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Signing in: subscriptions and keys

Use your Claude, ChatGPT, Copilot or xAI subscription, or API keys, and see what is available right now.

functai needs a way to pay for each call: an API key from a provider, or a subscription you already have (Claude Pro/Max, ChatGPT Plus/Pro, GitHub Copilot, xAI). Sign in once; every later session uses it.

API keys

Set the provider's variable in your environment, and name a model:

export OPENAI_API_KEY=sk-...
export ANTHROPIC_API_KEY=sk-ant-...

functai.configure(lm="gpt-4.1-mini")

Or save a key once, so you don't need the variable:

functai.login("openai")                 # asks for the key
functai.login("groq", key="gsk-...")

Subscriptions

functai.login("claude")       # Claude Pro/Max
functai.login("chatgpt")      # ChatGPT Plus/Pro (the Codex backend)
functai.login("copilot")      # GitHub Copilot
functai.login("grok")         # xAI
functai.login("openrouter")   # approve in the browser; OpenRouter makes a key
functai.login()               # asks which

A browser opens when the machine has a screen; over SSH the link (or a device code) is printed for you to open anywhere. Then name the model with the account's prefix:

functai.configure(lm="claude:claude-sonnet-4-5")
functai.configure(lm="chatgpt:gpt-5.5")
functai.configure(lm="copilot:gpt-4.1")

A Claude Code or Codex CLI already signed in on this machine is used as is: no new login, nothing copied. functai.login("claude") just records that choice.

Whether a provider allows its subscription to be used this way, and how it bills it, is the provider's decision. Some sign-ins (GitHub Copilot, Kimi Code, the Claude and ChatGPT browser logins) are not yet certified by lm15; functai says so before starting.

What can I use right now?

functai.logins() lists everything available on this machine, and a model to try with each. It only reads files and environment variables:

provider        how                            status                            try
──────────────  ─────────────────────────────  ────────────────────────────────  ────────────────────────
Claude          saved login                    ready until 2026-09-26 19:02 UTC  claude:claude-sonnet-4-5
GitHub Copilot  saved login                    ready until 2026-09-27 11:02 UTC  copilot:gpt-4.1
ChatGPT         Codex CLI                      found                             chatgpt:gpt-5.5
openai          environment ($OPENAI_API_KEY)  found                             gpt-4.1-mini

Which credential a call uses

For each call, the first of these that exists:

  1. an explicit api_key= (in @ai, using or configure);
  2. the saved login or key for that provider;
  3. the environment variable, or a CLI login found on the machine.

So a saved key beats the same provider's environment variable.

When a login runs out

Logins renew themselves. One that expired and can't renew raises functai.LoginRequired, with the command to type (functai.login('claude')). functai never switches to a paid key on its own. A missing key raises the same error, naming the variable to set.

  • functai.login("claude") when you are already signed in says so and does nothing; again=True signs in again.
  • functai.logout("claude") forgets the saved login. An environment key or CLI login for that provider is used again afterwards (except xAI, which lm15 blocks on purpose).

Where logins are kept

In lm15's credentials file, ~/.config/lm15/credentials.json (or $LM15_CREDENTIALS_PATH), shared with every tool built on lm15. configure(auth="path/to/file.json") uses another file; configure(auth=False) uses none.