Excel add-in

The SovrGPT add-in sits in Excel as a sidebar. You describe what should happen to the workbook; the add-in proposes a list of changes. How often you are asked is your setting — out of the box every proposal waits for your approval, and on request it runs fully automatically (see approval mode).

You pick the model at the top of the sidebar. Not all of the platform's models are listed there, only those suited to spreadsheet work — a model tuned for source code does not help you build a readable evaluation. Every entry shows its role first and the model behind it, for example All-rounder · Qwen 3.8 27B.

An entry marked "instant" runs in a European partner data centre and is available without any waiting time. The others run on our own GPUs in the EU — more sovereign, but with a cold start when no compute node happens to be running (see limits). Both are EU operation; the difference is whose card does the computing.

What it can do

• Build formulas — mark-ups, sums, lookups, key figures. Wherever a formula is possible, the add-in writes the formula and not the computed number. You see the calculation and can change it.
• Create and restructure sheets — new worksheets, insert or delete rows and columns, freeze panes.
• Write values — entire ranges in one go.
• Format — number formats, font, fill, alignment, borders, column widths and row heights, merge cells.
• Conditional formatting — colour scales, data bars, traffic-light icons and rules on cell values or text. This is the formatting that makes a table not just pretty but readable: it shows anomalies without anyone having to look for them.
• Sort, filter, group, hide — multi-level sorting, set an AutoFilter, fold away helper columns instead of leaving them standing.
• Data validation — pick lists and value ranges, so that typos never arise in the first place.
• Named ranges and comments — for formulas you will still be reading in a year's time.
• Print setup — print area, portrait or landscape, fit to one page wide, repeat the header row on every page.
• Build tables and charts from existing data.
• Generate VBA and Office Script source code — to copy, with a review and installation instructions. You can paste existing macros in to have them changed. See below.
• Ask questions instead of guessing — for a genuine decision the model presents you with clickable options. See below.
• Read back in the workbook and cite cells clickably — every cell reference in the answer is a button that jumps exactly there. See below.
• Look things up on the web that are not in the workbook — current tax rates, exchange rates, market figures. The sidebar shows the search term and the sources above the answer, so a looked-up number can be told apart from an invented one. Switchable via the "Web search" toggle.

Reading back in the workbook

When you send a request, the model receives a description of your workbook — sheets, columns, formula patterns and the first rows as a sample (see What is sent to SovrGPT). For "build me a column" that is enough. For "why does B4212 calculate incorrectly?" it is not.

The model can therefore read back selectively: it requests a range, the add-in reads it via Excel and sends it along with the next request. Meanwhile the sidebar says "reading in the workbook" with the range below it — so you see beforehand which excerpt is going out.

On request it reads the formulas instead of the values. That is exactly what it takes to explain a calculation error.

ℹ️ Limits, so that it does not cost you waiting time: at most two read rounds per request and at most 20,000 cells per range. Every round is a complete additional model pass — noticeable with a model that has a cold start. If the model requests too large a range, it is refused and told to take a smaller one.

The file is not uploaded for this either. Only the requested excerpt goes out, and only to the model you chose.

Select the cells in question

Whatever you have selected in Excel goes along as a reference. Instead of describing where something is, you simply select it and write "format this as currency" or "sort this by the second column". The add-in then knows what "this" is.

The footer of the sidebar always shows which range the add-in currently sees — for example Sheet1!E1:F7. The display follows your selection.

ℹ️ Click the display if you are unsure. It jumps to exactly the range the add-in means. If it differs from what you expected, you notice before approving a change.

Cell references in the answer are clickable

When the add-in names a specific cell in its answer — "the sum column calculates in D2:D40", "the tax rate is in TaxRates!B2" — that reference is a button. Clicking it switches to the sheet and selects exactly that range. So you do not have to hunt for the cell to check whether the statement holds.

This works for individual cells (B12), for ranges (B2:D40) and for whole columns (C:C), on every sheet of the workbook.

