curl

curl, at 26 years old, is the most installed open-source tool on Earth, with over 20 billion deployments across cars, TVs, and every operating system. Daniel Stenberg's command-line utility transfers data using over 200 protocols, handling trillions of HTTPS requests annually. Embedded in IoT devices and stock exchanges alike, curl proves that simplicity and ubiquity define true indispensability, supporting use cases from API testing to firmware updates.