# Model

The **Model** page chooses the model that answers the chatbot's visitors. Its
list holds the models of every provider with a stored
[API key](/docs/ai/settings/api-keys.md), and your
[custom models](/docs/ai/settings/custom-models.md), with a search field. The
editor proposes OpenAI's `gpt-4o-mini` for a new chatbot; save the page to keep
the model you choose.

Choose with the chatbot's job in mind. A small, fast model answers simple
questions about your content well and cheaply, since every visitor message is
billed by the provider along with the chatbot's whole instruction. A larger
model is worth it for questions that need reasoning across a lot of content.
[File search](/docs/ai/chatbots/data.md#synchronizing-to-openai-file-search)
needs an OpenAI model.

A chatbot that uses a custom model reaches it as the chatbot's author, so the
model and its API key have to belong to the user who created the chatbot.

## Limits on visitor requests

Visitors' requests are checked before they reach the provider. A request must
come from a chatbot rendered on the site, and a conversation larger than
256 KiB, as JSON, is refused as too large. The `sleekAi/chatbot/maxRequestBytes`
filter changes that limit; see the [hooks reference](/docs/ai/reference/hooks.md).

A visitor can send one chatbot 30 messages in five minutes; further messages
are refused until the five minutes are over, and the chatbot shows the
reason. Visitors are told apart by their IP address, so on a site behind a
proxy that does not pass the visitor's address on, all visitors share one
limit. The `sleekAi/chatbot/rateLimit` filter changes the number, per
chatbot, and `0` removes the limit. Administrators are not limited.

All of a chatbot's visitors together can send it 200 messages an hour and
1,000 a day, which caps what a public chatbot can cost however many visitors,
or addresses, its messages come from. The hour starts on the hour and the day
at midnight UTC; once either budget is used up, the chatbot tells every visitor
to try again later until that window ends. A message the budget refuses does
not count against it. The `sleekAi/chatbot/budget` filter changes either
number, per chatbot, and `0` removes that budget; administrators' messages are
not counted. With a persistent object cache the budget is counted atomically;
without one, messages that arrive at the same moment can pass it by a few.