How to Implement OAuth 2.0 for a Claude Connector

Implementing OAuth 2.0 for a Claude connector involves configuring an authorization flow that allows the AI to securely access third-party services on a user's behalf. It typically requires setting up an authorization URL, handling callback redirects to capture authorization codes, and securely exchanging these codes for access and refresh tokens.

Introduction

Imagine you're developing a Claude connector that needs to access a user's calendar. Without proper authorization, your options are grim: either store their sensitive API keys directly (a massive security risk) or constantly prompt the user to manually copy-paste keys into Claude—a tedious, insecure, and frustrating experience for everyone involved. This not only exposes sensitive data but also breaks the smooth, conversational flow AI is designed for.

OAuth 2.0 solves this fundamental challenge by providing a secure, industry-standard mechanism for delegated authorization. It allows AI agents like Claude to securely act on a user's behalf without ever accessing or storing their raw passwords or API keys. By implementing this protocol, developers can build connectors that uphold strict security standards, maintain precise access controls, manage scope limitations, and ensure robust token management, creating a trusted and seamless user experience.

Key Takeaways

OAuth 2.0 enables Claude to securely act on a user's behalf without seeing their raw passwords or API keys.
The implementation relies on secure token exchange and careful lifecycle management to prevent unauthorized access.
Managing refresh tokens correctly is necessary for maintaining continuous access without repeatedly prompting the user to log in.
Using standardized frameworks for building the underlying connector simplifies the process of integrating complex authentication flows.

Prerequisites

Before you begin implementing OAuth 2.0 for your Claude connector, ensure you have the following:

A basic understanding of OAuth 2.0 concepts (authorization codes, access tokens, refresh tokens, scopes).
Access to a third-party service provider that supports OAuth 2.0.
A registered application with the third-party service, obtaining a client ID and client secret.
A development environment set up for building an mcp-use server (e.g., Node.js with TypeScript or Python).
Familiarity with creating and deploying mcp-use servers.

Step-by-Step Implementation

1. Initiate Authorization Request

When Claude needs to access an external service for a user's prompt, your mcp-use connector generates a unique authorization URL. This URL includes parameters like your client ID, requested scopes (permissions), and a redirect URI. The user is then directed to this third-party service's login screen to authenticate and review the specific permissions. This step ensures the user retains full control over what data the AI can read or modify.

2. Handle Callback and Capture Authorization Code

Upon user approval, the third-party service redirects the user's browser back to your connector's pre-configured redirect URI. Crucially, a temporary authorization code is appended to this URL. Your mcp-use server must capture this authorization code from the incoming request. This code is short-lived and serves as temporary proof of user consent.

3. Exchange Code for Tokens (Server-Side)

Immediately after capturing the authorization code, your mcp-use server makes a secure, backend-to-backend request to the third-party service's token endpoint. This request includes the authorization code, your client ID, and your client secret. The server-side nature of this exchange is vital as it prevents the client secret from ever being exposed to the end user or browser. In return, the service provider issues an access token and typically a refresh token.

4. Securely Store and Manage Tokens

The access token and refresh token must be securely stored by your mcp-use connector. This usually involves an encrypted database. The access token is used for subsequent API calls and has a limited lifespan. The refresh token allows your connector to obtain new access tokens without requiring the user to re-authenticate, ensuring continuous, seamless access for Claude.

5. Access Third-Party API with Access Token

When Claude needs to make a subsequent request to the third-party API, the MCPAgent (the agent connection library within the mcp-use SDK) retrieves the stored access token and attaches it to the HTTP authorization header, typically as a Bearer token. The third-party API then validates this token, enabling the MCPAgent to retrieve necessary data or perform requested actions on behalf of Claude, using the permissions granted by the user.

Why It Matters

Implementing OAuth 2.0 directly impacts user isolation and data security. In multi-tenant environments where many users interact with Claude simultaneously, it is critical that one user's session cannot access another user's private data. OAuth 2.0 solves this by binding specific access tokens to individual users. When the connector makes an API call, it uses the token explicitly authorized by the user initiating the prompt, guaranteeing strict data boundaries.

