env-seal

The strictest, zero-dependency environment validator.

Support for Node.js, Deno, Bun, and Edge Runtimes.

Why Env-Seal?

Most environment libraries are either too loose (runtime crashes) or too heavy (dependencies). env-seal is designed for production-grade reliability.

• Zero Dependencies: Keeps your node_modules clean.
• Strict Typing: TypeScript first. Returns a strictly typed configuration object.
• Secure: Secrets are properly redacted from logs (console.log) and output (JSON.stringify).
• Granular Validation: Chainable rules for Email, URL, Min/Max, and Regex.
• Native .env Support: Built-in zero-dependency .env parser (optional).
• Auto-Docs: Generate markdown tables for your schema automatically.

Installation

npm install env-seal
# or
pnpm add env-seal
# or
bun add env-seal
# or
deno add npm:env-seal

Quick Start

import { define, e } from 'env-seal';

// 1. Define your schema
const config = define({
  PORT: e.number().default(3000),
  NODE_ENV: e.string().default('development'),
  API_KEY: e.string().secret(), // Required + Hidden from logs
  CONTACT_EMAIL: e.string().email(),
  SITE_URL: e.string().url(),
}, { 
  loadDotEnv: true // Optional: Load .env file
});

// 2. Use it! (Type-safe)
console.log(`Server running on port ${config.PORT}`);
// config.API_KEY is available here, but hidden if you log the whole object.

Features

🛡️ Granular Validation

Validate your inputs with precise rules:

| Rule | Description | Example | | :--- | :--- | :--- | | .email() | Validates email format | e.string().email() | | .url() | Validates URL format | e.string().url() | | .min(n) | Min value (number) or length (string) | e.number().min(10) | | .max(n) | Max value (number) or length (string) | e.string().max(100) | | .regex(re) | Custom pattern matching | e.string().regex(/^[a-z]+$/) |

🔒 Security & Redaction

Mark sensitive variables with .secret().

• Accessible in code: config.API_KEY works fine.
• Hidden in logs: console.log(config) shows [REDACTED].
• Hidden in JSON: JSON.stringify(config) shows [REDACTED].

📄 Documentation Generator

Generate a Markdown table of your environment variables for your README.md or llms.txt.

import { generateMarkdown } from 'env-seal';

const md = generateMarkdown(schema);
console.log(md);

Output:

| Variable | Type | Required | Default | Rules | | :--- | :--- | :--- | :--- | :--- | | PORT | number | No | 3000 | - | | API_KEY | string | Yes | [REDACTED] | (Secret) |

Example Schema Docs

Run generateMarkdown(schema) to automatically produce tables like this:

Environment Variables

| Variable | Type | Required | Default | Rules | | :--- | :--- | :--- | :--- | :--- | | APP_NAME | string | No | My App | - | | PORT | number | No | 3000 | - | | DATABASE_URL | string | Yes | - | (Secret) | | ADMIN_EMAIL | string | Yes | - | Email | | MAX_CONNECTIONS | number | Yes | - | Min: 1, Max: 100 |

License

MIT