API Key Generator Free Online Tool 2026

Last updated March 22, 2026

What Is an API Key?

An API key is a unique identifier used to authenticate requests to an API. Unlike OAuth tokens, API keys are simple strings — typically 32–64 random characters — that are included in requests via a header, query parameter, or request body. They identify the calling application and are used for rate limiting, usage tracking, and access control.

API Key Formats

Generating Secure API Keys

// Browser: cryptographically secure random bytes
function generateApiKey(length = 32) {
  const bytes = new Uint8Array(length);
  crypto.getRandomValues(bytes);
  return Array.from(bytes, b => b.toString(16).padStart(2, '0')).join('');
}

// With prefix (like Stripe's sk_live_ format)
function generatePrefixedKey(prefix = 'key', length = 32) {
  const random = generateApiKey(length);
  return `${prefix}_${random}`;
}

// Node.js
import { randomBytes } from 'crypto';
const apiKey = randomBytes(32).toString('hex');
const base64Key = randomBytes(32).toString('base64url');

console.log(generateApiKey());
// → 'a3f8c2d1e4b5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1'

API Key Security Best Practices

• Never commit API keys to version control — use environment variables.
• Use different keys for development and production environments.
• Implement key rotation — allow multiple active keys during transition.
• Store keys hashed (SHA-256) in the database, not in plaintext.
• Set expiration dates and scope restrictions on keys.
• Log all API key usage for audit trails.