SAST and DAST
Static and dynamic analysis tuned to your codebase rather than run at default settings. The value is not in running the tool, which you can do yourself. It is in cutting the false positive rate to something your developers will actually triage, and integrating results into the pipeline so findings surface at the pull request rather than in a quarterly report.
Secure code review
Manual review by people who read code for a living, focused where automated analysis is weakest: authorization logic, cryptographic implementation, state handling, and business rules a scanner cannot reason about. Typically scoped to the highest-risk paths rather than the entire repository.
Threat modeling
Structured analysis of what could go wrong with a system before it is built, and what an attacker would target once it is. Produces a documented set of threats, existing mitigations, and gaps, which doubles as evidence for several compliance frameworks.
API testing
Design and specification review of your APIs: authorization at the object level, rate limiting, data exposure in responses, and the difference between what the documentation promises and what the implementation permits. Runtime adversarial API testing is part of penetration testing.
See also: Penetration Testing
Open source analysis
Dependency and supply chain review: known vulnerabilities in what you have pulled in, transitive dependencies nobody chose deliberately, license obligations, and the maintenance health of packages your product depends on. Increasingly a customer and regulatory requirement rather than an internal nicety.