What is an API Key?

An API key is a unique string of characters issued by a platform (like Google, Binance, OpenAI, etc.).

When your app sends a request, it includes this key to:

✅ Identify you

✅ Track usage

✅ Enforce permissions and limits

Think of it like:

🔐 A hotel key card (opens certain doors, not all)

🆔 A username without a password (simple but sensitive)

⚙️ How Is an API Key Used?

Most APIs require the key to be sent in:

HTTP headers (most secure)

Query parameters (less secure)

Example (conceptually):

App → sends request + API key

Server → verifies key → allows or denies access

🚨 Why API Keys Are Sensitive

If someone gets your API key, they can:

Use your account quota

Access your data

Trigger actions as if they were you

In some cases, cost you money

That’s why API keys should be treated like passwords.

🛡️ How to Use API Keys Securely (VERY IMPORTANT)
✅ Best Practices

🔒 Never share your API key publicly

Don’t post it on GitHub, forums, or screenshots

📦 Store keys in environment variables

Not hard-coded in source code

🔁 Rotate keys regularly

Generate new ones, revoke old ones

🧩 Limit permissions

Use read-only keys if write access isn’t needed

🌍 Restrict by IP or domain (if supported)

Prevent use from unknown locations

📊 Monitor usage

Sudden spikes = possible compromise

❌ What NOT to Do

🚫 Don’t send API keys in plain text emails

🚫 Don’t embed them in frontend JavaScript

🚫 Don’t reuse the same key everywhere

🧠 Quick Summary

API Key = digital identity for apps

Used to authenticate and control access

Powerful but dangerous if leaked

Security depends on how you store and manage it