Atlas / Skills / Build your own

Build your own AI skills

AI Market Atlas · by Pro Pluribus

Skills and plugins for build your own that work in Claude, ChatGPT, Copilot or Gemini, checked 10 Nov 2026. Each passed the shelf's vetting test; read the note on each one.

Read before installing. Check who publishes a skill, what accounts it can reach, and whether it runs commands on your computer. Even official skills can.

Before you install7 checks

Build your own

Custom skills in Claude

Anthropic · AI vendor

Upload or write SKILL.md skills; Team and Enterprise admins can share them across the organisation.

Runs on: Claude on Free, Pro, Max, Team, Enterprise (code execution on)
Check: Your own content; Enterprise malware scanning on by default since 2 Oct 2026
Notable: Anthropic created the SKILL.md format and published it as an open standard (Dec 2025)

support.claude.com ↗support.claude.com ↗

Build your own

Skills and plugins in ChatGPT (custom GPT migration)

OpenAI · AI vendor

Build skills and private plugins (Plugin Creator); custom GPT instructions migrate into a skill inside a plugin.

Runs on: ChatGPT Business, Enterprise, Healthcare, Edu (skills); Plugin Directory in ChatGPT and Codex
Check: Admins manage plugins (bulk management from 15 Oct 2026); custom actions do not migrate and must be rebuilt
Notable: Custom GPTs retire 11 Dec 2026; migrated plugins start private

help.openai.com ↗help.openai.com ↗releases.sh ↗

Build your own

Gemini Skills and Workspace skill builder

Google · AI vendor

Write skills in the Gemini app or build them in a Google Doc with teammates; manage them in Workspace Studio; import SKILL.md files.

Runs on: Gemini app (all personal accounts 18+), Workspace Business and Enterprise editions
Check: Workspace admins can switch skills on or off (no admin controls in the consumer app); skills do not sync between app and Workspace
Notable: Replaces Gems: migration starts 17 Nov 2026; Gems end for Workspace business no sooner than 1 Mar 2027

workspaceupdates.googleblog.com ↗workspace.google.com ↗androidauthority.com ↗

Build your own

Copilot Cowork skill builder and plugin upload

Microsoft · AI vendor

Guided conversation to create a skill; upload .md, .zip or .skill files; upload a Claude-format plugin package, which Cowork converts; share with named colleagues.

Runs on: Microsoft 365 Copilot Cowork
Check: Admin governance and usage-based billing apply
Notable: Shipped with Cowork GA (Jun 2026). Microsoft accepts Claude plugin packages, which shows the format is now portable across vendors

learn.microsoft.com ↗

Build your own

Notion Skills

Notion · Software company

Teams write shared skills in Notion and export them as SKILL.md to Claude, Codex, Gemini and others, with update badges.

Runs on: Notion Agent; exported to other agents
Check: Your own content, so lowest supply-chain risk; plan gating not stated
Notable: Notion 3.7, 15 Sep 2026

notion.com ↗

Before you install any skill

Who publishes it? Prefer the AI vendor or the company that owns the app being connected.
Has it been reviewed? Look for a verified badge, or the security ratings on its skills.sh page.
What accounts does it connect to, and what can it do there? Prefer read-only; check anything that can send, pay or delete.
Does it run commands on your computer? A “Warn” rating often means it does, even for official skills.
Has your IT team approved it? Use the admin-managed catalogue where there is one.
Do you know how to disconnect it and revoke its access?
Finance, legal and HR output still needs review by a qualified person.

This map is a by-product of the work. Keeping track of what each of these actually does, and which ones are worth your time, is part of how I advise founder-led companies on AI. If you want that applied to your business, the first conversation is free.

Book a 30-minute conversation →

Compiled from public sources by Pro Pluribus; updated 10 Nov 2026. General information, not advice. Company names and logos belong to their owners and are used to identify them, without affiliation or endorsement. Terms