| Twig_CompilerInterface | Interface implemented by compiler classes. |
| Twig_ExistsLoaderInterface | Adds an exists() method for loaders. |
| Twig_ExtensionInterface | Interface implemented by extension classes. |
| Twig_FilterCallableInterface | Represents a callable template filter. |
| Twig_FilterInterface | Represents a template filter. |
| Twig_FunctionCallableInterface | Represents a callable template function. |
| Twig_FunctionInterface | Represents a template function. |
| Twig_LexerInterface | Interface implemented by lexer classes. |
| Twig_LoaderInterface | Interface all loaders must implement. |
| Twig_NodeInterface | Represents a node in the AST. |
| Twig_NodeOutputInterface | Represents a displayable node in the AST. |
| Twig_NodeVisitorInterface | Twig_NodeVisitorInterface is the interface the all node visitor classes must implement. |
| Twig_ParserInterface | Interface implemented by parser classes. |
| Twig_Sandbox_SecurityPolicyInterface | Interfaces that all security policy classes must implements. |
| Twig_TemplateInterface | Interface implemented by all compiled templates. |
| Twig_TestCallableInterface | Represents a callable template test. |
| Twig_TestInterface | Represents a template test. |
| Twig_TokenParserBrokerInterface | Interface implemented by token parser brokers. |
| Twig_TokenParserInterface | Interface implemented by token parsers. |