What’s your biggest concern when designing an API for public use vs. one for your internal team? Simplicity? Security? Something else?

Security is the prime concern for building APIs for public use, then comes Simplicity that eases the adoption curve and then scalability for sustaining the increased adoption. Internal APIs can be designed for tighter coupling with internal Apps and may not follow the general principles of API design.

Security is essential but hopefully you have a centralized solution for all your public facing apis, either st the gateway level or a shared common library/practice. After security ease of use and making sure is not just a CRUD api but take in consideration business rules and can combine and expose complex domain models without necessarily leaking your internal data structure.

It's essential security in a public API is included from the start, and is not an afterthought.

Further, you will want to ensure a sensible naming scheme that includes versioning so your public users don't find their code stops working when you make updates.

Designing APIs for public use and internal teams differ in key concerns. For public APIs, security and scaling are top priorities due to potential external threats, the need to protect user data, and handling varying usage demands from a diverse user base. Additionally, calculating traffic load, accounting for regionality, and ensuring seamless deploys become more challenging with public APIs, making careful planning and infrastructure management essential.