Everything starts
with env.
In-depth guides on environment variables, Docker, and dev workflows — plus references for 100+ env vars and 42+ browser-based tools. Free, no signup.
Looking for .env? Read the complete guide to environment variable files.
Featured Guides
View all 84 guides →Guide
Google Maps API Key Gemini Abuse: Stop Surprise Bills
A leaked Google Maps API key can now call paid Gemini APIs and run up huge bills. Lock keys down with API restrictions and budgets — and recover after abuse.
Guide
The .env File: A Complete Guide to Environment Variables
Everything about .env files: syntax rules, parser quirks, language examples (Node, Python, Go, Docker), best practices, and the gotchas that bite.
Guide
Docker Compose Environment Variables: The Complete Guide
Use environment variables in Docker Compose: .env auto-load, env_file, --env-file, multi-environment patterns, substitution, and secrets.
Guide
.env File Syntax Rules: Quoting, Comments, Multiline
.env files have no formal spec, so quoting, inline comments, and multiline values parse differently in Node.js, Python, Ruby, Go, and Docker Compose.
Guide
AI Dark Factory Playbook: From Autocomplete to Autonomous
Six-level AI dark factory playbook from manual coding (Level 0) to fully autonomous code (Level 5). Concrete agentic-coding actions, real numbers, no hype.
Guide
Environment Variables in Rust: std::env, dotenvy & envy
Read env vars in Rust with std::env::var, load .env files via dotenvy, and deserialize typed config with envy. Plus the Rust 2024 unsafe-set_var change.
Recently updated
Guide
Securing Your Dev Environment for AI Coding Agents
Treat your AI coding agent as an untrusted intern: scope and expire API keys, lock down Docker egress, and assume prompt injection will exfiltrate secrets.
Guide
Build-Time vs Runtime Environment Variables
Build-time env vars are inlined into your bundle and frozen until you rebuild; runtime vars are read from process.env on each start. When to use each.
Guide
MCP Server Environment Variables & Secrets
How MCP servers receive secrets through the env block, why stdio servers do not inherit your shell, and scoping tokens so prompt injection cannot drain them.
Update
Claude Fable 5: Anthropic's Mythos-class model goes public
Claude Fable 5 tops SWE-Bench Pro at 80.3% and is the same model as Mythos 5 with safeguards on — not scaled down. Pricing, ranking, and access.
Guide
Vite Environment Variables: import.meta.env & Modes
Vite exposes only VITE_-prefixed vars on import.meta.env, statically replaced at build time. Covers .env modes, loadEnv, define, and undefined-var gotchas.
Guide
Bun Environment Variables: Bun.env & .env Auto-Load
Bun auto-loads .env, .env.{NODE_ENV}, and .env.local with no dotenv install. Bun.env vs process.env, $VAR expansion, --env-file, and build inlining gotchas.
send.env.dev — share .env files, API keys, and secrets, end-to-end encrypted
Stop pasting secrets into Slack, email, or chat. send.env.dev is end-to-end encrypted — only you and the recipient can ever read the secret. Not us, not your network, not anyone in between. Links self-destruct after the first read and expire within 24 hours.
- 🔐 Two-factor: URL key + passphrase
- 🔥 Self-destructs after one read
- ⏱️ Auto-expires
- 🇪🇺 EU data residency (GDPR)
Developer Tools
Browse all tools →.gitignore Generator
JSON Formatter & Validator
Prettify and validate instantly
Base64 Encode / Decode
Encode and decode text, URLs and files
IP Subnet Calculator
CIDR to IP range with visual breakdown
Client-side utilities — JSON formatter, Base64 encoder, UUID generator, and more.
References
Cursor
AI-native VS Code fork. Cursor 3 ships an Agents Window for parallel agents across local, worktrees, SSH, and cloud VMs. Composer 2 is the default model.
Windsurf
AI-powered IDE by Codeium with Cascade, an agentic LLM coding assistant that understands your full codebase.
GitHub Copilot
AI pair programmer by GitHub. LLM-powered autocomplete, chat, and agent mode integrated into VS Code and JetBrains.
