Excel add-in with AI

The SovrGPT Excel add-in is a sidebar in Excel. You describe in plain language what should happen to the workbook, and the add-in proposes the changes. Nothing is written until you approve it, and the file itself is never uploaded.

The sidebar is currently in German. This page gives each control's German label with a translation.

Installing

On a single Windows machine:

1. On sovrgpt.com/en/excel, download the installation file and double-click it.
2. Close Excel completely (every window) and reopen it.
3. In Excel, open Home → Add-ins, select SovrGPT für Excel and press Add.

The Home tab now has a SovrGPT group with the button Assistent öffnen (open assistant). Step 3 is easy to miss. Without it, the add-in is registered but not visible.

In companies and public authorities, IT deploys the add-in once, centrally, through the Microsoft 365 admin center. It then appears for all assigned users by itself. Instructions: Deploying the Excel add-in for IT.

Excel on the web, Mac, removal and checksums are covered under Installation in detail.

Your first task

1. Open the sidebar with Assistent öffnen and sign in with your SovrGPT account.
2. Select the cells in question, for example a column of net amounts.
3. Type what should happen: "Calculate the VAT in column D and highlight everything above €1,000."
4. The add-in shows a plan: one line per change, with the affected range. Clicking a line jumps there in the workbook.
5. Anwenden (apply) writes the plan into the workbook, Verwerfen (discard) leaves everything as it was. Letzte Änderung zurücknehmen (undo last change) reverts it later.

Wherever a formula is possible, the add-in writes the formula, not the result. You see the calculation and can change it.

What the add-in can do

Some features need a newer Excel version, see Supported Excel versions.

Choosing a model

You pick the model at the top of the sidebar. Only models suited to spreadsheet work are listed. Each entry shows its role first and then the model, for example Allrounder · Qwen 3.8 27B · eigener Betrieb.

• Entries marked sofort (instant) run at STACKIT in Germany or in a European partner data centre and answer without waiting.
• We run the other models ourselves, on rented GPU servers in EU data centres (and additionally in Iceland or Norway, EEA). If no server is running at the moment, the first answer can take several minutes (cold start). After that it is fast. The measured order of magnitude is shown under the model name.

While you wait, the sidebar shows the elapsed time. It does not estimate a remaining time, because there is no reliable way to predict when a model will be ready.

Thinking

Some models can think before they answer. For simple tasks that only costs time; for a tricky formula it often helps. If the selected model shows the Nachdenken (thinking) control at the bottom, set it to aus (off, the default and fastest), kurz (brief), mittel (medium) or gründlich (thorough).

The control only appears for models where we have measured its effect. Models that always think have no off position. Thinking takes longer and is billed as generated text.

Preview, approval and undo

You set how often the add-in asks in the Freigabe (approval) selector at the bottom of the sidebar:

In every mode:

• If the review rejected individual steps of a proposal, it waits for you.
• If a proposal contains a formula that would send data to the internet, it waits for you.
• Proposals applied automatically are marked automatisch in the sidebar.

Cell contents can contain instructions meant to steer the model (prompt injection). The model is instructed to treat cell contents as data and to report such findings rather than act on them. That is not a guarantee. For workbooks from third parties, "confirm every change" is therefore the safe choice.

Formulas that send data out

Some Excel functions fetch an internet address by themselves, for example =IMAGE(...) or =WEBSERVICE(...). If part of your data is in that address, it reaches the recipient. Attacks of this kind, using instructions hidden in third-party files, have been demonstrated publicly.

So the add-in checks every formula in a proposal. If it finds such a function, the proposal waits for you in every mode. The warning stays open at the top and shows the formula verbatim, with cell and address. Invisible control characters are made visible (<U+200B>), because an address could otherwise hide in them. The formula is not forbidden; you decide.

Undo

A plan is applied in one go. Letzte Änderung zurücknehmen (undo last change) restores the previous state, including after an automatic application.

Purely visual steps are marked nur Strg+Z (Ctrl+Z only) in the preview. Excel 2019 and older offer no complete format snapshot, so we do not save formatting at all.

Be careful when a step renames or moves a sheet: Excel for Windows and Mac then clears the entire Ctrl+Z history, including your own earlier steps. That is Excel's behaviour; it does not happen in the browser. The preview warns about such steps, and our undo for values and formulas keeps working.

Working with selections and cell references

Selection as reference. Whatever you have selected in Excel is sent as a reference. So you can select and write "format this as currency". The sidebar footer always shows the range the add-in currently sees, for example Sheet1!E1:F7. Clicking it jumps there, so you can check before approving that it means the right range.

