(Senior) Fullstack Engineer - Freelance

Fluency in Polish and English OAuth 2.0 Instagram Graph API Meta App Review experience Passport.js / NextAuth.js / OmniAuth (depending on stack) (Nice to have) JWT (JSON Web Tokens) (Nice to have) OpenID Connect (OIDC) (Nice to have) Facebook Login Kit (Nice to have) GDPR compliance basics (Nice to have)

Owning the 'App Review' Process: Managing the complete verification cycle with Meta (including creating required screencasts and writing scope justifications) to ensure the app is approved for Live access. Meta Ecosystem Configuration: Correctly setting up the application environment in the Meta for Developers console. OAuth Strategy & Implementation: Implementing the 'Login with Instagram' flow to securely fetch specific influencer data points needed for profiling. Technical Advisory: Acting as the subject-matter expert to guide the client through Meta's strict policies and prevent application rejection.