In most Microsoft-centric organisations the operational detail lives in Excel workbooks on SharePoint or OneDrive — budgets, headcount plans, project trackers, stock counts. They are collaborative, familiar, and effectively invisible to every other system in the company.
Dataloom connects to those workbooks through the Microsoft Graph API and turns their worksheets into REST endpoints. Each worksheet behaves as a table, the header row provides the field names, and the rows become records that any application can request over HTTP.
The workbook does not move and does not change how it is used. Your team keeps editing it in Excel exactly as before, while everything else gains a proper, documented, key-protected way to read it.
Connecting an Excel Online workbook
Access goes through a Microsoft Entra ID application rather than a personal sign-in. Register an app, grant it the Files.ReadWrite.All application permission, have an administrator consent to it, and create a client secret. Dataloom then needs the tenant ID, client ID and client secret, together with the URL of the workbook you want to connect.
That admin-consent step is the part worth planning for: application permissions are tenant-wide and need approval from someone with the rights to grant it. It is a one-off, and it is what allows the connection to keep working without depending on any individual person remaining at the company.
Organisational OneDrive for Business and SharePoint document libraries are supported. Once connected, Dataloom reads the worksheets in the workbook and their header rows, and you choose which ones to publish and which columns each endpoint returns.
What you get with Excel Online
- Worksheets become tables, header rows become field names
- Connects through the Microsoft Graph API
- Supports SharePoint document libraries and OneDrive for Business
- Service-principal authentication with tenant-wide admin consent
- Filtering, sorting and pagination over worksheet rows
- The workbook stays fully editable in Excel
An example endpoint
Departments over budget for the current quarter.
GET /finance-workbook/budget2026
?filter={"Quarter":"Q3","Variance":{"lt":0}}
&sort=Variance&order=asc
&page=1&pageSize=10
X-API-Key: your_api_key{
"data": [
{ "Department": "Field Operations", "Quarter": "Q3",
"Budget": 420000, "Actual": 486300, "Variance": -66300 },
{ "Department": "Marketing", "Quarter": "Q3",
"Budget": 180000, "Actual": 201450, "Variance": -21450 }
],
"meta": { "page": 1, "pageSize": 10, "totalCount": 4,
"totalPages": 1, "hasNextPage": false }
}Filtering, sorting and pagination work the same way on every endpoint, whatever the source. See the no-code API builder for how endpoints are put together.
Connect Claude to Excel Online
Every published worksheet endpoint is also a tool on your workspace’s hosted MCP server, so an AI assistant can read live workbook data without anyone attaching a file to a message. The values it sees are the values in the workbook at that moment.
That turns a monthly reporting chore into a question. "Which departments are over budget this quarter, worst first?" becomes a single filtered call against the endpoint you published, answered from the workbook your finance team is already maintaining.
Exposure stays deliberate. Only the worksheets you published are reachable, the assistant authenticates through OAuth 2.1, and access for any individual assistant can be revoked from your workspace without touching the underlying Microsoft app registration.
// mcp-config.json
{
"mcpServers": {
"dataloom": {
"url": "https://mcp.dataloom.cloud/w/your-workspace",
"transport": "http"
}
}
}Read more about the hosted MCP server, or follow the step-by-step setup guide.
Excel Online questions, answered
Why does this need admin consent?
Dataloom uses a Microsoft Entra ID application with the Files.ReadWrite.All application permission. Application permissions are tenant-wide, so an administrator has to consent once before the connection can be used.
Does it work with personal OneDrive accounts?
It supports organisational OneDrive for Business and SharePoint. Personal consumer OneDrive accounts are not supported.
How are worksheet columns determined?
From the first row of each worksheet, the same way a table header works. Those values become your API field names.
Can people keep editing the workbook normally?
Yes. The workbook remains a normal Excel file in SharePoint or OneDrive, and Dataloom reads it live, so edits show up through the API.