ℹ️ Why not every reference is clickable. Only what the model explicitly marks as a reference becomes clickable — and only if the named sheet really exists in your workbook. Both are deliberate: "DIN A4", "B2B customers" or the key "F1" look like cell references to an automatism, and a button that jumps you somewhere arbitrary in your workbook would be worse than none. Inside formulas and source code nothing is linked — there the reference stays as it is.

Cancelling

While the model is working, a Cancel button sits next to the waiting line. It ends the request; your workbook stays unchanged.

ℹ️ What the button honestly does: it disconnects from the model. Whether the provider then actually discards the computation it started is something we cannot see — which is why it says "cancelled" and not "stopped".

While something is already being written into the workbook (or a change is being reverted) the button deliberately does not exist: an abort in the middle would leave a half-applied plan behind. Those steps run locally and take seconds.

Questions back: the model asks, you click

Sometimes a task hinges on a decision that is yours — which period the evaluation should cover, which tax rate applies, which of three sheets is meant. The model used to write running text in such cases that you had to answer. Now it presents you with clickable options:

• Two to five options, each with half a sentence on what it means.
• The one the model recommends is at the top and preselected — if it fits, it is one click on Continue.
• Keyboard: 1–5 to select, Enter to confirm, Esc to skip.
• "Something else" — if no option fits, you type your own answer.
• "You decide" — you do not have to answer. The model then makes an assumption itself and writes it into its answer, so you can follow it.

Your choice stays in the conversation. The model then continues within the same request — you do not have to repeat your ask.

ℹ️ A click selects, it does not yet submit. That is deliberate: in Excel you click back and forth between the sheet and the sidebar constantly, and the first click back into the sidebar lands wherever the pointer happens to be. An answer submitted by accident cannot be taken back.

ℹ️ A question back is not an approval. Whether your plan is applied is decided solely by the "Approval" selector (see below). The model is not allowed to ask you for permission on top of that and thereby override your setting.

Thinking: the effort is adjustable

Some models can think before answering — they work the task through silently first and then write the plan. For simple tasks that is wasted time; for a tricky formula it is often the difference.

If the selected model shows a "Thinking" control at the bottom edge, you can steer it: off (fastest answer, default) or brief / medium / thorough.

ℹ️ The control only appears for models where we have measured the effect. A switch that does nothing would be worse than no switch — so we do not show it for models that silently discard the value. For models that always think, the off position is missing.

What it costs you: thinking costs time and counts as generated text in the billing. The add-in automatically raises the answer budget so that the chain of thought does not crowd out the plan.

What it cannot do: run macros

The add-in cannot start VBA or macros. That is not a gap in our implementation but a property of the Office extension interface: add-ins run in a sandbox and in environments where VBA does not exist at all (Excel on the web, iPad). The Excel JavaScript API therefore contains not a single class for VBA projects.

This applies to every vendor. Anthropic's Claude for Excel lists "Macros and VBA operations" under Unsupported capabilities itself.

What we do instead: if you ask for a macro, the add-in generates the source code and shows it to you — VBA or an Office Script. You have to copy and paste it yourself (VBA: Alt+F11).

The macro card makes more of it than a text box:

• Copy button — one click, the whole source code on the clipboard.
• Where it belongs. An event procedure such as Worksheet_Change runs only in the code window of that specific sheet; in a normal module it is never triggered — and without an error message. The add-in detects this and says so.
• What starts it — the contained procedure names are listed.
• What stands out — a missing Option Explicit, swallowed errors (On Error Resume Next without being reset), a decimal comma (in VBA the dot is the decimal separator) and umlauts in string literals: the VBA editor works with the system code page, not with UTF-8, so they can be damaged on the way through the clipboard. The add-in then names the safe route (ChrW(228) for ä).
• Line numbers — the notes refer to lines, and without numbers you cannot find them.
• The platform truth. If you are working in Excel on the web or on an iPad, there is no VBA editor there at all. Instead of recommending Alt+F11, the add-in says so — and suggests an Office Script.

Changing existing macros: via "Edit macro" at the bottom edge you paste in existing source code (select and copy it in the VBA editor). The model can then explain, review and change it, and returns the changed version in full.

