I will fix nextjs supabase auth API and webhook errors

Is your Next.js app stuck in a login loop, returning 401/403 errors, or failing to receive webhooks?

I fix specific, reproducible problems in existing Next.js and React applications. My focus is Supabase authentication, API endpoints, webhook handlers, and frontend/backend integration errors.

What I can help with:

- Supabase signup, login, sessions, redirects and callback errors

- API fetch failures and 401/403/500 responses

- Webhook request handling, validation and event processing

- Deployment configuration causing broken authentication or API calls

How I work:

1. Review reproduction steps and sanitized error logs.

2. Trace the root cause and confirm the scope.

3. Apply a scoped fix in the existing codebase.

4. Run relevant checks and explain what changed.

Basic: one reproducible issue.

Standard: one related authentication or API flow with verification notes.

Premium: up to three agreed issues with checks, documentation and code comments.

Please message before ordering with the error, expected behavior and tech stack. Do not share passwords or API secrets in chat. Full app rewrites, new features and third-party outages are not included.