You already wrote it. The SKILL.md you reach for every day is, unchanged, something other people will pay for. Selling it is not a second project — it is publishing the file you already have.
§ 01 A skill is one file
A skill is a SKILL.md — a reference document a model loads when it needs it. It follows the open agentskills.io specification, so the same file works in Claude Code, Codex CLI, OpenCode, claude.ai and the Claude API.
Nothing runs on your machine and nobody needs your API keys. That is what makes a skill the lowest-friction thing to sell: the other building blocks ask you to build something, while a skill asks you to write down what you already know.
§ 02 Use it yourself first
A skill nobody uses is a guess about what buyers want. A skill you use is evidence.
Install your own from Plugins and live with it for a week. You will find the missing edge case, the instruction that reads clearly to you and to nobody else, and the example that does more explaining than three paragraphs. That week is the difference between a listing that gets refunded and one that gets reviewed well.
§ 03 What buyers actually pay for
| Sells | Doesn't |
|---|---|
| A narrow job done properly | "Everything you need for marketing" |
| A worked example showing real output | A description of what the skill would do |
| Edge cases you already hit, written down | Generic advice the model already knows |
| Your judgement about what not to do | A list of tips scraped from a blog post |
The test is simple: could the buyer have got this from the model by asking nicely? If yes, it is not a listing yet. What you are selling is the hundred small decisions you made while the thing was failing.
§ 04 Publish it — two doors, same room
From the browser, the publish wizard walks the whole listing. From your editor, the Sigrix MCP server drafts, checks and submits it without you leaving Claude Code.
Either way a moderator reads it before it goes live. That review is the reason a Sigrix listing is worth more than a gist link.
§ 05 Free is a strategy, not a failure
A skill priced at $0 joins the public sigrix-free feed, which anyone can add with no account and no token. Your name and a link to your listing ride along inside the file.
That is the cheapest distribution you will find for a first listing: people install it, see how you think, and go looking for what else you have published. Charge for the second one.
§ 06 Updates reach buyers on their own
When you republish, the new version flows down the same feed every buyer already added — they run one update command, or none at all if they turned auto-update on. You are not emailing files to anyone.
That changes what is worth maintaining. A skill you keep sharpening compounds: the same listing gets better, the same buyers keep it installed, and the reviews accumulate on one page instead of scattering across versions.
Start with the one you opened today
Not the ambitious one you have been meaning to write — the scrappy file you already keep re-opening. Read how to price it, then put it on the skills marketplace.
One practical essay, every other Tuesday.
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