What SumOffice is

SumOffice is an office platform you embed in your product. Your users open and edit Word documents and Excel spreadsheets inside your application, under your name. Files never leave for someone else’s office suite or someone else’s cloud.

The platform consists of two engines and a shared embedding model:

Engine	Files	What it gives	Documentation
SumDoc	DOCX	A ready-made document editor: opens a Word file, shows pages, lets you edit, saves and reopens. In the browser, the full editor opens on your domain. There is also a lightweight surface for trying out embedding — it can do less.	SumDoc section
SumSheet	XLSX	A ready-made spreadsheet editor: grid, formulas, edit history, import and saving. Large workbooks open because only what’s needed is kept in memory. It can calculate both on your server and right in the user’s browser — with no server at all.	SumSheet section

A third editor — for presentations — is in development; the public beta is planned for December 2026. It can’t be downloaded yet, and PPTX compatibility, platforms, and speed are not promised.

The main formula

The input is your product, your brand, and your documents. The output is a Word and Excel editor inside your product, under your name: editing DOCX and XLSX, saving, automation, agent work, a security boundary, and a verifiable list of capabilities. Part of the list is already public: 13 spreadsheet formats and what you can do with each file type in documents.

What exactly is promised

SumOffice doesn’t copy Microsoft Office in full and doesn’t promise to be better than it. The promise is different: on your documents and your operations, the editor does the same as Word and Excel, and this is verified at acceptance. On top of that — what Office doesn’t have: the editor lives inside your product, under your control, with saving, automation, and verifiable acceptance. More — Feature parity.

Three things worth understanding right away

1. Who owns what. You own the product, the brand, user sign-in, storage, and the business process. SumOffice is responsible for what happens to the document inside. The boundary between them is narrow and fixed by the contract — see Customizing under your brand.

2. A document has one owner — the core. The document model, formulas, history, and file writing live in the platform’s core. The screen only shows the document and passes to the core what the user wants; it doesn’t write the file itself.

3. A refusal is better than silent corruption. If an operation can’t be performed, the answer with the reason arrives before the file changes. There is no such thing as a half-corrupted file. For developers — how to read an SumDoc response and how an SumSheet response is structured.

Where to start

If you don’t know where to start, see how to read this documentation: it has routes by role.

Role	First page
Executive, product, presales	What you get
Architect	SumDoc architecture and SumSheet architecture
Integrator	SumDoc quick start or SumSheet quick start
Security team	Security and operations
An AI assistant reading on your behalf	AI tools and MCP
An agent that edits your file	Product MCP server