Tiller, Helm's server-side component, serves gRPC natively. This provides a simple transcoding proxy that converts JSON to gRPC, and exposes a number of endpoints. It also adds an authentication layer.
Status of the server: GET /
List all releases: GET /v1/releases
Install a Chart: POST /v1/releases
Get a release by name: GET /v1/releases/{RELEASE_NAME}
Upgrade a Release: POST /v1/releases/{RELEASE_NAME}
Get release history: GET /v1/releases/{RELEASE_NAME}/history
Rollback to a previous release: POST /v1/releases/{RELEASE_NAME}/history/{VERSION}
Delete a release: DELETE /v1/releases/{RELEASE_NAME}