PromptBase
PromptBase is the biggest name in the prompt marketplace. Prompts list for anywhere from a couple dollars to closer to ten, and the person who wrote it keeps most of the sale (their revenue split runs around 80%). What you're buying is text: a set of instructions someone else figured out for a similar task. You paste it into ChatGPT, Claude, Gemini, or whatever it was written for, swap in your own details, and see what comes back. It's genuinely useful if you're comfortable adapting someone else's wording to your own situation. What you don't get is any guarantee it performs the same for you as it did in the listing's screenshot.
FlowGPT
FlowGPT works similarly, prompts and custom GPTs shared in one place, with a community layer on top (upvotes, comments, trending lists). It's a good spot to browse what other people are building. But it's a single destination: no API, no way to plug a FlowGPT prompt into anything else you're already using. You visit the site, copy what you need, and leave.
OpenAI GPT Store
The GPT Store is built into ChatGPT itself, which makes it the easiest of the four to actually use, no copying and pasting required. The tradeoff is that everything on it only works inside ChatGPT. If your team uses Claude, or a mix of tools, a GPT Store listing isn't reachable. Discovery also leans heavily on popularity rather than curation, so finding something genuinely good for your specific task takes some digging.
Prompt Hub
Prompt Hub (prompthub.us) is a different kind of tool, worth separating from the three above. It's built for engineering teams already deploying prompts inside a product: version control, testing, an API to pull the latest prompt into their own code. If you're a developer managing prompts across a live product, it solves a real problem. If you're looking for a finished result you can hand to someone non-technical, it's not really built for that, and it isn't trying to be.
What's missing across all four
The pattern's the same across all of them: you find something, then you still have to do the work of making it run. Paste it in, adjust it, hope it holds up on your actual input.
For a team, that gap gets worse, not better. Someone finds a good prompt on PromptBase or FlowGPT, pastes it into their own doc or their own chat history, and it stays there. A teammate doing the same job next week has no idea it exists, so they go find their own. GPT Store's team plans and Prompt Hub's version control help engineers and ChatGPT admins organize what they've built, but neither gets a non-technical teammate to a finished result: someone still has to open the tool, run it, and know what they're looking at. None of these four hand a team a shared place to just run something and see the same output everyone else gets.
Skillyo starts where these leave off. Run a skill and the result is already there, not something you have to assemble yourself. Save that result instead of losing it in a chat window. Refine the skill itself as you learn what works, instead of starting over with a new prompt every time. Share it with your team so everyone's getting the same quality of output, from the same skill, instead of everyone rebuilding it on their own.
None of that is really what a prompt marketplace, a GPT store, or a prompt management tool is for. Their job ends once you've got the file or the prompt in hand. Skillyo's starts there.