You don't have to evaluate authorization/token request parameters. Forward them right away to Authlete so that it can do protocol handling and token management on your OAuth/OIDC server's behalf, and tell you what to do next.
Authlete's APIs are carefully crafted to focus on the core of OAuth/OIDC. You can build your OAuth/OIDC servers with Authlete, or integrate Authlete with your service components, especially identity and access management (IAM) and API gateways.
Authlete is an OpenID Certified and Financial-grade API (FAPI) compliant solution, and supports many other OAuth/OIDC extensions that include Identity Assurance and Grant Management.