How to Use Claude API: Complete Guide for Developers

Anthropic's Claude API gives developers access to one of the most capable large language models available. Whether you're building a coding assistant, a document summarizer, a customer support bot, or an autonomous agent, Claude's API is well-designed, straightforward to call, and powerful enough to handle genuinely complex tasks. This guide walks you through everything from getting your first API key to production-ready best practices. All examples are tested and working. Step 1: Get Your API Key Go to console.anthropic.com and create an account Navigate to API Keys in the left sidebar Click Create Key, give it a name, and copy the key immediately — you won't see it again Store your key securely. Never hardcode it in source files. Use environment variables: # Add to your shell profile or .env file export ANTHROPIC_API_KEY="sk-ant-..." For production, use a secrets manager (AWS Secrets Manager, HashiCorp Vault, Doppler, etc.) rather than environment variables baked into your deployment