🔒 Why through the clipboard and not automatically? Because the more convenient route would break our promise: to read your macro ourselves we would have to upload the whole file — the Excel JavaScript API does not hand out the VBA project separately. The pasted source code goes to the model, your file stays where it is. It is not stored anywhere and is gone as soon as you close the sidebar.

The detour has a second advantage: an .xlsm stores every macro twice — as source code and as a precompiled version. Anyone who edits a file from the outside and swaps only the source code ends up with a workbook that shows the new code in the editor and runs the old one. When you paste it in yourself, Excel recompiles, and the problem does not exist.

ℹ️ For automation that really has to run, Office Scripts is Microsoft's intended successor to VBA. It requires a business licence with OneDrive for Business. ⚠️ Office Scripts, however, know no events — there is no counterpart to Workbook_Open or Worksheet_Change; scripts are only started manually or from Power Automate.

Preview, approval mode and undo

Every proposal appears as a plain-language list — one line per change, with the affected range. Clicking a line jumps there in the workbook.

How often you are asked is your decision — via the "Approval" selector at the bottom of the sidebar:

Three rules apply in every mode:

1. A proposal in which the review rejected individual steps always waits for you — otherwise what gets written would not be what the model proposed.
2. Every automatic application is explicitly marked as automatic in the sidebar.
3. A proposal containing a formula that would send data to the internet always waits for you — even in "fully automatic" mode.

Formulas that send data outwards

Excel has functions that fetch an internet address by themselves — without anyone clicking. =IMAGE(...) fetches an image, =WEBSERVICE(...) an arbitrary response. If part of your data is in that address, it has thereby reached the recipient of the address.

Exactly this has been demonstrated against a competitor: an instruction hidden in an imported third-party file got the assistant to write such a formula, and the confidential figures went to a foreign server.

The add-in therefore checks every formula in a proposal — not just the first one in the preview. If it finds one, then:

• the proposal waits for you in every approval mode,
• the warning stands permanently visible at the top, never collapsed,
• and it shows the formula verbatim including the cell and the address — not just "a cell is being set". Invisible control characters are made visible (<U+200B>), because such an address can otherwise hide in exactly those.

None of this is forbidden: fetching an image from the internet into the workbook is a legitimate wish. You should merely be able to make the decision.

⚠️ Bear in mind with "fully automatic": cell contents can contain instructions that influence the model (prompt injection). The default "confirm every change" is therefore the safe choice for workbooks from a third party.

Everything is applied in one go. You can take it back with the Undo last change button in the sidebar — including after an automatic application.

⚠️ What the undo covers: values, formulas, number formats, column widths as well as deleted or inserted rows and columns are saved before the change and fully restored.

What it does not cover: pure appearance — font, fill, alignment, borders. Those operations are marked in the preview with "Ctrl+Z only". The reason is a complete format dump that older Excel versions (2019) do not offer. We would rather mark that than promise an undo that then does not come.

🔴 A special case caused by Excel itself: if a sheet is renamed or moved, Excel on Windows and Mac deletes the entire Ctrl+Z chain — including everything you did by hand beforehand. That is down to Excel, not the add-in (it does not happen in the browser). If a proposal contains such a step, the note stands clearly visible in the preview. Our own undo for values and formulas continues to work.

Older Office versions

The add-in runs from Excel 2016 onwards. Older Office versions can do less: data validation, AutoFilter, comments and print setup, for example, require Office 2021 or newer.

You do not have to worry about this. When you send a request, the add-in tells the model what your Excel version supports — so proposals contain only steps that will actually run for you from the outset. If one slips through anyway, it is rejected on application and named to you in plain language together with the required Office version; the rest of the plan continues normally.

What is sent to SovrGPT

The file is not uploaded. What is sent is a description of the workbook:

• File name, sheet names, used ranges, row and column counts
• Column titles and detected column types
• Existing formulas as patterns (=B2*C2, 249×) instead of individually
• On request up to five sample rows per sheet

The "Send sample data" toggle at the bottom switches the sample rows off. "What is sent?" shows you the complete text that goes to the model — not a description of it, but the text itself.

Because the description grows with the structure and not with the data, a workbook with a million rows costs practically the same as one with a hundred.

