Lightspeed Companion brings AI-powered email assistance directly into Outlook.
Ask questions about your inbox using natural language. Get answers with citations to specific emails.
Find emails by describing what you're looking for. Semantic search goes beyond keyword matching.
Get quick summaries of long threads and conversations without reading every message.
Emails are indexed locally in your browser. Your data stays on your machine — nothing is stored on our servers.
Download the add-in manifest file to sideload into Outlook. You'll need a Google Gemini API key for AI features (free tier available).
Download Manifest (XML)This is the recommended approach for organizations. It deploys the add-in to all assigned users across every Outlook client automatically.
Open the Admin Center
Go to admin.microsoft.com and sign in with your admin account.
Navigate to Add-ins
Go to Settings → Integrated apps → Add-ins (or directly visit Settings → Add-ins).
Deploy the add-in
Click + Deploy Add-in, then choose I have a URL for the manifest file and enter:
https://thelightspeed.app/companion/manifest.xml
Alternatively, choose I have the manifest file (.xml) on this device and upload the downloaded file. If the file upload fails, use the URL method instead.
Assign users
Choose whether to deploy to Just me, Specific users/groups, or Entire organization. Click Deploy.
Wait for propagation
It can take up to 24 hours for the add-in to appear in all users' Outlook clients. The Lightspeed / AI Chat button will appear in the ribbon when reading emails.
Open Outlook
Go to outlook.office.com and sign in to your Microsoft 365 account.
Open an email
Select any email in your inbox to open the message reading pane.
Open the Add-ins menu
Click the three-dot menu (…) in the toolbar at the top of the message, then select Get Add-ins.
Go to My add-ins
In the Add-ins dialog, click My add-ins in the left sidebar.
Upload the manifest
Scroll down to Custom add-ins and click + Add a custom add-in → Add from file.... Select the lightspeed-companion.xml file you downloaded.
Confirm installation
Click Install on the warning dialog. The "Lightspeed" button will now appear in the toolbar when reading messages.
Open New Outlook
Open the new Outlook for Windows app and select any email message.
Open Add-ins
Click the three-dot menu (…) in the message toolbar, then select Get Add-ins.
Upload the manifest
Navigate to My add-ins → Custom add-ins → + Add a custom add-in → Add from file... and select the downloaded manifest file.
Use the add-in
Open any email and click the Lightspeed / AI Chat button in the ribbon to open the companion panel.
If you're a Microsoft 365 admin, deploy via the Admin Center (see the Admin Center tab above). The add-in will propagate to Classic Outlook within 24 hours.
Sideload the manifest through Outlook on the Web. The add-in syncs to Classic Outlook via your Microsoft 365 account.
Open Outlook on the Web
Go to outlook.office.com and sign in with the same account you use in Classic Outlook.
Upload the manifest in OWA
Open any email, click the three-dot menu (…) → Get Add-ins → My add-ins → Custom add-ins → + Add a custom add-in → Add from file... and upload the manifest.
Restart Classic Outlook
Close and reopen Classic Outlook. The Lightspeed / AI Chat button will appear in the ribbon when reading messages. This may take a few minutes to sync.
Go to File → Manage Add-ins
In Classic Outlook, click File → Manage Add-ins. This opens the OWA add-ins page in your default browser.
Upload the manifest
Follow the OWA sideloading steps above (My add-ins → Custom add-ins → Add from file).
Restart Outlook
Close and reopen Classic Outlook for the add-in to appear.
Open Outlook
Open Outlook for Mac and select any email message.
Open the Add-ins dialog
Click the three-dot menu (…) at the top of the message, then select Get Add-ins.
Upload the manifest
Click My add-ins, then under Custom add-ins, click + Add a custom add-in → Add from file... and select the manifest.
Use the add-in
Click the Lightspeed / AI Chat button in the message toolbar to open the companion panel.
After installing the add-in, click the Lightspeed button while reading any email to open the companion panel. You'll need to:
Try closing and reopening Outlook. If using Outlook on the web, refresh the page. Ensure you uploaded the manifest under Custom add-ins, not the store search.
Your organization's admin may have disabled sideloading. Contact your IT administrator to enable custom add-in sideloading, or ask them to deploy the manifest via centralized deployment.
Ensure you've entered a valid Gemini API key in the Settings panel. The free tier provides generous daily limits for personal use.
To remove the add-in, go to Get Add-ins → My add-ins → Custom add-ins, find Lightspeed Companion, and click the Remove button.