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Fiverr Pro
English
$
USD
I will fix production authentication, oauth, jwt, supabase, cors, deployment bugs, apis
Esther B
About this gig
Is your authentication working perfectly in development but breaking after deployment?
I can diagnose and fix production authentication issues involving OAuth, JWT, sessions, cookies, CORS, environment variables, Supabase, PostgreSQL, Next.js and deployment configuration.
I work on the actual cause of the problem instead of applying temporary patches.
Common Issues I Fix
- OAuth login and callback errors
- Google/GitHub authentication issues
- JWT token problems
- Session persistence failures
- Login/signup failures
- 401 and 403 errors
- CORS errors
- Cookie and SameSite issues
- Supabase Auth problems
- PostgreSQL connection/authentication issues
- Missing or incorrect environment variables
- Production redirect URL errors
- Next.js middleware/authentication issues
- Protected route failures
- Vercel/Netlify/AWS deployment authentication bugs
- Authentication working locally but failing in production
I can work with existing applications rather than forcing you to rebuild your authentication system.
Before ordering, send me the error message, technology stack, production URL (if available), and a short explanation of what works locally versus what fails in production.
Get to know Esther B
Esther B
Backend Developer, API Integration, Node js, Supabase, Firebase, AWS, PostgreSQL
- FromGermany
- Member sinceJul 2026
- Avg. response time8 hours
Languages
German, English, Spanish, French, Italian
Backend developer specializing in scalable APIs, database architecture, and secure web applications. I build REST APIs, backend systems, authentication, payment gateways, AI integrations, and automation workflows using Node.js, Express.js, Supabase, Firebase, PostgreSQL, MongoDB, AWS, and SQL. I integrate Stripe, webhooks, third-party APIs, CRMs, and cloud services while optimizing performance, security, and scalability for SaaS, AI, eCommerce, and custom web applications. I also develop serverless functions, API debugging, cloud deployment, database optimization, and custom backend solutions.
Other Software Development Services I Offer
FAQ
My login works locally but fails after deployment. Can you fix it?
Yes. This is one of the main problems this gig targets. I can inspect production environment variables, OAuth URLs, cookies, CORS, sessions, middleware and deployment configuration to identify why authentication behaves differently after deployment.
Can you fix Google OAuth redirect errors?
Yes. I can troubleshoot OAuth client configuration, callback URLs, redirect URI mismatches, environment variables and provider configuration. I can also verify that your development and production OAuth settings are correctly separated.
Can you fix Supabase authentication problems?
Yes. I can troubleshoot Supabase Auth configuration, redirect URLs, session handling, database access, environment variables and frontend/backend integration issues. I can also investigate problems that only appear after deployment.
My JWT authentication returns 401 in production. Can you fix it?
Yes. I can investigate token generation, storage, transmission, verification, expiration, authorization headers, cookies and environment-specific configuration to determine why valid authentication requests are being rejected.
Can you fix authentication problems on Vercel?
Yes. Vercel deployments can expose issues involving environment variables, server/client boundaries, cookies, redirects, middleware and OAuth callbacks. I can troubleshoot the authentication flow specifically in the deployed environment.
Can you fix CORS and cookie authentication issues?
Yes. I can diagnose incorrect origins, credentials configuration, cookie attributes, SameSite settings, secure cookies and frontend/backend domain mismatches that prevent authenticated requests from working correctly.
Can you fix Next.js authentication and middleware bugs?
Yes. I can troubleshoot middleware, protected routes, server-side sessions, client/server authentication state, redirects and authentication logic in Next.js applications.
Do you fix PostgreSQL authentication or Supabase database issues?
Yes. I can investigate database connection problems, credentials, environment variables, Supabase configuration, permissions and issues where authentication succeeds but user data cannot be accessed correctly.
Can you work with my existing authentication system?
Yes. I focus on diagnosing and repairing existing systems. You do not need to rebuild your entire application just because authentication is failing.
What do you need before starting?
Send the relevant error message, your framework/stack, deployment platform, authentication provider, and a brief description of what works in development versus production. For private credentials, provide only the minimum safe information required.
