Algebraic quantum field theory is a mathematical framework to investigate quantum field theories on Lorentzian spacetimes from a model-independent perspective. We describe algebraic quantum field theories as algebras over a certain colored operad. This operadic formulation allows to treat the commutativity of observables on causally disjoint spacetime regions (the so-called Einstein causality) intrinsically and enables us to set up a local-to-global extension for algebraic quantum field theories based on Fredenhagen's universal algebra construction. As a natural consequence of the operadic approach, we obtain a homotopy theory for differential graded algebraic quantum field theories. While this is mathematically interesting since it naturally leads to a homotopical relaxation of Einstein causality, we argue that it is also necessary to address open problems in quantum gauge theory. As a first non-trivial example of a non-strict homotopical algebraic quantum field theory, we discuss the homotopy orbifold of an algebraic quantum field theory on a category fibered in groupoids. The resulting theory can be interpreted as a fiber-wise groupoid cohomology with coefficients in a strict algebraic quantum field theory.