One exception you need to know about: web search. If the "Web search" toggle is on and the model decides it is missing a fact, a search term goes to Brave Search — not the workbook, not the digest, but a text formulated by the model that may contain terms from your task. Every executed search subsequently appears in the conversation with its search term, so you can see afterwards exactly what went out. If you do not want that, switch the toggle off: the model is then not offered the search tool at all and tells you that it cannot look something up.

Signing in

On first start you sign in with your SovrGPT account. In doing so the add-in receives an access of its own that applies exclusively to the Excel sidebar.

That is deliberately not your API key: an API key applies to the whole organisation and to every interface. The add-in access applies to you, to one organisation and only to this one function — and can be revoked individually.

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

Installation

The manifest is at https://sovrgpt.com/xl/manifest.xml.

🔴 Do NOT open the file in Excel and do not double-click it. Excel then takes an XML file for an XML expansion pack (a "smart document" from Office 2003) and reports that the file could not be installed because a problem with the security certificate was found, and that the XML expansion pack may not work as expected.

(German original: „Diese Datei konnte nicht installiert werden, da ein Problem mit dem Sicherheitszertifikat festgestellt wurde. Das XML-Erweiterungspaket wird möglicherweise nicht wie gewünscht funktionieren.")

That message has nothing to do with the add-in. XML expansion packs have to be signed — Office add-ins are never signed. If you see it, you have taken the wrong route; the right ones are below.

① Companies and public authorities: central deployment — the recommended route

Your IT enters the manifest address once, and afterwards all users have the button in Excel — without a single step of their own and without the SmartScreen question from ②.

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.

• Publication on AppSource is not required for this.
• Choose "Fixed" as the deployment type. ⚠️ For Optional and Available there has been an open Microsoft incident since 2026-07-28 affecting Excel Desktop and Excel on the web.
• Updates require no further admin action. The code sits on our server; the manifest only points at it.
• ⏱️ Up to 72 hours until it appears for all users.

🔴 Prerequisites that can become knock-out criteria: Exchange Online with an active mailbox and Entra ID are mandatory; Microsoft 365 Apps for Business is not sufficient (no Exchange Online), and MSI/perpetual versions are not supported (Outlook excepted). A pure LTSC environment without a Microsoft 365 tenant cannot take this route — there ② is the right one.

📄 To pass on to your IT: Deploying the Excel add-in for IT — a page an Office administrator can work through without follow-up questions: the steps in the admin center, the prerequisites as a knock-out list, the two network allowances, the check command for the group policy, the special case of the public-sector cloud and the data protection details. Passing it on means passing on the link — https://sovrgpt.com/en/docs/excel-addin-it.

② A single Windows machine: one file, one double-click

👉 The ready-made instructions to pass on are at sovrgpt.com/en/excel (German: sovrgpt.com/excel). One button, four steps, no document. This is the link you share with colleagues — the installation file itself cannot be delivered by e-mail (see below).

1. sovrgpt.com/en/excel → Download the installation file → double-click. (Direct: SovrGPT-fuer-Excel-installieren.cmd — to remove it, SovrGPT-fuer-Excel-entfernen.cmd.)
2. Close Excel completely — every window — and reopen it.
3. 🔴 In Excel, click Home → Add-ins, select SovrGPT für Excel there and press Add.
4. Done. The Open assistant button is from now on permanently in the Home tab, in the SovrGPT group.

No Trust Center, no folder share, no administrator rights. 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.

⚠️ Windows SmartScreen will warn ("Windows protected your PC") — that applies to every file of this type downloaded from the internet. More info → Run anyway. If that is uncomfortable, take ①.

🔴 The file cannot be delivered by e-mail. Outlook blocks .cmd, .bat, .reg, .exe and .msi on the level 1 block list — the recipient can neither open nor save it. Share the link, not the file.

Removing it again

SovrGPT-fuer-Excel-entfernen.cmd — likewise a double-click, likewise without administrator rights. It reverses both: the registry value and the folder %LOCALAPPDATA%\SovrGPT\Excel. Then close Excel completely and reopen it; the sidebar is gone.

With central deployment (①), IT removes the add-in in the admin center → Integrated apps; users have to do nothing. In Excel on the web (③) you remove it via Home → Add-ins → My add-ins → context menu → Remove.

