curl
2vendors are named alongside curl. 3 sources reference it, most recently Netskope Explains Blockchain Dead Drop Resolvers for C2 Fetches (Aug 2026).
What is curl?
curl is a command-line tool and client-side URL transfer library for retrieving and sending data over a wide range of network protocols (network transport / application networking).
- Data transfer over multiple protocols including Hypertext Transfer Protocol (HTTP), HTTPS, File Transfer Protocol (FTP), FTPS, Secure Copy (SCP), SSH File Transfer Protocol (SFTP), LDAP, Simple Mail Transfer Protocol (SMTP), POP3, IMAP and others (network transport)
- libcurl library for embedding URL transfer capabilities into applications (developer library / SDK)
- Support for TLS-based secure transport with integrations to multiple Transport Layer Security (TLS) backends (security / encryption)
- Authentication, cookies, proxies, redirects, and upload/download options for HTTP and related protocols (web client / HTTP tooling)
- Cross-platform availability on many operating systems and Central Processing Unit (CPU) architectures, with bindings in multiple languages (cross-platform tooling)
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More About curl
curl is a client-side URL transfer tool and library (network transport / application networking) designed for sending and receiving data using a variety of common Internet protocols. It addresses the need for programmable, scriptable, and automatable data transfers from the command line and within applications, without requiring interactive user input. The project provides both the curl command-line tool and the libcurl library, giving users and developers a consistent interface for network data transfer operations across platforms.
The curl command-line tool (CLI utility) supports operations over multiple protocols, including HTTP, HTTPS, FTP, FTPS, SCP, SFTP, LDAP, SMTP, POP3, IMAP and others, as documented on the project site. It can perform GET, POST, PUT and other HTTP methods (web client / HTTP tooling), handle file uploads and downloads, follow redirects, manage cookies, and work with proxies. The tool exposes extensive options for headers, request bodies, authentication methods, and protocol-specific behavior, enabling integration into shell scripts, Continuous Integration (CI) pipelines, and automated jobs in server and desktop environments.
libcurl is the reusable transfer library (developer library / SDK) that powers the curl tool and is intended for integration into third-party software. It offers a C Application Programming Interface (API) with bindings available for many programming languages, enabling applications to perform URL-based transfers using the same protocol support and features as the Command-Line Interface (CLI). libcurl supports synchronous and asynchronous usage models, connection reuse, and configuration of timeouts, headers, authentication, and security settings. This library is widely embedded in other tools and applications that require HTTP or other protocol client capabilities.
Security and encryption are core aspects of curl’s protocol support (security / encryption). curl integrates with several TLS backends, such as OpenSSL, wolfSSL, and others listed on the official site, to provide HTTPS and TLS-secured protocol variants. It supports certificate verification, client certificates, and configuration of cipher suites and TLS options, which are important for enterprise compliance and secure communication requirements.
In enterprise and institutional environments, curl is used for automation of web service interactions, batch data transfers, system monitoring, and integration testing of HTTP APIs (IT operations / DevOps tooling). Administrators and engineers use it to script interactions with REST-like services, upload or fetch files from servers, and validate endpoints. Its cross-platform nature allows consistent behavior on Linux, Windows, macOS, and many other operating systems, which supports heterogeneous infrastructure deployments.
From a directory and taxonomy perspective, curl belongs primarily in the categories of network client tooling, HTTP and URL transfer utilities, and embeddable networking libraries. It intersects with infrastructure automation, application development, and security-focused workloads due to its role in authenticated, encrypted, and scripted data transfer over widely deployed Internet protocols.