What factors determine the size and reach of a custom audience on Facebook?

There are many tools and software options available that can help you analyze and segment your customer data effectively. Here are some popular options:

1. **Customer Relationship Management (CRM) systems**: CRM systems like Salesforce, HubSpot, and Zoho CRM can help you manage your customer data and create segments based on various criteria, such as demographics, behavior, and purchase history.
2. **Data Analytics platforms**: Data analytics platforms like Google Analytics, Adobe Analytics, and Tableau can help you analyze your customer data and create segments based on various metrics, such as website traffic, conversion rates, and customer lifetime value.
3. **Customer Data Platforms (CDPs)**: CDPs like Segment, Tealium, and Treasure Data can help you collect, unify, and analyze customer data from multiple sources, and create segments based on various criteria, such as behavior, demographics, and purchase history.
4. **Predictive Analytics tools**: Predictive analytics tools like RapidMiner, Alteryx, and DataRobot can help you analyze customer data and create predictive models that identify patterns and trends, and create segments based on these insights.
5. **Marketing Automation platforms**: Marketing automation platforms like Marketo, Pardot, and Mailchimp can help you automate marketing campaigns and create segments based on various criteria, such as engagement, behavior, and demographics.
6. **Data Visualization tools**: Data visualization tools like Power BI, Looker, and Chartio can help you create visual representations of your customer data, making it easier to identify trends and patterns, and create segments based on these insights.

When choosing a tool or software option, consider factors such as ease of use, scalability, integration with other systems, and cost. It's also important to ensure that the tool or software complies with relevant data privacy regulations, such as GDPR and CCPA.

Ultimately, the best tool or software for your business will depend on your specific needs and goals, as well as the size and complexity of your customer data. It may be helpful to consult with a data analytics or marketing technology expert to determine the best solution for your business.