Word add-in development is a narrow speciality with unusual tooling, and the people who know the document format tend to work for the vendors selling document products. That is the gap this page exists for.
We build document software you own, rather than a subscription to somebody else’s.
Word Add-In Development with Office.js
An add-in puts a panel inside Word itself, on desktop and on the web, so your team never leaves the document. Typical jobs: pulling matter data in from a system of record, applying house style in one action, validating a draft against your own clause rules.
Three things are worth knowing before you commission one.
Office.js is its own model. Asynchronous, sandboxed, and different from the old COM automation approach. Some requirements suit a different route entirely, and scoping is where that gets settled.
Deployment is a real decision. Central deployment through the Microsoft 365 admin center covers most internal tools. AppSource is for commercial distribution and carries its own review timeline.
Desktop and web behave differently. Enough that anything shipping to both gets tested on both, and the quote says so.
Beyond the Add-In
DOCX and OOXML manipulation. Working on the file format directly rather than driving Word through automation. Nothing has to be open, no machine needs Office installed, and ten thousand documents cost roughly the same per file as one.
PDF generation, editing and processing. Fixed-layout output, form filling, splitting and merging, stamping, and extracting text and tables back out.
Template systems and merge at scale. A merge that runs as a scheduled job against a database instead of as somebody’s Tuesday afternoon.
Document data extraction. Structured fields pulled out of invoices, contracts, statements and forms, into a system that can act on them.
When Building Earns Its Cost
Products fit standard processes well, and where one fits yours it will be the cheaper answer.
Building pays where your process has a shape the product cannot hold, where documents stay inside your network, or where volume makes per-document pricing expensive. That last case arrives sooner than people expect once a monthly run is involved.
Reading a field off an invoice is close to solved and worth buying. Deciding what that field means inside your process is the part worth building.
What We Have Actually Built
Worth being specific, because expertise here is easy to claim and hard to check.
A Word add-in with Office.js, a DOCX editor working against OOXML directly, and a PDF processing tool. Those are our own projects rather than client work, which means we can show you the code and how the awkward parts were handled.
The awkward parts are the point: tracked changes, content controls, a table crossing a page break, and a file that is perfectly valid OOXML and still opens wrong.
What It Costs
A focused add-in is usually four to eight weeks. A batch pipeline depends almost entirely on how consistent the input documents are.
Work opens with a paid assessment of a real sample, which tells you whether word add-in development is the right shape for the problem before you commit. Send us five representative documents and you get that answer in writing.
Related Services
Where documents need data assembled from several systems first, that is data and BI. Where you want fields read out rather than written in, that overlaps with AI and LLM work, and where output is served at volume, that is infrastructure.