# Can You Run Fibr on Your Local Machine?

**Short answer:** No, Fibr cannot run on localhost or private development environments.

Here's why, and what you can do instead.

***

#### Why Fibr Requires a Public URL

The Fibr Script needs to communicate with our servers to:

1. Check which experiments and personalization rules are active
2. Determine which variant to show each visitor
3. Send back analytics and conversion data

This communication requires a publicly accessible URL. When you run a site on `localhost`, `127.0.0.1`, or a private IP address, Fibr's servers can't reach your site to validate the script or deliver experiences.

***

#### What About Private Staging Environments?

The same limitation applies to staging environments that:

* Are behind a VPN
* Require authentication to access
* Use internal network addresses
* Block external traffic

If Fibr can't reach the URL from the public internet, the script won't work.

***

#### How to Test Fibr During Development

**Option 1: Use a public staging environment**

Set up a staging site that's publicly accessible (even if it's not widely known). Add the Fibr Script to this environment and test there before deploying to production.

Tips for staging:

* Use a subdomain like `staging.yoursite.com`
* Add it to your Fibr workspace alongside your production domain
* You can run separate experiments on staging for testing

**Option 2: Use a tunnel service**

Tools like ngrok, Cloudflare Tunnel, or localtunnel create a public URL that points to your local development server.

Example with ngrok:

bash

```bash
ngrok http 3000
```

This gives you a URL like `https://abc123.ngrok.io` that Fibr can access. Add this URL to your Fibr workspace for testing.

Note: Tunnel URLs are temporary. You'll need to update your Fibr settings each time the URL changes.

**Option 3: Test in production with limited traffic**

If staging isn't an option, you can test safely in production:

1. Create an experiment with a small traffic allocation (e.g., 5%)
2. Use audience targeting to limit it to internal team members (by UTM parameter, cookie, or IP range)
3. Validate the experience works correctly
4. Gradually increase traffic once confirmed

***

#### Validating Your Script Locally

While Fibr won't fully function on localhost, you can still check if the script is installed correctly:

1. Open your local site in a browser
2. Open Developer Tools → Console
3. Look for any Fibr-related errors

If the script loads without errors, it's installed correctly and will work once deployed to a public URL.

***

#### Need Help Testing?

If you're having trouble setting up a testing workflow, reach out to <support@fibr.ai>. We can help you find a solution that works for your development process.