Cloud computing is kinetically evolving areas which offer large potential for agencies of all sized to increase efficiency. Cloud Broker acts as a mediator between cloud users and cloud service providers. The main functionality of cloud broker lies in selecting best Cloud Service Providers (CSP) from requirement set defined by cloud user. Request from cloud users are processed by the cloud broker and suited providers are allocated to them. This paper gives detailed review of cloud brokerage services and their method of negotiating with the service providers. Once the SLA is specified by cloud service provider, the cloud broker will negotiate the terms according to the user’s specification. The negotiation can be modeled as a middleware, and its services can be provided as application programming interface.