# Core

- [Catchup](/api/core/catchup.md): Get balls units between 2 main chain ids.
- [Get hash tree](/api/core/get-hash-tree.md): Get units between balls.
- [Get light props](/api/core/get-light-props.md): Get light client properties.
- [Post joint](/api/core/post-joint.md): Post an unit on Byteball network.
- [Pick divisible coins for amount](/api/core/pick-divisible-coins-for-amount.md): Get spendable inputs from a specific amount and asset.
- [Heartbeat](/api/core/heartbeat.md): Send heartbeat to notify the node you are awake.