The GIAC/SANS approach

GIAC and SANS together offer events, training paths, and a robust community that is often considered a favorite for US and NATO government cyber security professionals, and it is often listed in requirements for the many roles there. Among their offerings is the GIAC Web Application Penetration Tester (GWAPT) certification. GWAPT is a standalone certification that closely mirrors the Cyber Kill Chain, and their curriculum is available only at conferences and through online courses.

The high cost of their training is considered well worth it, but it often limits the breadth of audience that can access their methodology and framework. Consider the GWAPT a more advanced certification, well-worth pursuing as a next-step in your web pen testing career.