Copilot vs Onyx vs Glean: the open-source case for owning permissions

Who decides what the assistant does with what it finds

Every buyer comparing Microsoft 365 Copilot, Onyx and Glean starts with the same list. Connect the tools, find the page that answers the question. That list covers the first half of the problem. The second half starts a second later, when the assistant holds the page and someone has to settle what it may do with it.

All three answer the first half, in three different ways, and each vendor's own page says how. Copilot reads what Microsoft 365 already holds, Onyx indexes 40+ apps, Glean connects 275+. The second half is where the architectures separate, because whoever holds the permission model decides which documents the assistant can see and which actions it can take on them.

Copilot hands the decision to the tenant

Microsoft sells Microsoft 365 Copilot as an add-on at $30 a user a month billed yearly, or $31.50 billed monthly (Microsoft, checked October 2026). It sits on top of a separate qualifying Microsoft 365 plan. The work it reads arrives through Microsoft Graph: mail, files, chats, meetings, and 100+ connectors for line-of-business systems. It shows up inside Word, Excel, PowerPoint, Outlook, Teams, Loop, Edge for Business, OneDrive and SharePoint.

The controls that set its reach belong to Microsoft. SharePoint Advanced Management governs oversharing, admin settings govern agents, and Copilot Analytics measures use. A buyer inherits a permission model along with the tenant, which suits a company already governed inside Microsoft 365. It leaves little room to change the model, and none of it is code your team can read.

Onyx indexes the estate and inherits what each source allows

Onyx lists Business at $20 per user a month on annual billing and quotes Enterprise separately (Onyx pricing, checked October 2026). That page puts 40+ app connectors on the Business plan. Onyx's own Copilot comparison advertises open source, self-hosting and actions through MCP and OpenAPI (Onyx, checked October 2026). The code is public in the Onyx repository.

Permissions are handled at index time. Onyx inherits each source system's permissions, so a document a person cannot open in Drive stays out of the answer that person gets. That is a real safeguard, and a fair answer to the oversharing worry Onyx raises about Copilot's inheritance of SharePoint permissions.

What Onyx leaves in its own admin surface is the rulebook. Connector setup, index scope and which actions the assistant may take sit in Onyx's configuration, on Onyx Cloud or on a server you run, apart from the code that defines the assistant's work.

Glean sells the widest reach as a managed platform

Glean describes itself as an enterprise AI platform: an assistant, enterprise search and agents. Its pages put 275+ connectors and 40+ models behind permission-aware answers, under a governance layer it calls Glean Protect (Glean, checked October 2026). Pricing is not published, and the site routes buyers to a sales conversation. Deployment is a service Glean runs for you.

For a company with a decade of documents spread across a dozen systems, Glean is often the better pick, and Onyx is close behind it. Both were built to find one answer inside a large estate, and both do that job with a retrieval quality that a repository of agent definitions does not touch.

The second half, written as a file your team owns

A Kortix project is a git repository, and kortix.yaml declares the agents in it. Open source. Read it, fork it, audit it. Each agent names its markdown definition and carries grants for connectors, secrets, permissions and skills. A grant left out resolves to none, so a new agent starts with nothing it was not given. The manifest excerpt shows the starter's default agent holding every grant. A second agent holds permissions and no connectors at all, because it reads untrusted transcripts and has nothing to send anywhere.

That arrangement answers the second half of the question in a form a reviewer can diff. Per-resource permissions for people and agents. Roles, groups, and an audit trail. An edit to either appears in the same review as a code change. Sessions run on their own isolated machine, so the work an agent does with what it found happens somewhere you can inspect afterwards, not inside a vendor's tenant.

You also choose where it runs. Run it on Kortix Cloud, in your VPC, or on your own on-prem network. Self-host is free. Members then cost nothing on top of the credit pool. A team does not pay per head for the assistant and again for the work it delegates (see Kortix pricing).

Where each one fits

Copilot fits a company already standardised on Microsoft 365 that wants help inside Word, Excel and Teams, and is content for the tenant to govern the assistant. Onyx fits a team that wants an open-source, self-hostable search brain across 40+ tools and will tune the index itself. Glean fits a large estate where buying a managed knowledge layer beats building one.

Kortix fits the buyer who starts somewhere else: who may tell the assistant what to do, and where that answer lives. The answer lands in a repository, next to the agents it governs. If the work happens in Copilot Studio agents today, the Copilot Studio alternatives page covers that comparison; for the head-to-head with Microsoft's assistant, see Kortix vs Copilot.