Step-by-step guide

How to Use the Claude API: Complete Developer Guide

Get up and running with Anthropic's Claude API in under 5 minutes. This guide covers authentication, your first API call, streaming, and how to access Claude through LLMWise for automatic failover.

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1

Get your API key

You have two paths. Option A: sign up at console.anthropic.com, add billing, and generate a key. This gives you direct Claude access and nothing else. Option B: sign up at llmwise.ai and grab a single API key that gives you Claude plus 8 other models (GPT-5.2, Gemini 3 Flash, DeepSeek, etc.) through one endpoint. If you only need Claude and nothing else, go direct. If you want failover or access to multiple models, LLMWise saves you from managing separate keys.

2

Install the SDK

For direct Anthropic access, install the official SDK: `pip install anthropic` (Python) or `npm install @anthropic-ai/sdk` (JavaScript). For multi-model access through LLMWise, use the standard HTTP endpoint - no SDK required. Just point your requests to `https://llmwise.ai/api/v1/chat` with your LLMWise API key in the Authorization header.

3

Make your first chat completion

Here is a minimal Python example using the Anthropic SDK: ```python import anthropic client = anthropic.Anthropic(api_key="your-key") message = client.messages.create( model="claude-sonnet-4-5-20250514", max_tokens=1024, messages=[{"role": "user", "content": "Explain quantum computing in simple terms"}] ) print(message.content[0].text) ``` Through LLMWise, the equivalent call uses the same role/content message format - just change the endpoint and set `model` to `claude-sonnet-4.5`.

4

Add streaming for real-time responses

Streaming returns tokens as they are generated, cutting perceived latency dramatically. With the Anthropic SDK: ```python with client.messages.stream( model="claude-sonnet-4-5-20250514", max_tokens=1024, messages=[{"role": "user", "content": "Write a Python quicksort"}] ) as stream: for text in stream.text_stream: print(text, end="", flush=True) ``` LLMWise streams via Server-Sent Events with `data: {"delta": "...", "done": false}` chunks, which works with any SSE client in any language.

5

Handle errors and rate limits

Anthropic returns 429 when you hit rate limits and 529 during overload. Always implement exponential backoff with jitter. Common production issues: exceeding your RPM (requests per minute) tier, sending too many tokens in a burst, or hitting the daily spend cap. LLMWise pools rate limits across providers, so even if your Anthropic allocation is exhausted, requests can failover to another model automatically.

6

Add failover for production reliability

When Claude goes down - and every provider has outages - your app needs a fallback plan. With direct API access, you have to build retry logic and provider switching yourself. With LLMWise Mesh mode, failover is automatic: if Claude returns consecutive errors, requests route to GPT-5.2 or Gemini in sub-second time. When Claude recovers, the system detects it and starts routing traffic back. Your users never see a 500.

Evidence snapshot

How to Use the Claude API: Complete Developer Guide execution map

Operational checklist coverage for teams implementing this workflow in production.

Steps
6
ordered implementation actions
Takeaways
4
core principles to retain
FAQs
4
execution concerns answered
Read time
12 min
estimated skim time
Key takeaways
Direct Anthropic SDK works great for Claude-only use cases; LLMWise adds multi-model access and failover through a single key
Always use streaming in production - it reduces perceived latency from seconds to milliseconds for first token
Build error handling and rate limit retries from day one, or use LLMWise to handle them automatically
Failover is the difference between a 2am page and a seamless experience - plan for provider downtime

Common questions

How do I get started with the Claude API in Python?
Install the Anthropic SDK with `pip install anthropic`, create a client with your API key, and call `client.messages.create()` with a model name and messages array. You can have a working chat completion in under 10 lines of code.
What is the easiest way to start using the Claude API?
The fastest path is to sign up at llmwise.ai, grab your API key, and send a POST request to the chat endpoint with your prompt. No SDK installation required, and you get access to Claude plus 8 other models through the same key.
How does using Claude through LLMWise differ from the direct API?
The message format is identical (role/content). The key differences are: LLMWise adds automatic failover if Claude goes down, lets you switch models by changing one parameter, and gives you access to GPT-5.2, Gemini, and other models without managing extra API keys. You can also bring your own Anthropic key for direct billing.
How do I stream responses from the Claude API?
Using the Anthropic SDK, call `client.messages.stream()` and iterate over `stream.text_stream`. Through LLMWise, consume the Server-Sent Events stream where each chunk contains a `delta` field with the next piece of text. Both approaches deliver tokens in real time as Claude generates them.

Start on Auto, move up only when you need it

Free preview, Starter for the Auto lane, Teams for manual GPT, Claude, and Gemini Pro access. Add-on credits kick in after included plan tokens are used.

Start on cheap auto-routed models first, then move up only when your workload truly needs premium manual control.

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