• React Hooks Reference — useState, useEffect, useContext, useRef, useMemo, useCallback, custom hooks.

🐹 Go   🦀 Rust

• Go Reference — go mod, cross-compile, go test -race, go work, build tags, CGO_ENABLED=0.
• Go Testing Reference — t.Run, table tests, testify, httptest, mocking, coverage, benchmarks, fuzz.
• Cargo & Rust Reference — cargo build/check/test, Cargo.toml features, clippy, Criterion benchmarks, musl static binary.
• Rust Error Handling Reference — Result, ?, thiserror, anyhow, Box<dyn Error>, custom error types.

☸️ Kubernetes

• kubectl Reference — get/apply/delete, logs with selectors, exec -it, rollout undo/restart, describe, jsonpath, kubectx.
• Kubernetes YAML Reference — Deployment, Service, ConfigMap, Secret, HPA, PodDisruptionBudget, resource limits.
• Kubernetes Networking Reference new — Services, Ingress, NetworkPolicy, DNS, Gateway API, Istio, debugging commands.
• Kubernetes Storage Reference new — PV, PVC, StorageClasses (AWS/GKE/Azure), reclaim policy trap, StatefulSet volumeClaimTemplates, volume expansion.
• Prometheus & PromQL Reference new — Metric types, rate/irate/increase, histogram_quantile, aggregations, alerting rules, K8s monitoring queries.
• Grafana Reference — panels, variables, alerting, PromQL patterns, file-based provisioning
• Kustomize Reference — overlays, patches, ConfigMapGenerator rolling restarts, ArgoCD integration
• etcd Reference — K8s backing store backup/restore, etcdctl ops, compaction, TLS certs
• Helmfile Reference — multi-Helm release management, environments, selectors, secrets, hooks
• HashiCorp Vault Reference — dynamic secrets, Kubernetes auth, policies, Agent sidecar injector
• cert-manager Reference — ClusterIssuer, Let’s Encrypt HTTP-01/DNS-01, Certificate resource, Vault PKI, troubleshooting
• Podman Reference — rootless containers, pods, K8s YAML generation, systemd Quadlets, Docker migration
• HashiCorp Consul Reference — service discovery, DNS, KV store, consul-template, Connect mesh, ACLs
• Kubernetes RBAC Reference new — Roles, ClusterRoles, RoleBindings, ServiceAccounts, least-privilege patterns, Workload Identity (IRSA/GKE/AKS), common mistakes.
• Drizzle ORM Reference — schema, queries, relational API, migrations, edge runtimes
• Kubernetes Operators Reference — CRDs, controllers, RBAC, status conditions, kubebuilder
• gRPC Reference — Protobuf, Go/Python servers, streaming, gRPC-Gateway
• Protocol Buffers & Buf CLI Reference — messages, services, code generation, Connect protocol
• Storybook 8 Reference — stories, controls, interactions, MSW mocking, visual testing
• Kubernetes NetworkPolicy Reference — default deny, egress, CIDR, three-tier patterns
• Istio Reference — VirtualService, DestinationRule, mTLS, Gateway, AuthorizationPolicy, observability
• Velero Reference — K8s backup, restore, cross-cluster migration, hooks, restic/kopia
• Linkerd Reference — service mesh, golden metrics, mTLS, ServiceProfile, traffic split
• OPA & Gatekeeper Reference — Rego policies, ConstraintTemplate, audit mode, conftest CI
• Skaffold Reference — K8s local dev loop, file sync, profiles, remote debug, Helm/Kustomize deploy
• Kyverno Reference — K8s policy engine, validate/mutate/generate, kyverno test, image verification
• Trivy Reference — container scanning, K8s cluster audit, IaC misconfigs, secrets, CI/CD integration
• Cosign/Sigstore Reference — container image signing, keyless OIDC, SBOMs, K8s policy enforcement
• Harbor Reference — self-hosted container registry, RBAC, Trivy scanning, replication, webhooks
• Tekton Reference — K8s-native CI/CD, Tasks, Pipelines, Triggers, tkn CLI, Tekton Hub
• KEDA Reference — event-driven autoscaling, Kafka/SQS/Redis scalers, ScaledJob, scale to zero
• Knative Reference — autoscale-to-zero, eventing with brokers/triggers, traffic splitting, GitOps
• OpenCost Reference — K8s cost allocation by namespace/label, cloud billing, Grafana integration
• External Secrets Operator Reference — Vault, AWS SM, GCP, Azure Key Vault secret sync
• Sealed Secrets Reference — kubeseal, GitOps-safe encrypted secrets, scopes, key rotation
• Karpenter Reference — K8s node autoscaling, NodePool, spot/Graviton cost savings, consolidation
• Kubernetes Troubleshooting Reference — CrashLoopBackOff, OOMKilled, Pending pods, ImagePullBackOff, debugging playbooks.
• Kubernetes Resource Types — Every K8s object: Pod, Deployment, HPA, RBAC, CRDs with YAML examples.

