Claude Skills vs Custom GPTs: What's the Difference and Which Should You Use?

Claude Skills are portable instruction folders that load automatically when your request matches them, while Custom GPTs are standalone assistants you open by hand inside ChatGPT. Pick a Skill for repeatable work you do inside Claude; pick a Custom GPT for a simple assistant you want to share with other ChatGPT users.

They solve the same basic problem — teaching an AI your way of doing something, once, so you don't re-explain it every time. But they are built very differently, and that difference decides which one fits your work.

What a Claude Skill is

A Skill is a folder. At its center is a file called SKILL.md: plain text instructions in Markdown, with a short header (a name and a description) at the top. The folder can also hold scripts, reference documents, and templates that the instructions point to.

Three things matter about how Skills work:

• They load on their own. Claude reads the description in the header and pulls the Skill in only when your request matches it. You don't open anything or switch modes. If nothing matches, the Skill stays out of the way.
• They are portable. Skills follow the open Agent Skills standard, so the same folder works in Claude.ai, in Claude Code, and through the API. You install one by uploading the ZIP in Claude's Customize → Skills panel, or by dropping the folder into your skills directory. Anthropic's own examples live in the anthropics/skills repository on GitHub.
• They can do more than talk. Because a Skill can include scripts and reference files, it can run real steps — process a spreadsheet, fill a template, follow a checklist with your exact rules — not just reply in a certain style.

The official overview is in Anthropic's Skills documentation.

What a Custom GPT is

A Custom GPT is an assistant you configure inside ChatGPT. You give it instructions, upload some knowledge files, and pick which built-in tools it can use (web browsing, image generation, code running). Then it lives as its own chat: you open it when you want it.

Key traits:

• You go to it. A Custom GPT doesn't watch your normal chats and step in. You start a conversation with that specific GPT, every time.
• It's hosted by OpenAI. The GPT only works inside ChatGPT. There's no file you can take elsewhere — if you move to another tool, you start over.
• Sharing is easy. You can send anyone a link, or publish it in the GPT Store. For reaching non-technical users who already use ChatGPT, this is the smoothest path there is. OpenAI explains the setup in its GPTs help page.

The core difference in one paragraph

A Skill is a set of instructions your assistant carries with it and applies when relevant — closer to a procedure in a handbook. A Custom GPT is a separate assistant with a fixed personality and setup — closer to hiring a specialist you visit. Skills travel with you across Claude products and can include working files; Custom GPTs stay in ChatGPT but are easier to hand to other people.

Which should you use?

Choose a Skill if:

• The task repeats — a weekly report, a document format, a review process — and you want it handled the same way every time.
• The job involves your files, templates, or a script. Skills carry reference material and can execute steps, not just describe them.
• You work across Claude.ai, Claude Code, or the API and want one setup to follow you.
• You want the help to appear automatically in a normal conversation, without opening a special assistant first.

Choose a Custom GPT if:

• You want a simple chat assistant — a writing coach, a brainstorming partner, a Q&A bot over a set of documents.
• Your audience is other people. Sending a GPT Store link to a colleague or customer is easier than asking them to install files.
• Everyone involved already uses ChatGPT and nobody needs the setup to work anywhere else.

You can also combine them. Plenty of people keep a Custom GPT as the friendly front door for a team, and use Skills for their own heavier, file-based workflows. The two aren't rivals so much as different shapes of the same idea: instructions written once, reused many times.

If you're browsing ready-made Skills to see what the format can do, the AI Services Market directory lists skill packs you can open and read before installing — a quick way to learn what a good SKILL.md looks like.

The bottom line

If the work is yours, repeats, and involves files or fixed procedures, use a Skill. If you need a simple assistant to share with people on ChatGPT, use a Custom GPT. And if you're not sure, start with the question: "Do I want help that follows me, or a place I go?" The answer picks the tool.