Salesforce is world's most popular CRM. So why look for an alternative? First, it's incredibly expensive. It starts at $25 per user per month, when billed annually, and quickly escalates up to $300 per user per month. Salesforce also tries to lock you into a a long-term contract. Second, there is no self-hosted option for Salesforce. There's simply no way to 'own' Salesforce - you are stuck paying forever. Third, if you want to customize Salesforce, even when it's a minor modification, get ready to pay Salesforce consultants $200+/hr for their work. If you are looking for a free Salesforce alternative, Bitrix24 is an ideal replacement. Here's a detailed feature comparison between the two.
* Please note that the information may have changed since the publication. For current prices and features please visit Bitrix24 pricing page.