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Install and configure Vercel Speed Insights#1

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Install and configure Vercel Speed Insights#1
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vercel/install-and-configure-vercel-s-w4oi31

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@vercel vercel Bot commented Jun 14, 2026

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Vercel Speed Insights Implementation Report

Summary

Successfully implemented Vercel Speed Insights for this FastAPI project using the vanilla JavaScript approach.

What Was Done

1. Documentation Research

  • Fetched the latest official Vercel Speed Insights documentation from https://vercel.com/docs/speed-insights/quickstart
  • Determined that since this is a Python/FastAPI backend project (not a JavaScript framework), the vanilla JavaScript script injection method is the appropriate implementation approach
  • No npm package installation required for this Python-based project

2. Implementation Details

Modified Files:

  • main.py - Added Speed Insights tracking scripts to the HTML response

Changes Made:

  • Injected the Speed Insights initialization script into the <head> section of the HTML response
  • Added the deferred Speed Insights tracking script that loads from /_vercel/speed-insights/script.js

Code Added:

<script>
    window.si = window.si || function () { (window.siq = window.siq || []).push(arguments); };
</script>
<script defer src="/_vercel/speed-insights/script.js"></script>

3. Technical Approach

Since this is a FastAPI application that serves HTML directly from Python code (not a Node.js/JavaScript framework), the implementation follows Vercel's vanilla JavaScript approach:

  1. No Package Installation: Unlike React, Next.js, or other JS frameworks, this project doesn't require installing the @vercel/speed-insights npm package
  2. Script Injection: The Speed Insights tracking is enabled by injecting JavaScript directly into the HTML <head> section
  3. Automatic Detection: When deployed on Vercel, the platform automatically serves the Speed Insights script from /_vercel/speed-insights/script.js

4. How It Works

  1. The window.si function initializes a queue for Speed Insights events
  2. The deferred script loads asynchronously without blocking page rendering
  3. Once deployed to Vercel, the platform will:
    • Enable the Speed Insights script endpoint automatically
    • Start collecting Web Vitals and performance metrics
    • Display the data in the Vercel dashboard under Speed Insights

5. Testing

  • Verified Python syntax is valid (no compilation errors)
  • Confirmed the script injection is properly placed in the HTML head section
  • The implementation follows Vercel's official documentation for vanilla JavaScript projects

Next Steps

To complete the Speed Insights setup:

  1. Deploy to Vercel: Push these changes and deploy to Vercel
  2. Enable in Dashboard: Navigate to your project in the Vercel dashboard and enable Speed Insights if not already enabled
  3. Verify: After deployment, check the page source to confirm the Speed Insights script is loading
  4. Monitor: View performance metrics in the Vercel dashboard under the Speed Insights section

Notes

  • The Speed Insights script loads asynchronously with the defer attribute to avoid blocking page load
  • The script will only track metrics in production deployments on Vercel
  • No additional configuration is needed for basic functionality
  • The implementation preserves all existing HTML structure and styling

View Project · Speed Insights

Created by madib036 with Vercel Agent

# Vercel Speed Insights Implementation Report

## Summary
Successfully implemented Vercel Speed Insights for this FastAPI project using the vanilla JavaScript approach.

## What Was Done

### 1. Documentation Research
- Fetched the latest official Vercel Speed Insights documentation from https://vercel.com/docs/speed-insights/quickstart
- Determined that since this is a Python/FastAPI backend project (not a JavaScript framework), the vanilla JavaScript script injection method is the appropriate implementation approach
- No npm package installation required for this Python-based project

### 2. Implementation Details

**Modified Files:**
- `main.py` - Added Speed Insights tracking scripts to the HTML response

**Changes Made:**
- Injected the Speed Insights initialization script into the `<head>` section of the HTML response
- Added the deferred Speed Insights tracking script that loads from `/_vercel/speed-insights/script.js`

**Code Added:**
```html
<script>
    window.si = window.si || function () { (window.siq = window.siq || []).push(arguments); };
</script>
<script defer src="/_vercel/speed-insights/script.js"></script>
```

### 3. Technical Approach

Since this is a FastAPI application that serves HTML directly from Python code (not a Node.js/JavaScript framework), the implementation follows Vercel's vanilla JavaScript approach:

1. **No Package Installation**: Unlike React, Next.js, or other JS frameworks, this project doesn't require installing the `@vercel/speed-insights` npm package
2. **Script Injection**: The Speed Insights tracking is enabled by injecting JavaScript directly into the HTML `<head>` section
3. **Automatic Detection**: When deployed on Vercel, the platform automatically serves the Speed Insights script from `/_vercel/speed-insights/script.js`

### 4. How It Works

1. The `window.si` function initializes a queue for Speed Insights events
2. The deferred script loads asynchronously without blocking page rendering
3. Once deployed to Vercel, the platform will:
   - Enable the Speed Insights script endpoint automatically
   - Start collecting Web Vitals and performance metrics
   - Display the data in the Vercel dashboard under Speed Insights

### 5. Testing

- Verified Python syntax is valid (no compilation errors)
- Confirmed the script injection is properly placed in the HTML head section
- The implementation follows Vercel's official documentation for vanilla JavaScript projects

## Next Steps

To complete the Speed Insights setup:

1. **Deploy to Vercel**: Push these changes and deploy to Vercel
2. **Enable in Dashboard**: Navigate to your project in the Vercel dashboard and enable Speed Insights if not already enabled
3. **Verify**: After deployment, check the page source to confirm the Speed Insights script is loading
4. **Monitor**: View performance metrics in the Vercel dashboard under the Speed Insights section

## Notes

- The Speed Insights script loads asynchronously with the `defer` attribute to avoid blocking page load
- The script will only track metrics in production deployments on Vercel
- No additional configuration is needed for basic functionality
- The implementation preserves all existing HTML structure and styling

Co-authored-by: Vercel <vercel[bot]@users.noreply.github.com>
@vercel

vercel Bot commented Jun 14, 2026

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Project Deployment Actions Updated (UTC)
api Ready Ready Preview, Comment Jun 14, 2026 5:03am

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