curl is the universal data transfer tool of the internet. Supporting over 25 protocols including HTTP, HTTPS, FTP, and WebSocket, it is pre-installed on virtually every Unix-like system and has become the de facto standard for making network requests from the command line.
AI agents use curl as their primary means of interacting with web APIs — fetching data, posting payloads, downloading files, and testing endpoints. Its comprehensive flag system allows fine-grained control over headers, authentication, timeouts, retries, and output formatting.
With over two decades of continuous development, curl handles edge cases that simpler HTTP clients miss: connection reuse, redirect chains, certificate pinning, proxy tunneling, and rate limiting. Its silent mode (-s) and JSON output options make it particularly well-suited for scripted workflows where clean, parseable output is essential.