Creating and editing documents
Have Word, Excel, PowerPoint and PDF files created, or change your own files in the chat with letterhead, formulas and formatting intact.
The model can give you finished files instead of text to copy. And it can change a file you attached: letterhead, formulas, tables and formatting stay as they are, because it edits the real file rather than rebuilding it.
Writing and editing a document in the chat
Ask for a draft (concept, report, letter, offer) and a document opens beside the chat. Edit it directly like in a word processor, with headings, lists and tables. The model revises single passages on request: select a passage, press Edit with AI and write in the chat what should change. For larger changes a message without a selection is enough: "Shorten the second section and make the tone more factual."
Every change, yours and the model's, is a version. Under Versions you see who changed what and when, and Restore brings back an earlier one. The model always works on the text you see, even if you have just changed something yourself. Done? Download exports the document as Word, PDF or Markdown. A viewer of a shared chat can download the document but not change it.
Have a new file created
Ask for the file
Say what you need and name the format, for example:
Create a quote for Holzwerk Brunner GmbH as a Word file: annual accounts 2026, hourly rates as in the attached Fee Schedule 2026.
Wait a moment
While the file is being made you see Creating document…, Creating spreadsheet… or Creating presentation…. The answer itself stays short; the content is in the file.
Download the file
The file appears under the answer with its name and size. Click it to download it.
| You need | The model creates | Good to know |
|---|---|---|
| Letter, quote, report, minutes | Word (.docx) or PDF | Word if you will keep working on it, PDF for the final version. Headings, lists and tables are carried over. |
| Table, budget, list | Excel (.xlsx) | Totals and calculations arrive as real Excel formulas. The header row is bold and frozen. From an attached workbook the model takes the data directly instead of retyping it. |
| Presentation | PowerPoint (.pptx) | With a title slide and different slide types: bullet points, key figures, tables, timeline, charts, plus speaker notes. Every slide carries an action title, a descriptor for the exhibit and a source line; illustrative numbers are tagged. Attach a reference deck and ask for "the style of this file" and the new presentation takes its colours and fonts (not its slide masters). |
If your workspace uses pseudonymisation, the model only sees names as placeholders. Custodos still writes the real values into the file, so the quote is addressed correctly.
Analysing large spreadsheets
Attach a large Excel file, say a data list with thousands of rows, and the model does not read every cell. It receives an overview of the workbook (sheets, columns, types, row counts, a few sample rows) and fetches what it needs on demand: individual ranges, or aggregates such as sum, count and average per group, which Custodos computes rather than the model. That keeps the answer fast and the credits small.
If you want an Excel file from it, Custodos copies the source data into a "Data" sheet and writes the aggregates as formulas that point at that data. The formulas are computed when the file is opened in Excel. Best ask in two steps: first the analysis in the chat, then the file.
Reviewing and building Excel models
A calculation model is more than a table. Ask for a model review and the model first gets an overview of the workbook: sheets, named ranges, external links, whether the formulas in a column are built the same way throughout or deviate in the middle, which formulas carry hidden numbers ("×1.19" instead of a named assumption), error values and circular references. Only then does it read the areas it flagged and write the findings with location, problem, impact and proposal. Nothing is recalculated; Excel does that when the file is opened.
Ask for a new model and the workbook follows the usual conventions: a first "Readme" sheet with purpose, assumptions, sources and checks, every assumption in its own named cell, inputs in blue on a light background, formulas in black, no numbers inside formulas, check formulas that come to zero. Say which assumptions and scenarios the model needs, and check the assumption cells in the finished file.
Have your own file edited
Attach a PDF, Word or Excel file directly (with the plus sign, by dragging or by pasting) and describe the change. You get a new file, usually with "-bearbeitet" added to its name. Your original stays unchanged in the chat.
Attach the file
Upload the file as described in Attaching files and images. Files up to 4 MB can be edited.
Describe the change
For example: "In the New Client Checklist, replace every 2025 with 2026 and add a point about the privacy notice after the identification section."
Download the result
You see Editing PDF…, Editing Excel file… or Editing Word file…. The new file then appears under the answer.
PDF: pages
The model can keep or remove pages, change their order, rotate pages by 90, 180 or 270 degrees and append other attached PDFs at the end. Example: "Remove page 3 and append the form at the end." It cannot change the text on a PDF page. If you ask for that, the model writes a new document without the original layout and tells you so.
Excel: cells
The model sets values and formulas, clears ranges and adds rows at the end. Formatting, other sheets and charts stay as they are. Every formula is checked before it is written to the file: missing sheets, references to the cell itself, unknown functions and unclosed brackets are caught. Excel recalculates the formulas when the file opens. Inserting or deleting rows or columns is not possible, because it would break references. More in Spreadsheet analysis.
Word: text
The model replaces wording, inserts paragraphs, deletes paragraphs and appends sections. Replacements match the exact wording everywhere in the document, including tables, headers and footers. Styles, tables, images and headers are kept.
If you ask for tracked changes, every change comes back as a revision you can accept or reject one by one in Word. The author shown there is the platform's name, for example Custodos. The model cannot move text or change the formatting of existing text. More in Reviewing and revising contracts.
PowerPoint: text, slides and notes
The model changes text on the slides, removes slides and writes speaker notes without touching the design: masters, layouts, charts and images stay as they are. Say for example "change the title on slide 4 to … and delete slide 7". Adding slides or restructuring a layout is not possible this way; for that the model builds a new presentation.
Keep working with a generated file
A file the model created or edited in this chat can be changed again later. "Also change the date in the document" applies to the newest version, not to your original.
Save a brain document back
If you open a Word or Excel document from a brain with Edit in chat, a Save to brain button appears next to the edited file. One click saves it as a new version of the document. You need edit rights in the brain for this. More in Keeping a brain up to date.
What cannot be edited
- Files from Google Drive, Microsoft 365 or Outlook: they only reach the chat as text. Download the file and attach it directly.
- Legacy formats (.doc, .xls, .ppt) and .ods: the model can only read these.
- Scanned PDFs without a text layer: they cannot be attached in the chat.
Best practices
- Provide the source, such as the Fee Schedule 2026 as an attachment or from a brain, instead of relying on figures from the model's memory.
- Say what must stay unchanged: "Only adjust the amounts in column D, nothing else."
- For contracts, ask for tracked changes and review every change in Word.
- Check figures and formulas in the finished file. The check catches broken formulas, but not a wrongly chosen cell.
Frequently asked questions
The chosen model has no tools. Open the model picker and choose a model whose info card does not say "No web or brain search, and it creates no files."
No. You always get a new file, usually with "-bearbeitet" added to its name. The original stays attached to the chat.
You asked for a text change in a PDF. That is only possible by writing a new document, without the original layout. If you have the Word file the PDF was made from, attach that and have the text changed there.
Next steps
Formats, sizes and what happens to attached files.
Reviewing and revising contractsA contract back with tracked changes, step by step.
Spreadsheet analysisAnalyse tables and have cells changed with checked formulas.
Keeping a brain up to dateEdit originals in chat and save them as a new version.