How to open a .skill file on a Mac

Why it opens in ChatGPT, or in Claude

We checked on a Mac with macOS 27.2 on 7 November 2026, with the Claude desktop app (2.19675.0) and the ChatGPT desktop app (26.1103.32239) installed:

• Claude declares .skill files as "Skill File", a kind of ZIP archive.
• ChatGPT declares the same extension as "ChatGPT Skill".
• macOS listed both apps for a .skill file made by Anthropic's packaging script, chose ChatGPT as the default, and Finder called the file a "ChatGPT Skill".

Which app wins on your Mac depends on what you have installed. We didn't test what each app does with the file once it opens. To choose:

1. Once: Control-click the file, choose Open With, and pick the app.
2. Every time: select the file, choose File > Get Info, open "Open with", pick the app and click Change All.

Unzip it without any app

In Terminal, any of these extracts a .skill file as it is, without renaming it. We ran all three on macOS 27.2 against a file packed the way skill-creator packs it:

unzip quote-check.skill -d skill-files
ditto -x -k quote-check.skill skill-files
tar -xf quote-check.skill -C skill-files

In Finder, rename it instead: turn on Finder > Settings > Advanced > Show all filename extensions, change .skill to .zip, confirm the new extension if Finder asks, and double-click the .zip. Apple says the unzipped folder appears beside it. Open SKILL.md in TextEdit.

Install it in Claude, or in Claude Code

• Claude (desktop app or claude.ai): Customize > Skills, then +, + Create skill, Upload a skill. Claude's help asks for a ZIP of the skill folder and doesn't mention .skill; if the picker won't take the .skill file, pick a copy renamed to .zip. Code execution must be on. More in how to install Claude skills.
• Claude Code: unzip quote-check.skill -d ~/.claude/skills/ puts it at ~/.claude/skills/quote-check/SKILL.md, because the file holds the skill's folder at its top. Claude Code picks it up in the running session; if ~/.claude/skills didn't exist before, type /reload-skills first, or start a new session. /skills lists it. More in how to install skills in Claude Code.

From someone else? Anthropic's docs say to use skills only from sources you trust and to read every file in one you didn't write, scripts included, before Claude runs it.

A worked example: the file that opened in the wrong app

Illustration: a made-up business. Jonas runs a small print shop. His designer made a skill in Claude that checks customer files before printing and sent him quote-check.skill. He double-clicked it and the ChatGPT app came up. He ran one line in Terminal to see what he'd been sent:

$ unzip -l quote-check.skill
  Length      Date    Time    Name
---------  ---------- -----   ----
      912  11-07-2026 09:12   quote-check/SKILL.md
     1430  11-07-2026 09:12   quote-check/references/paper-sizes.md
---------                     -------
     2342                     2 files

Two text files, no scripts. He made a copy named quote-check.zip and uploaded it in Claude under Customize > Skills, the way Claude's help describes, then set .skill files to open with Claude in Get Info so the next one from his designer lands there.

Next step: one copy for the whole shop

The designer will change the paper sizes again, and each file she sends is a new copy for each person. How to send a skill file to a coworker covers what email, Slack and Teams do with the file and the link that replaces it: in AI Skill Pod the skill sits in one pod, and each person reaches it from their own Claude, Cursor or ChatGPT (Pro, Business, Enterprise). Free covers up to 3 members and 10 skills.

Questions

Why did my .skill file open in ChatGPT?

Both the ChatGPT and Claude desktop apps for Mac declare .skill files as their own type. On our test Mac with both installed, macOS picked ChatGPT. Control-click the file, choose Open With and pick the app you want, or set it for every .skill file in Get Info with Change All.

How do I see what's inside a .skill file on a Mac?

Drop it in the free .skill file viewer, or run unzip my-skill.skill -d my-skill in Terminal. The file is a ZIP, so unzip, ditto -x -k and tar -xf all extract it without renaming it.

Can I just rename a .skill file to .zip on a Mac?

Yes: it's a ZIP inside. Turn on Show all filename extensions in Finder's settings to see the ending, rename it, confirm the new extension if Finder asks, and double-click the .zip.

Where do I put a .skill file for Claude Code on a Mac?

Unzip it into ~/.claude/skills/, so the skill sits at ~/.claude/skills/<skill-name>/SKILL.md. Claude Code picks it up in the running session (run /reload-skills first if the skills folder is new).