AI assistants and search decision
Microsoft 365 Copilot Business
A narrow Copilot-like assistant (document search + chat + draft generation) is feasible for a single developer in about a week using existing LLM APIs, but reproducing Microsoft 365 Copilot's deep app integrations, enterprise features, and managed service experience is not realistic.
Visit website↗Open-source builds that already do this
Every project below is open source and already does this job today. Fork one, self-host it, or take the parts you need — the build prompt further down assumes an empty file, and this is the shortcut past that. Licences differ; check the one on each card before you ship.
What a replacement has to do
- A chat-style assistant that answers user questions using company documents and composes drafts (e.g., email or doc snippets) from LLM outputs with retrieved context.
What it still won’t have
- Deep native integration with Microsoft 365 apps (Word, Outlook, Teams) and real-time context
- Microsoft enterprise support, SLAs, and managed compliance
- Proprietary model tuning and any closed-source enhancements Microsoft provides
- Built-in org-level deployment, licensing, and billing handled by Microsoft
What remains hard
- Product polish and ongoing maintenance
First-year cost
Keep paying
Paying is—cheaper in year one.
On cash alone, building overtakes the subscription at 10 seats.
Money you would actually spend
Time you would spend
—
What you would spend
What we assumed
The verdict above measures whether you could build it. This one is only about money.
Runnable build prompt
Build a minimal business AI copilot as a web app using: Node.js + Express backend, React frontend, PostgreSQL for user/workspace metadata, an object store (S3-compatible) for documents, and a vector DB (weaviate or pgvector). Core features in scope: document ingestion (PDF/DOCX/email), embedding pipeline and similarity search, LLM orchestration with prompt templates, a chat UI showing source snippets and attribution, and basic auth + single-tenant workspace isolation. Out of scope: deep integrations with Microsoft 365 apps, custom model training, enterprise compliance certifications, and multi-region deployment. Include error handling for failed ingestion and API calls, unit tests for ingestion/search/LLM orchestration, and deployment instructions (Docker + cloud instructions).
How we checked
How the score was reached
- Partly verdict base52
- An open-source build was found+5
- 3 cited sources+3
- Evidence score60
The base comes from the verdict. Everything under it is a check that either happened or did not, and each one is a fact frozen in this record rather than a judgement made at render time — so the same evidence always produces the same number.
How scoring works →Cited sources · 3
Every page the run actually retrieved.
- official productMicrosoft Copilot (official product page)
- open sourcearc53/DocsGPT
- open sourceaingdesk/AingDesk
Integrity checks
What held up, and what did not.
