Get an Anthropic (Claude) API key

Anthropic builds the Claude family of models. You need an Anthropic Console account (separate from a Claude.ai chat subscription) to get an API key.

Create your key

1. 1
   Sign up at console.anthropic.com

   Go to console.anthropic.com and click Sign up. You can use email + password or continue with Google. Verify your email when prompted.
2. 2
   Add billing

   Navigate to Settings > Billing and add a credit card. Anthropic uses prepaid credits -- you load a balance and draw it down with usage. New accounts may receive a small starter credit (around $5) for testing, but a payment method is typically required before calls work.
3. 3
   Create an API key

   Go to Settings > API Keys (direct link: console.anthropic.com/settings/keys). Click Create Key, give it a name like "Prompt Assay", and click Create Key again.
4. 4
   Copy immediately

   The key is displayed only once. Copy it now and store it somewhere safe. If you lose it, you must create a new one. The key starts with sk-ant-api03-.

Add it to Prompt Assay

Open Workspace Settings > Provider Keys, select Anthropic, paste the key, click Test, then Save. See Adding and testing a provider key for the full walkthrough.

Good to know

• A Claude Pro / Max chat subscription is completely separate from API access. The subscription does not include API credits, and API credits do not give you a chat subscription.
• Set a monthly spend limit in the Console to avoid surprise bills. The default may be low, which can cause unexpected rate-limit errors on busy workspaces.
• New accounts start on the lowest rate-limit tier. Your tier increases automatically as cumulative spend grows.