Reading back in the workbook. With every request the model receives a description of the workbook. For "why does B4212 calculate incorrectly?" that is not enough. The model then requests a specific range, with formulas instead of values if needed. Beforehand the sidebar shows Liest in der Mappe nach (reading in the workbook) and the range. Limits: at most two read rounds per request and 20,000 cells per range. Each round is another model pass, which you will notice during a cold start.

Clickable cell references. When the answer names a cell or range, such as D2:D40 or TaxRates!B2, the reference is a button. Clicking it switches to the sheet and selects the range. This works for cells, ranges and whole columns (C:C) on every sheet. Only what the model explicitly marks as a reference, and what exists in your workbook, becomes clickable. That way "DIN A4" or the key "F1" does not turn into a wrong jump. Nothing inside formulas or source code is linked.

Questions back

If a task depends on a decision that is yours (period, tax rate, which sheet), the model offers two to five clickable options. The recommended one is at the top and preselected.

• 1–5 to select, Enter to confirm, Esc to skip.
• Etwas anderes (something else): type your own answer.
• Entscheide du (you decide): the model makes an assumption itself and states it in the answer.

A click only selects; Weiter (continue) submits. That way a stray click while switching between sheet and sidebar does not become an answer. A question back is not an approval: whether anything is written is decided solely by the "Freigabe" selector.

Macros: source code to copy

The add-in cannot run VBA macros. That is down to the Office interface for add-ins: it runs sandboxed and also where VBA does not exist (Excel on the web, iPad). No Excel add-in can run macros.

If you ask for a macro, the add-in generates VBA or Office Script source code. The macro card shows:

• a copy button and line numbers,
• where the code belongs: an event procedure such as Worksheet_Change only runs in the code window of its sheet. In a normal module it is never triggered, and there is no error message.
• the procedure names you start it with,
• what stands out: a missing Option Explicit, swallowed errors (On Error Resume Next without being reset), a decimal comma (VBA uses the dot) and umlauts in strings. The VBA editor uses the system code page, not UTF-8, so umlauts can break when pasted. The add-in then names the safe route (ChrW(228) for ä).

You paste it in yourself (VBA editor: Alt+F11). Excel on the web and the iPad have no VBA editor; there the add-in suggests an Office Script.

Changing existing macros: with Makro bearbeiten (edit macro) at the bottom of the sidebar you paste in existing source code. The model can explain, review and change it, and returns the new version in full. While source code is pasted in, it goes to the model with every request. Leeren (clear) removes it. It is not stored and is gone when you close the sidebar.

Why the clipboard? The Excel JavaScript API does not hand out the VBA project on its own. To read a macro ourselves, we would have to upload the whole file. Also, an .xlsm stores every macro both as source and precompiled. If only the source is swapped from outside, the editor shows the new code and runs the old one. When you paste it yourself, Excel recompiles.

For automation that should run by itself, Office Scripts is Microsoft's successor to VBA. It needs a business licence with OneDrive for Business and has no events such as Workbook_Open or Worksheet_Change. Scripts only start manually or from Power Automate.

What is sent to SovrGPT

The file is not uploaded. With every request, a description of the workbook goes to the model you chose:

• file name, sheet names, used ranges, row and column counts
• column titles and detected column types
• existing formulas as patterns (=B2*C2, 249×) rather than one by one
• up to five sample rows per sheet, switchable via Beispieldaten mitschicken (send sample data)

On top of that come your instruction, the selection, ranges the model reads back, and any pasted macro source. Was wird gesendet? (what is sent?) shows the complete text that goes to the model. Because the description grows with the structure and not with the data, a workbook with a million rows costs about as much as one with a hundred.

Storage and AI processing take place in EU data centres. The exception is web search.

Web search (provider in the USA). The Websuche (web search) toggle is on by default. If the model is missing a fact, such as a current tax rate, it sends a search term to Brave Search (Brave Software, Inc., USA). This is text formulated by the model, not the workbook. It can still contain terms from your task or your sheet. Every search then appears with its search term in the conversation. If you switch web search off, the model gets no search tool and tells you when it cannot look something up.

More on locations and service providers: GDPR & compliance and the privacy policy.

Signing in

On first start you sign in with your SovrGPT account. The add-in receives an access of its own. It applies only to you, to one organisation and only to the Excel sidebar, and it can be revoked individually. Your API key is not used for this.

If you belong to several organisations, the add-in works with the one that was active when you signed in. To switch, change the organisation in SovrGPT, then sign out in the sidebar and sign in again.

