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Anthropic’s Claude Code is an agentic AI coding assistant that runs in your terminal. By setting the ANTHROPIC_BASE_URL environment variable, you can route all Claude Code requests through Flatkey and pay Flatkey’s discounted rates on Claude model usage.

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Prerequisites

  • Claude Code installed: npm install -g @anthropic-ai/claude-code
  • A Flatkey account with an API key — get one here

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Configuration

Set these two environment variables:
To make the setting permanent, add them to your shell profile:
~/.zshrc
Set ANTHROPIC_BASE_URL to https://router.flatkey.ai — without a trailing /v1. The Claude Code CLI appends the correct path automatically.

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Configure with CC Switch

CC Switch is a third-party desktop configuration manager for coding assistants. You can also download it from the official GitHub repository.
  1. Open CC Switch and select Claude Code.
  2. Add a Custom Provider named Flatkey.
  3. Set the base URL to https://router.flatkey.ai without a trailing /v1.
  4. Enter your Flatkey API key (sk-fk-...) and activate the provider.
  5. Fully quit and reopen Claude Code so it reloads the provider settings.
  6. Send a small request, then confirm it in Usage Logs in the Flatkey Console.
If your CC Switch version does not include a Flatkey preset, use Custom Provider. CC Switch is not a Flatkey product.

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Running Claude Code

Use Claude Code exactly as you normally would:
or interactively:
All requests are routed to Flatkey and billed from your prepaid balance at discounted rates.

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Verifying the setup

Run a simple request and then check Usage Logs in your Flatkey Console. You should see the Claude request logged with its model ID, token counts, and cost.

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Savings estimate

Using Claude Sonnet (a popular choice for Claude Code) through Flatkey: On a typical Claude Code session of 50K input tokens, using Sonnet, that is:
  • Official: ~$0.15 per session
  • Flatkey: ~$0.08 per session
Heavy Claude Code users benefit most from the $200 top-up tier — the bonus credit effectively gives you an extra month of usage on top of the model discount.

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Troubleshooting