How to Get Claude API? [2023]

The Claude API by Anthropic allows developers to integrate conversational AI into their applications. With natural language processing capabilities, Claude can understand requests, ask clarifying questions, and provide relevant responses.

In this comprehensive guide, we will cover everything you need to know about getting access to the Claude API and integrating it into your project.

Overview of Claude API

Claude is an AI assistant created by Anthropic, an AI safety startup. The goal of Claude is to provide helpful, harmless, and honest AI.

Some key capabilities of Claude include:

  • Natural language understanding – Claude can comprehend text and voice inputs to determine user intent. It supports over 100 languages.
  • Conversational ability – Claude can engage in dialogue, ask clarifying questions, and give contextual responses.
  • Knowledge base – Claude has access to a broad knowledge base to provide accurate information to users.
  • Custom trainability – Claude models can be fine-tuned with proprietary data to adapt Claude to specific use cases.

The Claude API allows developers to leverage these capabilities to create AI-powered applications. It provides REST endpoints to integrate Claude’s NLU and conversational functions into any software.

Some potential use cases of the Claude API include:

  • Chatbots and virtual assistants
  • Customer service automation
  • Intelligent search
  • Interactive content generation
  • Educational applications
  • Smart home devices

Benefits of Claude API

There are several advantages to using the Claude API for conversational AI:

Advanced NLU – Claude utilizes state-of-the-art natural language understanding models like GPT-3. This allows it to comprehend complex user inputs with higher accuracy.

Contextual responsesClaude can maintain context and have cohesive, multi-turn conversations instead of just responding turn-by-turn.

Customizable – Developers can fine-tune Claude models on custom data to tailor its knowledge and responses for specific use cases.

Ease of integration – Simple REST API with webhook support makes it easy to add Claude’s capabilities to any application.

ScalabilityClaude is designed to scale to high-volume production workloads with load balancing and horizontal scaling.

Cloud-basedClaude API is hosted on the cloud, so developers don’t have to worry about infrastructure management.

Continuous improvements – Anthropic continually trains Claude’s models on more data to expand its knowledge and improve accuracy.

Getting Access to Claude API

Anthropic is currently allowing limited access to the Claude API for qualifying applicants. Here is an overview of the process to get API access:

Apply for API Access

First, you need to apply for API access on Anthropic’s website. The application asks for some basic details like name, email, company name, use case, and expected monthly usage.

Anthropic reviews each application to ensure legitimate use cases that are aligned with Claude’s purpose as helpful, harmless, and honest AI.

Get Approval

If your application is approved, you will receive an email from Anthropic with instructions for setting up API access and getting API keys.

The approval process may take some time as Anthropic is currently restricting Claude’s availability due to its limited training data. You may have to wait a few weeks or months after applying to get access.

Accept Terms of Use

Before using the API, you will need to accept Anthropic’s Terms of Use which outline appropriate uses of Claude and limits on Claude’s capabilities. This is to prevent misuse.

You agree not to have Claude perform certain unsafe or unethical actions, spread misinformation, or unfairly mimic specific individuals.

Configure API Keys

Once approved, you will receive a dashboard to manage API keys for your application. The keys authenticate your API requests to Claude servers.

You can generate multiple keys with different quotas and restrictions as needed for each application or environment like development, staging, production.

Technical Overview of API

Now let’s dive into the technical details of interacting with the Claude API.


The API endpoint you will make requests to is:

All endpoints in the documentation will stem from this base URL.


The Claude API supports two main methods:


The /query endpoint is used for sending a text query to Claude and receiving its response. It allows you to integrate Claude’s NLU and conversational capabilities.

Example input:

Example output:


The /moderation endpoint can be used to screen text for inappropriate content. Claude will flag if the input contains toxic, hateful, or unsafe language.

Example input:

Example output:

This allows you to moderate UGC (user generated content) and enforce positive discussions.

Request Format

Requests are sent as JSON payload with the following structure:

  • user – Unique ID to track user sessions
  • messages – Array of messages with:
  • roleuser or assistant
  • content – Object with text content
  • For /moderation, a simple text parameter with the input text

Response Format

Responses are returned as JSON with:

  • bot name
  • messages array similar to the request
  • For /moderation, categories object with toxicity scores

Error Handling

The API returns standard HTTP status codes like:

  • 200 OK for success
  • 400 Bad Request for malformed requests
  • 403 Forbidden for invalid API key
  • 500 Internal Server Error for server issues

The body will contain an error message with details to help debug the issue.

