The Call Level Interface (CLI) is an application programming interface (API) and software standard to embed Structured Query Language (SQL) code in a host program as defined in a joint standard by the International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC): ISO/IEC 9075-3:2003. The Call Level Interface defines how a program should send SQL queries to the database management system (DBMS) and how the returned recordsets should be handled by the application in a consistent way. Developed in the early 1990s, the API was defined only for the programming languages C and COBOL.

The interface is part of what The Open Group, publishes in a part of the X/Open Portability Guide, termed the Common Application Environment, which is intended to be a wide standard for programming open applications, i.e., applications from different programming teams and different vendors that can interoperate efficiently. SQL/CLI provides an international standard implementation-independent CLI to access SQL databases. Client–server tools can easily access databases through dynamic-link libraries (DLL). It supports and encourages a rich set of client–server tools.

The most widespread use of the CLI standard is the basis of the Open Database Connectivity (ODBC) specification, which is widely used to allow applications to transparently access database systems from different vendors. The current version of the API, ODBC 3.52, incorporates features from both the ISO and X/Open standards. Examples of languages that support Call Level Interface are ANSI C, C#, Visual Basic .NET (VB.NET), Java, Pascal, and Fortran.