The short answer: you can't keep a Skill's instructions secret once a customer installs it, because the customer's AI has to read them, and so can the customer. If the method inside is what you're selling, sell access instead: keep the Skill on a server you control, let customers connect their AI app to it, check their access on every run, and send back only the result.
The rest of this guide explains why, compares the three ways to sell a Skill, and shows how the hosted option works.
Why an installed Skill can't stay private
A Claude Skill is a folder: a SKILL.md file with instructions, plus any scripts and reference files. Claude reads those files when the Skill is used. Anthropic's own advice to people installing a Skill is to read its files first, especially from a source they don't fully trust.
That's the right advice for buyers, and it's the problem for sellers. Anything a customer's AI can read on their account, the customer can open too. Even inside a company, Claude's skill sharing shares the Skill itself: colleagues can use it but not edit it.
You can make copying less convenient, for example by moving logic into scripts, but the customer still controls the environment the Skill runs in. Don't build a business on keeping an installed file secret.
Three ways to sell a Skill
1. Sell the files
Put the ZIP behind a checkout on Gumroad, Lemon Squeezy or your own site.
- Good: simple, and you can start today.
- Bad: the customer owns your instructions. Copies can spread, a refund doesn't take the files back, and every update means sending a new version and hoping people install it.
Fine for a cheap template. Risky when the method is the product. Selling a Claude Skill on Gumroad vs hosting it compares the two in detail.
2. Build your own app on the Claude API
Upload the Skill through Anthropic's Skills API, where custom Skills are private to your workspace, and build a web app around it.
- Good: the Skill never leaves your account, and you control everything.
- Bad: you're now building a SaaS: accounts, billing, a user interface, hosting and support. And customers have to leave the AI app they already use to come to yours.
3. Sell hosted access through a connector
Keep the Skill on a server and give customers a connector, so they use it from their own Claude, ChatGPT or Cursor:
Customer's AI app (Claude, ChatGPT, Cursor)
↓ connector (MCP)
Your server: is this customer allowed?
↓ yes
Your private Skill runs
↓
Only the result goes back to the customer- Good: customers stay in the app they already use, the instructions never leave your server, access can follow payments, and one update reaches everyone.
- Bad: someone has to build and run the server.
What hosted access needs
If you build it yourself, you'll need:
- A remote MCP server that Claude, ChatGPT and Cursor can connect to (see What is an MCP server?).
- Sign-in, so each run is tied to a customer.
- Access rules connected to payments: purchases, subscriptions, refunds and cancellations.
- A way to run the Skill: the model calls, plus any scripts and reference files it uses.
- Versioning, so you can publish an update and roll back a bad one.
- Usage tracking, so you know who uses it and how often.
- Connection instructions for each AI app, since each one adds a connector differently.
A developer can build this. Most people selling a Skill would rather not.
Or use expertrelay
expertrelay is this hosted option, ready-made:
- Upload your Skill ZIP: SKILL.md, references, scripts and assets.
- Review and test it privately: confirm what it does, what it needs, and what stays private.
- Sell access: create an offer, and customers connect once from Claude, ChatGPT or Cursor.
Access follows purchases, refunds, cancellations and memberships. When you publish a new version, every connected customer uses it on their next run. You see who claimed access and who uses it, and you keep 100% of your Skill revenue.
One honest limit: useful results can still reveal parts of how your method works. What stays private is the Skill itself, its instructions and files.
Sell your Skill without handing over the file →
FAQ
Can I sell a Claude Skill?
Yes. You can sell the files, build your own app around it, or sell hosted access. Only the last two keep the SKILL.md private.
Can customers see my SKILL.md if I sell the Skill?
If they install it, yes. Claude has to read the instructions to use them, and anyone with the files can open them.
Can I encrypt or hide a Claude Skill?
Not reliably. The customer controls the environment where an installed Skill runs, so anything Claude can read, they can find.
Can I sell my Skill in Claude's plugin marketplace?
Not as a paid listing. Anthropic's publishing docs don't describe any way to charge for a plugin; listed plugins are free to install. See The Claude plugin marketplace.
Does a hosted Skill work in ChatGPT too?
Yes, if it's delivered through a connector that ChatGPT supports. Skills also share an open format across apps; see Do Claude Skills work in ChatGPT and Codex?
What about Anthropic's Skills API?
It keeps custom Skills private to your workspace and is the right tool for building your own app. It doesn't, on its own, let customers use your Skill from their own Claude account.
