Startups without customers face challenges in deciding which integrations to build, but can employ strategies such as analyzing competitors' offerings and conducting market research on buyer personas to identify essential integrations. They should also assess API availability and the quality of documentation to prioritize integration opportunities effectively. Once these strategies have been implemented, startups may find themselves needing to build numerous integrations quickly and can utilize platforms like Merge, which provides a unified API solution to offer hundreds of integrations across various software categories. Merge not only facilitates these integrations but also offers robust management tools and ongoing support, allowing startups to focus on their core products while ensuring reliable and performant integrations.