How to Grow Your Marketplace to 500k Users

PromptBase founder Ben Tossell grew the AI prompt marketplace from zero to 500,000 users and 300,000 listings by acting as the first seller, prioritizing seller acquisition over buyers, treating early sellers exceptionally well, leveraging sellers as an affiliate network, and optimizing listings for SEO. Tossell shared these strategies in a blog post detailing the marketplace's growth.

How to Grow Your Marketplace to 500,000 Users What I learned growing PromptBase from an empty marketplace into a business with 500,000 users and 300,000 listings. I grew PromptBase https://promptbase.com , a marketplace for AI prompts, from zero to more than 500,000 users. When I started, I had no users, two listings, and a website that did not look particularly great. This was before AI tools could help you design and build everything. You can read the post I wrote on the day I launched it https://daily.tinyprojects.dev/136 . I was still trying to work out whether anyone would want to sell an AI prompt, let alone buy one. Marketplaces are hard to get started, but they are fantastic businesses once they work. Every new seller adds more products. More products attract more buyers. More buyers attract more sellers. That loop is why marketplaces can become so difficult to stop. They're also incredibly fun to run. You're looking after a small economy filled with buyers, sellers, browsers, big spenders, and people trying to make their first sale. Here are the things that helped me get PromptBase moving. 1. Be seller number one If you can, become the first seller on your marketplace. I uploaded the first few prompts to PromptBase myself. It gave the site some initial inventory, and nobody cared that the owner was selling products on his own marketplace. More importantly, it forced me to use the seller experience. I saw where the listing form was confusing, which information was missing, and what it felt like to wait for a sale. It's much easier to build for sellers when you are one. 2. Get sellers before buyers People often describe marketplaces as a chicken and egg problem. At the very start, I don't think they are. You need sellers first. A marketplace without inventory is just an empty website. Sellers are also more motivated to take a chance on something new because they want to make money. Your job is to show them that your marketplace could be a good place to do it. Find the places where your sellers already spend time. For PromptBase, that was Reddit. I left relevant comments in AI communities explaining that, if someone wanted to do the very strange new thing of selling a prompt, they could do it on PromptBase. Don't spam every community you find. Join useful conversations and tell the right people about the site when it genuinely helps them. 3. Treat your early sellers like deities Once someone joins your marketplace, do everything you can to keep them interested. Tell them when a listing gets a view or a favourite. Send them a personal message after their first sale. Fix the bugs they find immediately. Build the small features that make their work easier. Share their listings from your own social accounts. At this stage, your early sellers are taking a risk on you. If they keep adding good products, the marketplace starts to feel alive. If they lose interest, you're back to an empty site. Their questions are also some of your best product research. If three sellers struggle with the same thing, it probably needs fixing. 4. Help sellers bring your first buyers Getting buyers is harder, especially when your marketplace is small and does not have much inventory. This is the point where many marketplaces stall. If sellers do not make sales, they eventually stop posting. The easiest place to find your first buyers is often through your sellers. A marketplace comes with a built-in affiliate network. Sellers want to make sales, so they have a reason to share their listings on social media, their own websites, and anywhere else they have an audience. Make that easy. Let sellers customise their storefront so they are proud to share it. Give them personal links and a reason to use them, such as lower fees on any sale they bring in. Both worked well for us on PromptBase. 5. Turn every listing into a landing page Marketplaces have an SEO advantage that most websites do not. Every new product creates a new page of user-generated content that can appear in Google. One very specific listing might only bring in one or two visitors each month. That does not sound exciting. But when you have hundreds or thousands of listings, those small numbers add up. The visitor who lands on one product may then browse the rest of the marketplace and buy something else. PromptBase now has around 300,000 listings. That is 300,000 pages, each with a chance of bringing someone new to the site. Make sure each listing has a useful title, description, category, and a clean URL. Then make related products easy to discover. SEO takes time, so start doing this while the marketplace is still small. 6. Add trust early A marketplace exists to make a transaction between two people easier. You could spend days phoning people in Italy to find a spare house for your holiday. Airbnb makes that transaction simple, then charges a fee for doing so. Your marketplace needs to remove the same kind of uncertainty for its buyers and sellers. Reviews are one of the easiest ways to do this. After a purchase, let the buyer rate the product and the seller. When the next buyer sees hundreds of positive reviews, their decision becomes much easier. Reviews compound over time, so add them early. I added them too late on PromptBase, and I wish I had not waited. 7. Add recurring revenue Most marketplaces make money by taking a percentage of each transaction. That can work very well, but the revenue is often choppy. A strong month can be followed by a quiet one. A seller subscription can make the business more predictable while giving your best sellers better tools. On PromptBase, our seller plan included lower marketplace fees, a trends dashboard showing what buyers were searching for, and the ability to promote listings. The subscription should help sellers make more money, not just lock basic features behind a paywall. If the value is clear, the plan becomes an easy decision for an active seller. 8. Keep the flywheel moving Running a marketplace is a constant balancing act between buyers and sellers. You will almost never have the perfect amount of both. Sometimes you will have plenty of sellers but not enough demand. Focus on distribution, sharing, and buyer trust. At other times, buyers will be searching for things you do not have. Recruit more sellers and show existing sellers what people want. Keep watching where the balance has shifted, then work on that side. Over time, each new listing, review, seller, and buyer makes the next one easier to get. Make payouts a reason sellers stay As PromptBase grew, seller payouts became one of the hardest and most expensive parts of running it. Stripe Connect charged us for active accounts and payouts, and some sellers could not use it at all because their country was unsupported. That is why I built Zoneless. It is an open-source alternative to Stripe Connect for marketplace payouts. It uses USDC, a digital dollar designed to stay worth one US dollar, and sends it to a seller's wallet in seconds. The API and seller onboarding follow are the same as Stripe Connect, so you do not need to redesign your marketplace or existing integration. You can self-host the whole stack, keep control of your payout system, avoid massive payout fees and improve your profit margins. You also do not have to replace Stripe everywhere. PromptBase still lets buyers pay normally while Zoneless handles seller payouts. If you want to do the same, read the guide to running Stripe and Zoneless side by side /blog/run-stripe-and-zoneless-side-by-side , or start with the marketplace quickstart /docs/marketplace-quickstart . Marketplaces are hard businesses to start, but they are worth it. Get the first sellers, help them make their first sales, and eventually you'll have an self-sustaining business with incredible value. Break free from Stripe Self-host Zoneless, or get started for free on Zoneless Cloud. No credit card required · Apache 2.0 licensed