Checksums

Since there is no certificate (see below), these are the only values against which you can verify that you have our file. In PowerShell: Get-FileHash <file>.

ℹ️ These values are checked against the shipped files on every test run (tests/xl-installer-integrity.test.ts). A checksum that silently goes stale would be worse than none at all.

③ Excel on the web: the fastest way to try it out

This requires a workbook in OneDrive or SharePoint — there is no Trust Center and no share for it.

1. Save the manifest as a file. Excel on the web requires a file from your hard disk, not an address. Open sovrgpt.com/xl/manifest.xml in your browser and save the page with Ctrl+S. ⚠️ Do not open it in Excel — that is exactly the route that triggers the certificate message above.
2. Open the workbook in Excel on the web.
3. Home → Add-ins → More Add-ins → My Add-ins → Upload My Add-in.
4. Select the saved file → Upload.

ℹ️ This does not last forever. Excel on the web remembers an add-in uploaded this way in the browser's storage. After clearing browser data, or in a different browser, you have to upload it again. For permanent use, ① is the right route.

④ A single Mac without a Microsoft 365 tenant

Route ② is Windows-specific — it writes a registry value, and the registry does not exist on macOS. The counterpart is a folder: place the saved manifest (step 1 from ③) here and restart Excel:

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

If the wef folder does not exist, create it. The add-in is then under Insert → Add-ins → My Add-ins → Developer Add-ins.

⚠️ We have not carried out this route ourselves. It comes from Microsoft's documentation on sideloading under macOS. If you have a Mac to hand and try it: feedback welcome — then next time this will say "measured".

When the manifest changes

The code of the add-in sits on our server — improvements arrive without you doing anything. That does not apply to the manifest itself (the XML description with the ribbon buttons and permissions):

We announce such cases in advance. They are rare: the manifest last changed in August 2026.

Why there is no certificate

Office web add-ins are not signed. Unlike VBA macros or old COM/VSTO add-ins there is no Authenticode procedure, no certificate to buy and no approval to obtain — an add-in is a web page plus an XML description.

The only certificate that counts is the TLS certificate of the domain, and sovrgpt.com brings that along.

Supported Excel versions

The add-in requires only the smallest Excel API set and therefore loads on older perpetual versions too. Anything beyond that it checks at runtime and leaves out if it is missing.

ℹ️ Why the last column does not say "measured" everywhere. The add-in asks at runtime what your Excel version can do and leaves out what is missing — so the "derived" rows follow from Microsoft's own availability table for the API sets we use, not from a test run on exactly that version. Where we have not run it ourselves, it says so. We prefer a row that names its origin over an assurance that, in case of doubt, nobody checked.

On the iPad there is the additional point that there is no ribbon for add-ins: the sidebar has to be surfaced through a central deployment.

Limits you should know about

• Large workbooks: per operation the add-in writes at most 20,000 cells, per plan 50,000. You split larger tasks into several steps — the sidebar tells you when a change was too large.

• Cold start — but no longer with every model. An entry marked "instant" runs in a European partner data centre and answers with no lead time. With the models on our own GPUs the first answer can take several minutes if no compute node happens to be running; every one after that is fast. The note under the model name gives the measured order of magnitude. The sidebar shows the elapsed time and, from about a minute onwards, also what it may be due to — it estimates no remaining time and never claims a model is ready. That simply cannot be determined reliably in advance, and a false assurance would be worse than none.

• There is no tool for deleting a sheet and none for sheet protection. Excel cannot undo either — sheet protection even clears the entire undo buffer and would thereby destroy our own undo as well. So we do not offer it.

• Not everything runs on every Excel version. The add-in checks this beforehand and tells you rather than failing at it:

  Feature	From
  Conditional formatting, sorting, merging, row height, hide/show, named ranges	Office 2019
  Data validation, AutoFilter, print setup, grouping, comments	Office 2021

  On Office 2019 the operations in the second row are rejected with a note; the rest of the plan runs through normally.

• Cell contents are data, not commands. If a cell contains text phrased as an instruction, the add-in does not execute it but points it out.