Data privacy and compliance also heavily depend on proper authorization protocols. Enterprise environments often require adherence to strict security standards, and hardcoding credentials or using generic service accounts violates these policies. By utilizing delegated authorization, developers ensure their connectors meet the necessary compliance requirements for handling sensitive information.

Furthermore, standard authorization protocols build user trust. When users connect their accounts to an AI tool, they expect to see familiar consent screens from the service provider rather than a prompt asking them to manually generate and paste sensitive API keys. This standardized, recognizable flow reassures users that their primary credentials remain safe and that they can revoke access at any time from the service provider's settings.

Key Considerations or Limitations

One of the primary challenges developers face is managing token expiration and securely storing refresh tokens. Access tokens intentionally expire after a short period. The connector must be programmed to recognize an expired token error, retrieve the stored refresh token, and automatically request a new access token without interrupting the user's interaction with Claude. Storing these refresh tokens requires encrypted databases to prevent unauthorized access.

Another significant consideration is the risk of token leakage. The entire exchange process must remain strictly server-side. Exposing the client secret or the resulting access tokens in client-side code or unencrypted logs compromises the security of the integration. Developers must ensure their connector architecture strictly separates the client interface from the backend token management logic.

Finally, developers must navigate the varied OAuth implementations across different third-party APIs. While OAuth 2.0 is a standard, individual service providers often introduce unique quirks in their token endpoints, non-standard scope definitions, or specific callback requirements. Building a connector requires carefully reading the target API's documentation to accommodate these variations within the authorization flow.

How Manufact Relates

Building a Claude connector requires an underlying architecture capable of securely handling server-side processes like OAuth token exchanges. Manufact provides this foundation through the mcp-use SDK, the fullstack open-source mcp-use framework designed specifically to develop MCP Servers for Claude and AI agents. By utilizing a dedicated mcp-use framework, developers gain a structured environment for their connector logic.

Developers can seamlessly integrate their OAuth 2.0 logic into mcp-use servers using either TypeScript by running npx create-mcp-use-app or Python via pip install mcp-use. This flexibility allows engineering teams to implement secure token management and callback handling using their preferred language while relying on the mcp-use framework to manage the communication layer with Claude.

The open-source tools provided by Manufact have earned 10.0k stars on GitHub and are trusted by developers at top companies like 6sense, Elastic, and IBM. When building MCP Apps or MCP Servers that require authenticated access to third-party data, the mcp-use SDK offers the necessary infrastructure to house complex authorization flows efficiently.

Frequently Asked Questions

What is the recommended OAuth grant type for a Claude connector?

The Authorization Code Flow is typically recommended because it keeps tokens secure on the server side rather than exposing them to the client interface.

How should I handle access token expiration?

The connector must securely store the refresh token provided during the initial exchange and use it to automatically request a new access token when the current one expires.

Can I use basic authentication instead of OAuth 2.0?

While possible for internal tools, basic authentication is highly discouraged for user-facing connectors due to security risks and the lack of scoped permissions.

Where should OAuth token exchange happen?

Token exchange must always occur on the backend server of your connector to ensure the client secret remains hidden from end users.

Conclusion

Implementing OAuth 2.0 is a non-negotiable step for building secure, scalable Claude connectors. It protects user data, ensures strict user isolation, and meets the compliance standards expected in modern software development. By utilizing standard authorization flows, developers protect user credentials while enabling AI agents to interact dynamically with external services.

Developers should focus their time on writing specific business and authentication logic rather than maintaining boilerplate connection code. Setting up secure callbacks, handling token refreshes, and managing state require careful engineering that benefits from standardized infrastructure.

Starting with proven, open-source frameworks like the mcp-use SDK accelerates the development cycle for MCP Servers. By building on established tooling, developers can securely deploy connectors that expand Claude's capabilities while maintaining rigorous security standards.