Common Issues general

My App Works on My Computer but Not When I Share the Link

Everything looks perfect when you test your app on your own computer. But when you send the link to a friend, customer, or investor, they see errors, a blank page, or something completely broken. It's embarrassing and confusing.

This happens because your computer has a special setup that makes the app work — things like saved passwords, local files, or settings that only exist on your machine. When someone else opens the link, none of that is available, so the app falls apart.

It might also be that your app is still running only on your computer (localhost) and isn't actually published to the internet yet, even though you have a link that looks like it should work.

Error Messages You Might See

This site can't be reached 404 Not Found Application error - check logs Blank white page Failed to load resource
This site can't be reached404 Not FoundApplication error - check logsBlank white pageFailed to load resource

Common Causes

  • App isn't actually deployed — You're running it on your computer (localhost) and sharing a link that only works on your machine
  • Missing environment variables — Secret keys and passwords are saved on your computer but weren't added to the hosting platform
  • Database not connected in production — Your app talks to a local database on your computer, not one on the internet
  • Mixed HTTP and HTTPS — Your live site uses HTTPS but some resources are loaded over HTTP, which browsers block
  • Browser cache showing old version — You see the working version from your cache, but others get the broken deployed version

How to Fix It

  1. Test in a private/incognito window — Open your link in an incognito browser tab to see what others actually see
  2. Check your hosting platform — Make sure your app is actually deployed and the hosting shows it as "live" or "active"
  3. Add your secret keys to the hosting — Any passwords or API keys on your computer need to be added to your hosting platform's environment variables section
  4. Check the deployment logs — Look at your hosting platform for error messages during the build or deploy process
  5. Test on your phone — Open the link on your phone (not connected to your home WiFi) to confirm it works outside your network

Real developers can help you.

AUXLE AUXLE I am a Full Stack Developer experienced in building Websites, Web apps and Cross Platform Mobile Apps for Startups and Companies. Richard McSorley Richard McSorley Full-Stack Software Engineer with 8+ years building high-performance applications for enterprise clients. Shipped production systems at Walmart (4,000+ stores), Cigna (20M+ users), and Arkansas Blue Cross. 5 patents in retail/supply chain tech. Currently focused on AI integrations, automation tools, and TypeScript-first architectures. Costea Adrian Costea Adrian Embedded Engineer specilizing in perception systems. Latest project was a adas camera calibration system. Simon A. Simon A. I'm a backend developer building APIs, emulators, and interactive game systems. Professionally, I've developed Java/Spring reporting solutions, managed relational and NoSQL databases, and implemented CI/CD workflows. Daniel Vázquez Daniel Vázquez Software Engineer with over 10 years of experience on Startups, Government, big tech industry & consulting. Vlad Temian Vlad Temian 15+ years shipping production infrastructure for startups. Former CTO at qed.builders (acquired by The Sandbox). Cursor ambassador and agentic tooling builder. I've scaled systems, automated deployments, and built observability tools for AI coding workflows. I specialize in taking vibe-coded apps from broken prototype to production-ready: fixing Supabase auth/RLS, Stripe integrations, deployment pipelines, and cleaning up AI-generated spaghetti. I build tools in this space (agentprobe, claudebin, micode) and understand both sides: how AI generates code and why it breaks. https://blog.vtemian.com/ legrab legrab I'll fill this later Prakash Prajapati Prakash Prajapati I’m a Senior Python Developer specializing in building secure, scalable, and highly available systems. I work primarily with Python, Django, FastAPI, Docker, PostgreSQL, and modern AI tooling such as PydanticAI, focusing on clean architecture, strong design principles, and reliable DevOps practices. I enjoy solving complex engineering problems and designing systems that are maintainable, resilient, and built to scale. zipking zipking I am a technologist and product builder dedicated to creating high-impact solutions at the intersection of AI and specialized markets. Currently, I am focused on PropScan (EstateGuard), an AI-driven SaaS platform tailored for the Japanese real estate industry, and exploring the potential of Archify. 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. PawelPloszaj PawelPloszaj I'm fronted developer with 10+ years of experience with big projects. I have small backend background too

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Frequently Asked Questions

What does 'localhost' mean?

Localhost means the app is running only on your own computer. It's like a private preview. To let others see it, you need to deploy (publish) it to a hosting service like Vercel, Netlify, or Heroku.

Why does it work in my browser but not my friend's?

Your browser might be showing a cached (saved) version, or your computer has settings and passwords that the live version doesn't have. Always test in an incognito window to see the real version.

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