Claude Code
Anthropic's CLI-based agentic LLM coding tool. Terminal-first AI assistant for complex multi-file tasks.
OpenCode
Open-source MIT-licensed terminal AI coding agent. BYO-model, MCP-native, signs in with your GitHub Copilot subscription.
Codeium
Free AI code completion tool. Fast LLM-powered autocomplete for 70+ languages across all major editors.
The AI Dark Factory Playbook
A 5-part series on AI-driven development — from manual coding to autonomous agents.
Start here · Primer
AI Dark Factory: Autonomous Coding Explained
AI dark factory: autonomous coding where agents write, test, and ship without human review. Coined by Dan Shapiro, Glowforge, January 2026.
Or jump straight to a part
Popular Comparisons
View all 11 comparisons →Comparison
Bun vs Deno vs Node.js: Which Runtime in 2026?
Compare Bun 1.3, Deno 2.7, and Node.js 24 LTS. Benchmarks for cold start, throughput, and install speed; how each handles .env files; and when to pick which.
Comparison
REST vs GraphQL: Which API Style Should You Use?
Compare REST and GraphQL APIs side by side. The trade-offs in performance, flexibility, caching, and developer experience, and how to choose.
Comparison
Docker vs Kubernetes: What's the Difference?
Understand the difference between Docker and Kubernetes. Docker builds and runs containers; Kubernetes orchestrates them at scale. Learn when to use each.
Comparison
npm vs yarn vs pnpm: Package Manager Comparison
Compare npm, yarn, and pnpm package managers. Benchmark install speed, disk usage, lockfile format, and monorepo support to pick the best one for your project.
Comparison
PostgreSQL vs MySQL: Which Database to Choose?
Compare PostgreSQL and MySQL databases. Analyze performance, features, JSON support, replication, and ecosystem to choose the right database for your project.
Comparison
Redis vs Memcached: In-Memory Caching Compared
Compare Redis and Memcached for caching. Evaluate data structures, persistence, clustering, and use cases to pick the right in-memory store.
Cheatsheets
View all 32 cheatsheets →OpenGraph Meta Tags Cheat Sheet — Sizes, Tags, Twitter Cards
Every OpenGraph and Twitter Card tag with recommended image sizes per platform (Facebook, LinkedIn, X, Slack, Discord) and a copyable HTML template.
HTTP Status Codes — Complete Quick Reference
Every HTTP status code explained with practical examples. 1xx through 5xx with when to use each code in your API.
CIDR Notation Cheat Sheet — Subnet Masks & Host Counts
Complete CIDR reference table: every prefix from /8 to /32 with subnet mask, total addresses, usable hosts, and common use cases.
YAML Syntax Cheat Sheet — Scalars, Collections & Gotchas
Quick reference for YAML syntax: strings, numbers, multiline values, sequences, mappings, anchors, aliases, and common gotchas like the Norway problem.
JSON Cheat Sheet — Syntax, Parsing & Common Mistakes
Quick reference for JSON syntax: data types, objects, arrays, JSON.parse/stringify, jq basics, and common mistakes like trailing commas and single quotes.
Cron Schedule Examples — 30+ Common Cron Expressions
Ready-to-use cron expressions for every common schedule: every 5 minutes, hourly, daily, weekly, monthly, and more.
Discounts
Browse all discounts →AWS Activate
Up to $100k in AWS credits for startups. Apply through the AWS Activate program with your startup details.
$2k+ creditsGoogle Cloud for Startups
Over $2,000 in Google Cloud credits for eligible startups. Apply through the Google for Startups program.
$150k creditsMicrosoft for Startups (Azure)
Up to $150k in Azure credits plus free access to Microsoft tools. Apply through the Microsoft for Startups Founders Hub.
$200 creditsDigitalOcean Hatch
$200 in infrastructure credits for startups. Apply through the Hatch startup program with your company details.
Free tierCloudflare
Generous free tier including CDN, DNS, DDoS protection, and Workers. Available to everyone, just sign up.
Free tierVercel
Free hobby tier with hosting, edge functions, and serverless deployments. Sign up with your personal account.
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