TL;DR
Replit is safe for learning and prototyping, but has unique security considerations for production. Your code runs on shared infrastructure, public Repls expose source code, and secrets management requires attention. The AI features (Ghostwriter/Agent) need the same code review as other AI tools. Use Replit Secrets for sensitive data and consider private Repls for production apps.
What is Replit?
Replit is a browser-based IDE that lets you write, run, and deploy code without local setup. It supports many languages and includes AI coding assistance (Ghostwriter and Replit Agent), collaboration features, and one-click deployment.
Replit is popular for learning, prototyping, and quick deployments, but has different security considerations than traditional development environments.
Our Verdict
What's Good
- Built-in Secrets manager
- HTTPS by default
- Private Repls available
- Good for prototyping
- Easy deployment
What to Watch
- Public Repls expose source
- Shared infrastructure
- AI code needs review
- Limited security config
- Sleep on free tier
Key Security Considerations
1. Public vs Private Repls
By default, Repls can be public, which means:
- Anyone can view your source code
- Your code structure is visible
- Comments and TODOs are exposed
Critical: If your Repl is public, never put API keys, passwords, or sensitive data directly in code files. Even if you delete them later, they may exist in the version history.
2. Secrets Management
Replit has a built-in Secrets feature for storing sensitive data like API keys. When you use Secrets:
- Values are encrypted at rest
- They're injected as environment variables
- They're not visible in public code
- They're not included when forking
Best practice: Always use Replit Secrets for API keys, database credentials, and any sensitive configuration. Access them via environment variables in your code.
3. Shared Infrastructure
Replit runs your code on shared servers. While Replit implements isolation:
- Your Repl shares compute resources with others
- Network isolation may not match dedicated hosting
- Storage is on Replit's infrastructure
For most applications this is fine, but highly sensitive workloads may need dedicated infrastructure.
4. AI-Generated Code (Ghostwriter/Agent)
Replit's AI features have the same security concerns as other AI coding tools:
- Generated code may have vulnerabilities
- Authentication might be incomplete
- Input validation often missing
- Security best practices not automatic
Replit Security Features
| Feature | Free Tier | Paid Plans |
|---|---|---|
| Private Repls | Limited | Unlimited |
| Secrets manager | Yes | Yes |
| HTTPS | Yes | Yes |
| Custom domains | No | Yes |
| Always-on | No (sleeps) | Yes |
| Boosted resources | No | Yes |
When to Use Replit
Good for: Learning to code, prototyping ideas, hackathons, internal tools, personal projects, and applications that don't handle sensitive user data.
Think twice for: Production apps with user authentication, payment processing, healthcare data, or any application where a security breach would have significant consequences.
Security Checklist for Replit
Before Deploying
- Make your Repl private if it contains any business logic
- Move all API keys and credentials to Secrets
- Review AI-generated code for security issues
- Add input validation to all user inputs
- Implement proper authentication if needed
- Test that Secrets aren't exposed in logs or errors
Replit vs Alternatives
| Aspect | Replit | Local Dev + Vercel | Bolt.new |
|---|---|---|---|
| Code privacy | Private Repl required | Fully private | Private by default |
| Infrastructure | Shared | Serverless/dedicated | Shared (StackBlitz) |
| Secrets handling | Built-in Secrets | Env variables | Manual |
| Deployment control | Limited | Full control | Limited |
| Production ready | With care | Yes | After hardening |
Can I run production apps on Replit?
Yes, but with caveats. Use private Repls, store all secrets properly, review AI-generated code, and consider whether shared infrastructure meets your security requirements. Many small projects run fine on Replit, but high-stakes applications may need more control.
Are my Secrets actually secure?
Replit Secrets are encrypted and not visible in your code or when others fork your Repl. However, if your code logs environment variables or exposes them through errors, they could leak. Always test that your secrets aren't accidentally exposed.
What happens when my Repl sleeps?
On the free tier, Repls sleep after inactivity. When a request comes in, there's a cold start delay. For production apps that need reliability, this can cause issues with webhooks, scheduled tasks, or user experience. Paid plans offer always-on hosting.
Is Replit Agent safe to use?
Replit Agent (their AI coding assistant) has the same security considerations as other AI tools. It can generate insecure code, miss authentication, and create vulnerabilities. Always review AI-generated code before deploying, especially authentication and data handling.