An online crypto exchange is a platform where users can buy, sell, and trade cryptocurrencies. To build an online crypto exchange, a programming language that is secure, scalable, and has a large developer community is ideal. Some commonly used languages for building online crypto exchanges are:

1. Node.js - A server-side JavaScript language, popular for its fast performance and large developer community.

2. Ruby on Rails - A web application framework built in the Ruby language, known for its ease of use and strong security features.

3. Go (Golang) - A statically typed, compiled language created by Google, known for its performance and scalability.

4. Python - A general-purpose language with a strong ecosystem and large developer community, suitable for building complex applications.

Ultimately, the choice of language depends on the specific requirements and goals of the project.

Online CRM (Customer Relationship Management) is a web-based software application that helps businesses manage customer interactions and data throughout the customer lifecycle, with the goal of improving customer relationships and driving sales growth. Key features of online CRMs include:

1. Contact Management: Storing and organizing customer data such as contact information, communication history, and purchase history.

2. Sales Management: Tracking sales opportunities and automating sales processes, such as lead generation and follow-up.

3. Marketing Automation: Automating and personalizing marketing campaigns, such as email and social media outreach.

4. Analytics & Reporting: Providing insights into customer behavior and sales performance, through dashboards and reporting tools.

5. Collaboration: Allowing teams to work together and share customer information, such as notes and tasks.

Online CRMs can be accessed from any device with an internet connection and offer real-time data updates, making them a useful tool for remote and distributed teams.