Claude Third-Party Apps: Complete List, How They Work, and Billing Explained

Claude is not limited to claude.ai. Dozens of third-party apps connect to Claude through Anthropic's OAuth system, letting you use Claude's models inside code editors, terminal tools, browser extensions, and automation platforms. This guide covers which apps qualify as third-party, how they connect, what the billing changes mean, and how to keep everything running.

What Counts as a Claude Third-Party App

A Claude third-party app is any tool that accesses Claude's models through your Claude account (via OAuth sign-in) rather than through a direct API key. The distinction matters because Anthropic now bills these two paths differently.

If the app asks you to "Sign in with Claude" or redirects you to claude.ai to authorize access, it is a third-party app. If the app asks you to paste an API key, it uses API billing instead.

Complete List of Claude Third-Party Apps

Here is every major app and tool that connects to Claude as a third-party app, organized by category.

Code Editors and IDEs

Browser and Productivity Tools

Automation and Agent Platforms

How Third-Party App Authentication Works

When you connect a third-party app to Claude, the app redirects you to claude.ai for authorization. This is standard OAuth: you sign in, grant the app permission, and the app receives a token it uses to make requests on your behalf. You never share your password with the app.

The OAuth flow works like this:

1. You open the third-party app and choose "Sign in with Claude"
2. The app redirects your browser to claude.ai
3. You sign in (if not already) and approve the app's access request
4. Claude sends a token back to the app
5. The app uses that token for all Claude requests going forward

You can revoke access for any third-party app at claude.ai/settings under the connected applications section.

How Billing Works for Third-Party Apps

Anthropic changed third-party app billing in early 2026. Previously, third-party apps drew from your plan's included usage. Now, third-party app requests draw from a separate prepaid balance called "extra usage credits."

The Three Billing Pools

These pools are completely separate. You cannot transfer balance between them.

Starter Credits

When Anthropic made this change, they gave existing accounts a one-time starter credit to ease the transition:

What Happens When Credits Run Out

Once your extra usage balance reaches zero, all third-party apps stop working. You will see messages like "LLM request rejected" or "you're out of extra usage." Your claude.ai and mobile app access is unaffected.

To keep going, add more credits at claude.ai/settings/usage. You can configure auto-reload to refill your balance automatically when it drops below a threshold.

Managing Usage Across Multiple Third-Party Apps

If you use several third-party apps (say Cursor for coding and Claude Code for terminal tasks), they all draw from the same extra usage credit pool. There is no way to allocate credits per app.

Tips for managing usage across apps:

• Check your balance regularly at claude.ai/settings/usage
• Set up auto-reload so you never run out mid-session
• Use Sonnet for routine tasks instead of Opus, since Opus costs significantly more per request
• Close apps you are not actively using to avoid background requests that drain credits
• Review connected apps in your Claude settings and revoke access for tools you no longer use

Troubleshooting Common Issues

"LLM Request Rejected" After the Billing Change

This means your extra usage credits are at zero. Go to claude.ai/settings/usage and add credits or claim your starter credit if you have not already.

Third-Party App Cannot Connect

Check that you are signing in with the correct Claude account. If you have multiple accounts (personal and work), the app connects to whichever account you authenticate with. The extra usage balance is tied to that specific account.

Organization Account Shows Rejection for All Team Members

On Team and Enterprise plans, a workspace administrator must claim the starter credit before team members can use it. Ask your admin to visit claude.ai/settings/usage and accept the organization credit.

App Works With API Key but Not OAuth

Some apps support both authentication methods. If OAuth is not working (credits exhausted), switching to an API key is an option, but it bills differently. API billing is pay-per-token and does not use your extra usage balance.

Which Connection Method Should You Use

If your tool supports both OAuth and API keys, here is how to choose:

For most individual developers using Cursor or Claude Code, OAuth is simpler and the prepaid credit model makes costs predictable. For production applications or high-volume automated workflows, API keys give you more granular control over spending and rate limits.

Fazm is an open source macOS AI agent that starts with free built-in credits, so you can try it without worrying about extra usage. When you are ready, connect your personal Claude Pro or Max subscription and keep going. Open source on GitHub.