Microsoft Copilot and ChatGPT are both closed, hosted assistants, so the choice between them comes down to where each runs, what each can reach, and how each is bought. This page compares them from the vendors' own pages, then names the open-source Kortix option the either-or hides.
Microsoft Copilot is Microsoft's assistant inside its productivity apps and on the web. Microsoft says Copilot is integrated into Word, Excel, PowerPoint, Outlook and Teams, and that you can work with it across desktop, mobile and web (Microsoft 365 Copilot). The same product ships in tiers: Copilot Chat (Basic) is included with eligible Microsoft 365 plans, while Microsoft 365 Copilot (Basic) and (Premium) add Copilot inside the apps and, on the paid add-on, work-data grounding through Microsoft Graph and Work IQ (Microsoft's Copilot overview).
ChatGPT is OpenAI's assistant, available on web, iOS and Android, and now organized around three jobs: Chat for everyday questions, Work for finished deliverables such as docs, decks and spreadsheets, and Codex for coding (ChatGPT overview). OpenAI sells it as per-seat plans, from a free tier to Business and Enterprise (ChatGPT pricing).
Both are closed and both are hosted. That is the shared fact a buyer should hold onto: neither Copilot nor ChatGPT can be self-hosted, and in both the answer comes from the vendor's cloud. Our Microsoft Copilot primer covers Copilot on its own.
The clearest difference is reach. Microsoft Copilot lives inside Microsoft 365, so it works where those documents and messages already are, and the paid tier grounds answers in Microsoft Graph and Work IQ. ChatGPT reaches its own surface: it connects to apps such as Gmail and Slack, and ChatGPT Work can create and edit docs, slide decks, spreadsheets, PDFs and images (ChatGPT overview).
Where each one runs is not a difference at all: Microsoft Copilot runs in Microsoft's cloud and ChatGPT runs in OpenAI's cloud. How you buy them does differ. Copilot is an add-on to an eligible Microsoft 365 plan, with Copilot Chat included at no extra cost (Microsoft Copilot pricing); ChatGPT is priced per seat, from $8 a month for Go and $20 for Plus to $25 per user per month for a Business standard seat, checked October 2026 (ChatGPT pricing).
Work content is the part a security review stops on. Microsoft applies Enterprise Data Protection when you sign in with a work account and states that prompts and responses are not used to train foundation models. OpenAI draws the line by plan: on the individual plans content is used to train its models unless you opt out, while ChatGPT Business and Enterprise workspaces are not trained on (ChatGPT pricing, ChatGPT Business).
Kortix is the open-source pick for a team that wants to own the system; Copilot and ChatGPT are the two closed assistants.
project (git repo + kortix.yaml)└─ session ──> cloud computer: an isolated sandbox on a branch named after the session└─ the OpenCode agent works└─ change request ──> you review & merge ──> mainThe project-to-merge loop, from the Kortix README on GitHub.
Compare Copilot with ChatGPT and you are choosing which vendor's assistant answers your prompts. You are not choosing who owns the system the work runs on, because in both cases that answer is the vendor. The open-source AI Operating System is what Kortix is: your agents, skills, company memory and connectors in one git repo you own, working on real cloud computers. The system is the thing you keep, and session work reaches main through a change request a person approves.
That is a different unit of work from "which assistant", and it is the option the Copilot-versus-ChatGPT framing leaves out. The head-to-head on the Microsoft side is Kortix vs Copilot; the wider field is in the alternatives guide; and the shortest version of each buyer question is in the FAQ.
Both ship coding help: Copilot works in Microsoft's developer tools, and ChatGPT includes Codex. If the job is an agent that runs on its own cloud computer and hands back a change request, that is a different tool, and it is what Kortix does.
No. Both run in the vendor's cloud. Kortix is the open-source option here: run it on Kortix Cloud, in your VPC, or on your own on-prem network, and self-host is free.
With Copilot or ChatGPT, the configuration lives in the vendor's product. With Kortix, agents, skills, company memory and connectors are files in a git repo you own, and session work reaches main through a change request.
Start with one job and grow from there.