> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hypedexer.com/llms.txt
> Use this file to discover all available pages before exploring further.

# bbo

> Best Bid/Offer: top-of-book updates for one coin, emitted only when the top level changes

Subscribe with `{"method":"subscribe","subscription":{"type":"bbo","coin":"BTC"}}`. Initial top-of-book matches **`BboSnapshot`**; subsequent updates use **`BboUpdate`** and are only emitted when the top bid or ask changes in price, size, or order count.


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