Rate Limiting

To prevent abuse, the Claude API enforces rate limits on requests per API key. The exact limits depend on your pricing plan.

If exceeded, the API will return a 429 Too Many Requests error with the retry time in the header:


To use the Claude API, you need to authenticate each request with an API key.

There are two types of API keys:

Master API Key

This key is used to manage all other keys in your project. It provides full access to your Claude dashboard and configuration settings.

The master key should be kept secure on the server side and not exposed in client applications.

Subscriber Key

This key is used for making /query and /moderation requests from your application.

Distribute subscriber keys to each client or environment that needs to access the Claude API. Set appropriate quotas on each key.

Passing API Key

The API key should be passed in the request headers as:

Do not expose the key in code or URLs to keep it private.

Trying the API

Anthropic provides a sandbox endpoint for experimenting with the Claude API before production integration.

The sandbox URL is:

It requires passing a temporary API key provided in the Claude dashboard.

The sandbox has mock responses and limits. But it allows you to validate integration before Launch.

Client Libraries

While the raw JSON API is quite simple, Anthropic also provides SDKs in various languages to make integration easier:

  • Python
  • JavaScript
  • Java
  • C#
  • Ruby
  • PHP
  • Go

These libraries wrap the API calls and authentication for you. They also feature helper methods, retry logic, etc.

For example:

Use Cases and Examples

Let’s look at some examples of how you can use the Claude API:


Build a conversational chatbot by passing user messages to /query and displaying Claude’s responses:

Use session IDs to maintain context across multiple turns.

Search Engine

Classify search queries into intent categories using /moderation:

Content Moderator

Screen user posts and comments with /moderation to flag toxic language:


Answer frequently asked questions by matching user input to canned responses:

Data Analysis

Extract insights from text datasets using Claude’s classification capabilities:

Pricing and Plans

Anthropic offers tiered pricing plans for the Claude API depending on your expected monthly usage:

Free Plan

Lets you try the API with limited queries for free. Good for small projects.

Basic Plan

Offers up to 50,000 queries for $49/month. Best for early product stages.

Plus Plan

Allows 500,000 queries for $499/month. Scales for growth.

Business Plan

Custom pricing for very high volume usage like chatbots. Contact Anthropic sales.

Volume discounts are available if you prepay for usage.

The pricing is based on the number of /query requests. /moderation has lower limits.


The Claude API provides a powerful conversational AI assistant to integrate into your applications. With natural language capabilities and customizable knowledge, it can understand text, engage in dialogue, and provide helpful responses.

Key takeaways:

  • Apply for access by submitting a use case to Anthropic
  • Integrate using simple REST API or client libraries
  • Pass API keys for authentication and manage keys securely
  • Try the sandbox before launching to production
  • Choose pricing plan based on expected monthly usage

By leveraging Claude’s AI, you can create intelligent and interactive products to delight your users. The API abstracts away the complexity of conversational AI.

Sign up and get started with Anthropic today to take advantage of Claude’s helpful, harmless, and honest AI.


What is the Claude API?

The Claude API is developed by Anthropic to allow integrating conversational AI capabilities into applications. It lets you make requests to Claude’s natural language processing models to understand text, have dialogues, and generate responses.

How do I get access to the Claude API?

You need to apply on Anthropic’s website with your use case and expected usage. If approved, you receive API keys to start making requests. Access is currently limited while in beta.

What are the charges for using Claude API?

Anthropic has tiered pricing plans like Free, Basic, Plus, and Business based on the number of requests per month. There are volume discounts available.

What are some use cases of Claude API?

Some examples are chatbots, search engines, content moderation, FAQ bots, data analytics, virtual assistants, and more. Any application that needs text understanding or dialog can benefit.

Which languages does Claude API support?

Claude has natural language understanding capabilities for over 100 languages including English, Spanish, French, Chinese, Hindi, Arabic, and more.

How do I authenticate my API requests?

You need to pass an API key in the authorization header for each request. Subscribe keys are for your apps, while master keys manage your overall access.

Is there a limit on the number of requests?

Yes, Claude has rate limiting to prevent abuse. Limits depend on your pricing plan, but you may get blocked if exceeding quotas.

Is there a sandbox available for testing?

Yes, Claude provides a sandbox URL to try out the API with fake responses before going to production.

Do you provide client libraries?

Yes, we offer SDKs for Python, JavaScript, Java, C#, Ruby, PHP, Go, and other languages to simplify using the API.

Where can I find docs and support?

See the Claude API documentation site for getting started guides, references, and support forums. You can also email their support team.

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