🏗️ Infrastructure & IaC

• Terraform Reference — init, plan -out, apply/destroy, state mv/rm/import, workspaces, TF_VAR_*, modules.
• OpenTofu Reference — migration from Terraform, providers, resources, backends, workspaces, testing
• Temporal Reference — workflows, activities, signals, TypeScript SDK, production patterns
• NGINX Ingress Controller Reference — annotations, TLS, rewrites, rate limiting, canary
• Pulumi Reference — IaC with TypeScript/Python, stacks, AWS/K8s resources, deploy & CI
• Ansible Reference new — ansible-playbook flags, ad-hoc, inventory, roles, vault, loops/block-rescue, ansible.cfg.
• ArgoCD & GitOps Reference new — Applications, ApplicationSet generators (list/cluster/git/pull-request), sync waves/hooks, RBAC + SSO, notifications, ArgoCD vs Flux 2 comparison.
• k9s Reference — shortcuts, Popeye linter, XRay dependency graph, aliases for CRDs, plugins
• Crossplane Reference — K8s-native infra, Providers, Managed Resources, XRD Compositions, Claims
• Cilium Reference — eBPF CNI, L7 HTTP/DNS/Kafka policy, Hubble network observability
• Argo Workflows Reference — DAG, steps, artifacts, CronWorkflow, K8s ML pipelines
• Argo Events Reference — EventSource, Sensor, Triggers — webhook, Kafka, cron, conditions
• Go Modules Reference — go.mod, go get, workspaces, GOPROXY, private repos
• Argo Rollouts Reference — canary, blue-green, AnalysisTemplate, Prometheus-gated rollback
• NATS Reference — pub/sub, JetStream streams, KV store, request/reply, clustering
• Falco Reference — K8s runtime security, custom rules, Falcosidekick routing, tuning
• Dapr Reference — distributed app runtime, service invocation, pub/sub, state, secrets
• Flux v2 Reference — GitOps bootstrap, HelmRelease, image automation, SOPS encrypted secrets
• RabbitMQ Reference — exchanges, dead-letter queues, consumer patterns, vs Kafka
• Helm Reference — install/upgrade/rollback, templating (tpl/lookup), values override, chart dependencies, OCI.
• Dockerfile Best Practices — Multi-stage builds, layer caching, non-root user, .dockerignore, health checks, size optimisation.
• Docker Commands Reference — docker run/build/compose, multi-stage builds, health checks, prune.
• Docker Compose Reference — services, networks, volumes, profiles, depends_on, deploy/replicas, env_file.

☁️ Cloud CLIs

• AWS CLI Reference — configure profiles, S3 sync/cp, EC2 describe, ECS/EKS, IAM, SSM, CloudFormation, query/filter.
• gcloud CLI Reference — auth, config, compute/container/run/storage, IAM, service accounts, GKE.
• Azure CLI Reference — az login, resource groups, AKS, App Service, Storage, Key Vault, role assignments.

🔧 DevOps Config & Automation

• YAML Reference new — Syntax, types, multi-line strings, anchors, K8s patterns, GitHub Actions patterns, gotchas.
• GitHub Actions Reference — Events, matrix, caching, OIDC, Docker push, composite actions, reusable workflows.
• Git Advanced Reference — interactive rebase, bisect, hooks, stash, reflog recovery
• OpenAPI 3.1 Reference — schemas, components, webhooks, SDK generation, linting
• gh CLI Reference — pr create/merge, issue create, run view, auth, release, api endpoint queries.
• Makefile Reference — .PHONY, self-documenting help, := vs = vs ?=, $@ $< $^, pattern rules, ifeq.
• GitLab CI/CD Reference new — .gitlab-ci.yml: stages, rules (replaces only/except), needs DAG, Docker builds, caching, artifacts, environments.
• Jaeger Reference — distributed tracing, OTel integration, sampling, production setup
• nginx Reference — server blocks, location matching, proxy_pass, SSL, rate limiting, upstream, headers.
• pnpm Reference — install, store, workspaces, catalog, CI
• Rollup Reference — config, plugins, tree shaking, library builds, formats
• Linux Admin Reference — systemctl, journalctl, crontab, user/group management, firewalld, disk/memory tools.

