AI Agent: API Key Guides

Getting API access to a large language model involves more than creating an account. Because each provider uses a different console, billing system, credential format, and security policy, the process varies. This document provides the steps to get, configure, and test API keys for five major AI platforms, which helps you avoid common issues when you start building.

Before you begin

Each provider requires a verified account and a payment method. You must have a credit or debit card ready. Because most platforms display your API key only once, you must store it securely.

What's Inside

Serial No.
Provider
Auth Method
Free Tier

1

OpenAI

API Key

No

2

Anthropic (Claude)

API Key

No

3

Google Gemini

API Key

Yes

Key differences at a glance

Provider
Credential format
Billing and access notes

OpenAI

Standard API key

Requires a minimum $5 credit purchase to process requests. The key is displayed only once.

Anthropic Claude

API key (uses the x-api-key header instead of a Bearer token)

Uses a prepaid credit model. Account approval might be required depending on your region.

Google Gemini

Standard API key

Offers a free tier. You can view your key multiple times in AI Studio. For production workloads, use Vertex AI.

Universal security rules

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  • Do not commit your API keys to a public repository.

  • Store your keys in environment variables or a secure secrets manager. Do not store them in plain text files.

  • Set spending limits, if the provider supports them, to prevent unexpected charges.

  • Rotate your keys periodically. If you suspect a leak, rotate them immediately.

  • Grant the minimum required permissions for each key.

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