Replit
api
CORS Credentials and Cookies Not Sent
Authenticated API requests fail because cookies aren't sent. CORS blocks credentials even after preflight succeeds.
Credentials mode and CORS headers must align for cookies to transmit.
Error Messages You Might See
Credentials mode is 'include' but Access-Control-Allow-Credentials header is missing
Access-Control-Allow-Origin cannot use wildcard
Common Causes
- Client not sending credentials: 'include' in fetch
- Server not sending Access-Control-Allow-Credentials: true
- Access-Control-Allow-Origin set to * (incompatible with credentials)
- Cookie SameSite=Strict blocking cross-site cookies
How to Fix It
Client: fetch(url, { credentials: 'include' }). Server: response header Access-Control-Allow-Credentials: true. Set Access-Control-Allow-Origin to specific domain, NOT *. Ensure cookies have SameSite=None; Secure for cross-site. Configure Spring CORS with allowedOriginPatterns and allowCredentials=true.
Real developers can help you.
Matthew Jordan
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I got a lot of experience in building Long-horizon AI Agents in production, Backend apps that scale to millions of users and frontend knowledge as well.
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As an INFJ-T, I approach development with a "systems-thinking" mindset—balancing technical precision with a deep understanding of user needs. I particularly enjoy the challenge of architecting Vertical AI SaaS and optimizing Small Language Models (SLMs) to solve specific, real-world business problems. Whether I'm in a CTO-level leadership role or hands-on with the code, I thrive on building tools that turn complex data into actionable value.
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hanson1014
Full-stack developer experienced in fixing and deploying AI-generated apps from Lovable, Bolt.new, Cursor, and Replit. I specialize in debugging Supabase integration issues (auth flows, RLS policies, database connections), fixing broken deployments, resolving routing/blank screen problems, and cleaning up messy React/Vite codebases. I also build production apps with the Claude API and have shipped a Mac desktop dev tool (Nexterm from scratch. Based in Hong Kong, fast turnaround.
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Get HelpFrequently Asked Questions
How do I send cookies with fetch?
fetch(url, { credentials: 'include' }) - must also set server headers correctly
Can I use Access-Control-Allow-Origin: *?
Not with credentials. Use specific domain or null for local testing