Claude Code (gateway)

Route Claude Code’s LLM calls through the Respan gateway for automatic logging, caching, and model switching. Only your RESPAN_API_KEY is needed.

Setup

Install Claude Code

$ npm install -g @anthropic-ai/claude-code

Set environment variables

Add to your shell profile (.bashrc, .zshrc, or PowerShell $PROFILE):

$ unset ANTHROPIC_AUTH_TOKEN
$ export ANTHROPIC_BASE_URL="https://api.respan.ai/api/anthropic/"
$ export ANTHROPIC_API_KEY="YOUR_RESPAN_API_KEY"

Use ANTHROPIC_API_KEY, not ANTHROPIC_AUTH_TOKEN, for Claude Code through the Respan Anthropic gateway. Claude prefers ANTHROPIC_AUTH_TOKEN when both are set.

Or use Claude Code settings (persistent)

Add to ~/.claude/settings.json for global config, or .claude/settings.local.json in your project for repo-local config:

1 {
2   "env": {
3     "ANTHROPIC_BASE_URL": "https://api.respan.ai/api/anthropic/",
4     "ANTHROPIC_API_KEY": "YOUR_RESPAN_API_KEY",
5     "ANTHROPIC_AUTH_TOKEN": ""
6   }
7 }

Setting ANTHROPIC_AUTH_TOKEN to an empty string clears any inherited token so Claude Code prefers ANTHROPIC_API_KEY. Run Claude Code as usual — all LLM calls will route through Respan.

The Anthropic gateway path is /api/anthropic/ (with trailing slash). For interactive Claude Code sessions, prefer shell env vars or ~/.claude/settings.json. If ANTHROPIC_AUTH_TOKEN is exported by your shell or terminal app, Claude may still prefer it, so unset or remove it first. On first interactive launch, Claude may prompt: Detected a custom API key in your environment. Choose Yes to use the Respan API key. If you skipped it earlier, run /config, search for custom, and enable Use custom API key. Non-interactive claude -p and claude --print use ANTHROPIC_API_KEY automatically.

Switch models

Once routed through the gateway, you can use any Claude model.

$ # In your shell
$ claude --model claude-sonnet-4-5-20250929
$ claude --model claude-3-5-haiku-20241022

See the full model list.

Pin requests to a specific provider

To route Claude Code to your Vertex AI throughput (or any other provider) without changing the model slug, set the X-Respan-Route-Provider header. Claude Code keeps using its standard slug and the gateway resolves the provider transparently:

$ export ANTHROPIC_CUSTOM_HEADERS="X-Respan-Route-Provider: vertex_ai"

For a fallback across providers (e.g. primary Vertex, fall back to Anthropic on failure), use fallback_models instead. See Reliability for fallback_models and load_balance_group, and Providers & models for inline router controls (models, exclude_models, exclude_providers).