For a solo developer looking to deploy latency-sensitive applications, choose Fly.io. Its ability to deploy applications close to users while keeping idle costs low with scale-to-zero machines makes it ideal for maximizing performance and minimizing costs. However, be prepared for potentially unpredictable billing and the need for more operational knowledge than a fully managed service offers.
On the other hand, if you're an API developer or an open-source enthusiast who values a free solution, opt for Hoppscotch. It provides a robust API development ecosystem without any costs, is suitable for offline use, and works across various platforms. However, if you require advanced features or extensive third-party integrations, you might want to look elsewhere, as it may not meet your needs.