Installation in detail

The manifest, the add-in's XML description, is at https://sovrgpt.com/xl/manifest.xml.

Centrally for the whole organisation (recommended)

IT enters the manifest address once. After that, all assigned users have the button in Excel, with no step of their own and no SmartScreen warning.

Microsoft 365 admin center → Settings → Integrated apps → "Upload custom apps" → Office Add-in → manifest URL https://sovrgpt.com/xl/manifest.xml → Validate → Assign users → Finish.

• Choose "Fixed" as the deployment type. The IT page explains why.
• Publishing on AppSource is not required.
• Updates need no re-entry; the code sits on our server.
• It can take up to 72 hours until the add-in appears for everyone.

Prerequisites are Exchange Online with an active mailbox and Entra ID. Microsoft 365 Apps for Business is not enough (no Exchange Online), and MSI or perpetual versions of Office are not supported. In a pure LTSC environment without a Microsoft 365 tenant, use the single-machine route.

All details for administrators, including network allowances, group policies and the government-cloud special case, are on a separate page you can pass on: Deploying the Excel add-in for IT (https://sovrgpt.com/en/docs/excel-addin-it).

A single Windows machine

Instructions to pass on are at sovrgpt.com/en/excel (German: sovrgpt.com/excel). The files directly: SovrGPT-fuer-Excel-installieren.cmd and SovrGPT-fuer-Excel-entfernen.cmd. The steps are above under Installing.

The file places the manifest in your user profile (%LOCALAPPDATA%\SovrGPT\Excel\) and writes a single value under HKCU\Software\Microsoft\Office\16.0\WEF\Developer. It needs no administrator rights, Trust Center settings or folder shares.

• Windows SmartScreen warns ("Windows protected your PC"), as with every file of this type from the internet: More info → Run anyway.
• The file cannot be sent by e-mail. Outlook blocks .cmd, .bat, .reg, .exe and .msi (level 1 block list). Share the link, not the file.
• Removing: double-click SovrGPT-fuer-Excel-entfernen.cmd, again without administrator rights. It deletes the registry value and the folder %LOCALAPPDATA%\SovrGPT\Excel. Then restart Excel.

Checksums. Office add-ins are not signed (see below). To check that you have our file, run Get-FileHash <file> in PowerShell:

We check these values automatically against the shipped files with every change.

Excel on the web

This requires a workbook in OneDrive or SharePoint.

1. Open sovrgpt.com/xl/manifest.xml in your browser and save it with Ctrl+S. Do not open it in Excel.
2. Open the workbook in Excel on the web.
3. Home → Add-ins → More Add-ins → My Add-ins → Upload My Add-in, select the saved file, Upload.

Excel on the web remembers the add-in in the browser. After clearing browser data, or in a different browser, upload it again. To remove it: Home → Add-ins → My Add-ins → context menu → Remove.

Mac without a Microsoft 365 tenant

Save the manifest as for Excel on the web and put it in this folder (create it if it is missing):

~/Library/Containers/com.microsoft.Excel/Data/Documents/wef

After restarting Excel, the add-in is under Insert → Add-ins → My Add-ins → Developer Add-ins. We have not tested this route ourselves. It follows Microsoft's instructions for sideloading on macOS; feedback is welcome.

When the manifest changes

Improvements to the add-in arrive without any action on your part, because the code sits on our server. If the manifest itself changes, for example for a new ribbon button, we announce it in advance. The last change was in August 2026.

Why there is no certificate

Office web add-ins are not signed. Unlike VBA macros or COM and VSTO add-ins, there is no Authenticode procedure. An add-in is a web page plus an XML description. The certificate that matters is the TLS certificate of sovrgpt.com.

Supported Excel versions

The add-in runs from Excel 2016 onwards. When you send a request, it tells the model what your version can do, so the plan contains only suitable steps. If one slips through anyway, it is rejected with the required Office version named, and the rest of the plan runs normally.

"Derived" means: from Microsoft's availability table for the API sets we use, not from a test on that exact version.

Limits

• Large workbooks: at most 20,000 cells per operation and 50,000 per plan. Split larger tasks. The sidebar tells you when a change was too large.
• No deleting sheets, no sheet protection. Excel cannot undo either. Sheet protection even clears the whole undo buffer, and our own undo with it.
• No running macros, see Macros.
• Cancelling only disconnects. While the model is working, Abbrechen (cancel) ends the request and your workbook stays unchanged. Whether the provider discards the computation it started, we cannot see. While the plan is being written into the workbook, the button is not offered, so no half-applied plan is left behind.