Heimdall is the Matic Proof-of-Stake Verifier layer, which is responsible for check pointing a representation of the Plasma blocks to the main chain in our architecture.
Heimdall is built on top of the Tendermint consensus engine with changes to the signature scheme and various data structures. Most Tendermint Rest Api calls are available on Heimdall as well.
Here is a list of avaialable Rest Api calls on Tendermint: https://docs.tendermint.com/master/rpc/
Here are additional API calls specific to Matic: https://docs.matic.network/docs/contribute/heimdall/modules/governance/#rest-apis
In the following subchapters we will give some examples on how to use the Heimdall Rest Api