🌐 Networking, HTTP & Security

• SSH Reference — Config file, ProxyJump, port forwarding, key management, sshd_config hardening.
• OpenSSL Reference — Inspect certs, generate keys/CSRs, test TLS handshake, convert PEM/DER/PFX.
• curl Reference — 30+ flags: POST JSON, bearer token, file upload, retry, timing, mTLS.
• HTTP Status Codes — All 40+ codes: 401 vs 403, 502 vs 503 vs 504 explained.
• HTTP Security Headers — HSTS, CSP, X-Frame-Options, CORS. Risk ratings + nginx snippets.
• DNS Record Types Reference — A, AAAA, CNAME, MX, TXT, SPF, DKIM, DMARC with dig commands.

🔢 Data, SQL & Databases

• SQL Reference — JOINs, window functions, CTEs, upsert, pagination, JSONB, explain analyze.
• PostgreSQL & psql Reference — psql meta-commands, pg_stat_activity, EXPLAIN ANALYZE, pg_dump, CONCURRENTLY.
• AWS CDK Reference — L2/L3 constructs, ECS Fargate, Aspects, CDK Nag, Jest testing
• PostgreSQL Advanced SQL Reference — window functions, CTEs, JSONB, EXPLAIN ANALYZE, indexes
• SQLite Reference — CLI, WAL mode, JSON, window functions, transactions, Litestream
• HTTP Headers Reference — Cache-Control, security headers, CORS, compression, auth
• MySQL & MariaDB Reference new — mysql client, user management, EXPLAIN type column, index types (covering/FULLTEXT/INVISIBLE), transactions, backup, performance schema.
• Redis Reference — String/Hash/List/Set/ZSet commands, TTL, pub/sub, pipelines, Lua scripting, ACL.
• Apache Kafka Reference new — Producer (acks/idempotent/linger.ms/compression), Consumer (auto.offset.reset/CooperativeStickyAssignor/max.poll), consumer group lag + offset reset, exactly-once semantics, kafka-topics/kcat commands, broker production tuning.
• Elasticsearch & OpenSearch Reference new — Query DSL (bool/match/term/range/multi_match), aggregations, ILM, mappings (text vs keyword), performance diagnostics.
• MongoDB Reference new — mongosh, CRUD, update operators ($set/$push/$pull), aggregation pipeline, TTL/text/partial indexes, explain().
• jq Reference — 40+ filters: select, map, reduce, env, curl+jq, kubectl+jq, CSV output.

🐚 Command Line & Scripting

• Linux Networking Reference new — ip, ss (replaces netstat), tcpdump BPF filters, nmap scanning, dig, iptables/nftables, connectivity debug playbook.
• Linux Performance Tuning Reference — perf profiling, flame graphs, BCC/eBPF, iostat, strace, fio benchmarking
• systemd Reference — unit files, drop-ins, timers, journalctl, socket activation, boot analysis
• OpenTelemetry Reference — SDK (Go/Python/Java/Node.js), Collector config, auto-instrumentation, debugging
• Bash Scripting Reference — set -euo pipefail, arrays, string manipulation, loops, functions, trap, retry patterns.
• Deno 2 Reference — TypeScript-first, permissions, KV store, npm compatibility, deployment
• Zustand Reference — create store, actions, selectors, persist, testing
• React Native Reference — core components, styles, navigation, APIs & Expo
• Jotai Reference — atoms, derived state, async atoms, storage & vs Zustand
• Hono Reference — routing, middleware, validation, Cloudflare Workers, RPC mode
• grep, sed & awk Reference — Recursive search, in-place edit, field processing, log analysis pipelines.
• vim / Neovim Reference — :wq, text objects (ci”/dat), :%s, macros, registers, splits, marks.
• tmux Reference — Sessions, panes (split/zoom), copy mode, .tmux.conf, SSH+tmux persistent sessions.
• Git Reference — rebase -i, cherry-pick, stash, reflog, bisect, worktree, force-with-lease.

