Docs

Claude Code

Claude Code treats any Anthropic-format endpoint as a gateway. Two variables point it at Kunavo, the install is untouched, and every session bills per token from your balance instead of a subscription.

Two environment variables — ANTHROPIC_BASE_URL and ANTHROPIC_AUTH_TOKEN — move Claude Code onto pay-as-you-go without changing the install.

# One terminal session
export ANTHROPIC_BASE_URL=https://api.kunavo.com   # origin, no /v1
export ANTHROPIC_AUTH_TOKEN=sk-kn-...

claude

ANTHROPIC_BASE_URL is the origin. Claude Code appends /v1/messages itself — Anthropic's own verification snippet is curl "$ANTHROPIC_BASE_URL/v1/messages" — so a value ending in /v1 produces requests to /v1/v1/messages and a 404. This is the single most common setup failure; the ANTHROPIC_BASE_URL page covers the rest of them.

Use ANTHROPIC_AUTH_TOKEN, not ANTHROPIC_API_KEY. The two variables pick a header: AUTH_TOKEN sends Authorization: Bearer, API_KEY sends x-api-key. Kunavo authenticates on the bearer, and API_KEY additionally needs a one-time approval prompt in an interactive session before it takes effect.

Step by step

Create a key at /app/keys and copy it — it is shown once.
Export the two variables above for the session, or persist them in the env block of ~/.claude/settings.json: {"env":{"ANTHROPIC_BASE_URL":"https://api.kunavo.com","ANTHROPIC_AUTH_TOKEN":"sk-kn-..."}}. Anthropic's docs are explicit that the credential does not belong in a project's .claude/settings.json — that file gets committed.
Run claude and open the Status tab. A line naming Auth token confirms the gateway credential is active; a Login method line naming a claude.ai account means the variable was not picked up.
For the VS Code extension the variables go in claudeCode.environmentVariables in VS Code's own user settings — the extension checks credentials before it launches, so ~/.claude/settings.json reaches the spawned process but not that check.

Checked against Anthropic's “Connect Claude Code to an LLM gateway” on September 6, 2026. Third-party settings move; if a field name here no longer matches what you see, that page is the authority, not this one.

This is the short version. The full walkthrough — model choice, what a real session costs, and the failure modes — is in the Claude Code API key guide.

Verify before you debug the client

One request settles whether a failure is the endpoint, the key, or the configuration file. If this returns JSON, the same base URL and key work in Claude Code.

# Settles whether a failure is the endpoint, the key, or the client.
curl -sS https://api.kunavo.com/v1/messages \
  -H "Authorization: Bearer sk-kn-..." \
  -H "anthropic-version: 2023-06-01" \
  -H "content-type: application/json" \
  -d '{"model":"claude-sonnet-5","max_tokens":16,"messages":[{"role":"user","content":"ping"}]}'

Which model id to put in the field

Every text model is reachable as a model id — the live list is GET /v1/models, and the catalog with prices is on the models page. Rates are USD per 1M tokens, input / output.

Model id	Kunavo in / out	Where it fits in Claude Code
`claude-sonnet-5`	$2.00 / $10.00	the default working model — set with /model or ANTHROPIC_MODEL
`claude-opus-5`	$2.00 / $10.00	planning and architecture-level edits
`claude-haiku-4-5`	$0.40 / $2.00	the small/fast tier Claude Code uses for background work
`claude-opus-5-fast`	$7.00 / $35.00	same model, faster output, when latency is the constraint

Billing is per token from a prepaid balance with no monthly fee — see billing. On repeated context — which is most of what an editor or a chat client sends — prompt caching moves the bill more than the model choice does.

FAQ

How do I use Claude Code without a Claude subscription?

Set ANTHROPIC_BASE_URL to an Anthropic-format endpoint and ANTHROPIC_AUTH_TOKEN to that endpoint's key. Claude Code then authenticates to the endpoint instead of claude.ai, and usage is billed per token by whoever owns that credential rather than against a subscription plan. Anthropic documents this as gateway mode; the saved claude.ai login stays on disk, unused, and returns as soon as the variables are unset.

Should ANTHROPIC_BASE_URL include /v1?

No. Claude Code appends the route itself, so the variable is the origin — https://api.kunavo.com, not https://api.kunavo.com/v1. Anthropic's own verification command is curl "$ANTHROPIC_BASE_URL/v1/messages", which shows the concatenation directly. A base URL that already ends in /v1 sends requests to /v1/v1/messages and returns 404.

What is the difference between ANTHROPIC_AUTH_TOKEN and ANTHROPIC_API_KEY?

They put the credential in different HTTP headers: ANTHROPIC_AUTH_TOKEN sends Authorization: Bearer, ANTHROPIC_API_KEY sends x-api-key. A key in the wrong variable reaches the endpoint in a header it does not read and the request fails with 401. If a gateway's documentation says "bearer token", use ANTHROPIC_AUTH_TOKEN; if it says "API key" or "x-api-key", use ANTHROPIC_API_KEY.

Which Claude Code features stop working behind a custom base URL?

Remote Control and voice dictation both need a claude.ai identity and are unavailable while a gateway credential is set; Remote Control is additionally disabled whenever ANTHROPIC_BASE_URL points at a non-Anthropic host. The fast-mode availability check also goes directly to api.anthropic.com rather than following the base URL. Everything in the core loop — the agent, tools, subagents, MCP servers — runs on the Messages API and is unaffected.