Setting Up Claude Code

What to Use

For Claude Code, the primary Nexus endpoint is:

• POST /v1/messages

Token counting is also supported:

• POST /v1/messages/count_tokens

Environment Variables

The simplest option:

export ANTHROPIC_BASE_URL="https://api.nexus-hub.ru"
export ANTHROPIC_AUTH_TOKEN="your_nexus_key"

After that, Claude Code will send requests through Nexus.

Pick the model only from the GET /v1/models response for your key.

Direct HTTP Call

For Claude-compatible integrations, you can also call the API directly:

curl https://api.nexus-hub.ru/v1/messages \
  -H "x-api-key: YOUR_NEXUS_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "Content-Type: application/json" \
  -d '{"model":"claude-sonnet-4-6","max_tokens":128,"messages":[{"role":"user","content":"ping"}]}'

Authorization: Bearer <key> and api-key: <key> are also supported.

Recommended Model

A good default option:

• claude-sonnet-4-6

If your key has access to other Claude models, they will appear in GET /v1/models.

What to Check If It Does Not Work

1. There are no old ANTHROPIC_* variables in the environment.
2. The key was copied without extra spaces.
3. The model appears in GET /v1/models.
4. The base URL is https://api.nexus-hub.ru, without /v1.