🛠️ Developer Utilities & Calculators

• Regex Reference — Character classes, groups, lookaheads, named captures, flags, real-world patterns.
• JWT Token Inspector — Decode JSON Web Tokens client-side. Claim hints, expiry countdown, algorithm badge.
• Semver Range Tester — Test whether a version satisfies a range. ^, ~, >=, *, ||.
• Package Version Checker — Latest versions on npm, PyPI, crates.io, RubyGems with version gap detection.
• GitHub Release Tracker — Any public repo: releases with semver gaps and changelog rendering.
• Uptime SLA Calculator — 99.9% = how much downtime per year? Budget planner, industry grades.
• chmod Calculator — Build file permissions visually. Setuid/setgid/sticky bit explained.
• Linux Signal Reference — 31 signals with interactive kill command builder (PID/name/pgrep/port).
• HTTP Status Codes Reference — All 40+ codes explained with use cases and fix guidance.
• Well-Known Ports Reference — 60+ TCP/UDP ports. Sortable, searchable, category filter.
• NestJS Reference — Modules, controllers, services, guards, TypeORM, testing
• Apollo Client Reference — useQuery, useMutation, cache normalization, subscriptions, codegen

🔒 Security Scanners & Auditors

→ Security Tools Hub

• Kubernetes YAML Security Linter — Scan K8s Deployment/Pod YAML for 12 misconfigurations. A–F score with specific fixes.
• GitHub Actions Version Auditor — Check workflow uses: actions for outdated versions, mutable tag pinning, and unverified publishers.
• → Dependency Health Hub
• npm Package Health Checker — Find deprecated, abandoned, and single-maintainer risk packages in your package.json.
• package.json Batch Health Checker — check all npm deps in your package.json at once. A–F grades.
• requirements.txt Batch Health Checker — check all Python packages in requirements.txt at once. A–F grades.
• Maven Dependency Health Checker — check Maven dependencies for outdated versions, EOL status, and known CVEs (Java/Spring).
• Vulnerability Scanner — Paste requirements.txt or package-lock.json. Full CVE report from OSV.dev.
• K8s Deprecation Checker — Paste YAML, find APIs removed in K8s 1.33+. 99 deprecation rules.
• Dockerfile Security Linter — Scan Dockerfiles for security issues and best practice violations.
• Docker Compose Security Checker — Scan docker-compose.yml for socket mounts, privileged containers, hardcoded secrets, and DB ports on 0.0.0.0.
• PyPI Package Health Checker — Paste requirements.txt. Find deprecated, abandoned (5y+), and stale Python packages on PyPI.
• pyproject.toml Health Checker — check all Python deps in pyproject.toml. PEP 517 + Poetry. A–F grades.
• Rust Cargo.toml Health Checker — Find yanked crates, major version gaps, and abandoned dependencies in your Cargo.toml.
• Maven pom.xml Batch Health — check all Maven deps in your pom.xml at once. A–F grades.
• Gradle Batch Health Checker — check all Java deps in build.gradle. Groovy + Kotlin DSL. A–F grades.
• Cargo.toml Batch Health — check all Rust crates in your Cargo.toml at once. A–F grades.
• PHP Composer Package Health Checker — Check PHP Composer packages for abandonment and active maintenance.
• composer.json Batch Health Checker — check all PHP packages in composer.json at once. A–F grades via Packagist.
• NuGet Package Health Checker — Check NuGet (.NET) packages for deprecation and latest version.
• .csproj Batch Health Checker — check all NuGet packages in .csproj at once. A–F grades.
• Ruby Gems Health Checker — Check Ruby gems for latest version and download activity.
• Gemfile Batch Health Checker — check all Ruby gems in Gemfile.lock at once. A–F grades.
• Go Module Health Checker — Paste go.mod. Find major version gaps, pseudo-versions, and stale dependencies via the Go proxy.
• go.mod Batch Health Checker — check all Go modules in go.mod at once. A–F grades.
• GitHub Actions Security Checker — Scan workflows for supply chain attack vectors: pull_request_target misuse, missing permissions blocks, hardcoded secrets.
• Terraform Security Scanner — Check .tf files for hardcoded credentials, open ports, public S3 buckets, unencrypted storage, no deletion protection.
• HTTP Security Headers Analyzer — check any URL for HSTS, CSP, X-Frame-Options, and other security headers with an instant A–F grade.
• .env Security Scanner — detect exposed secrets, API keys, and tokens in .env files. Client-side.