How to Create a Marketplace App: Steps & Cost (2026)
Create a marketplace app for iPhone: listings, search, buyer-seller chat and reviews in six steps with Borel, plus how payments and Apple's rules work.
By Sigsten Gustavii· · 9 min read
A marketplace has two kinds of people who both need a reason to show up. Sellers come when there are buyers, and buyers come when there is something to buy. That chicken-and-egg problem is harder than any code, which is why the building part should be as quick as possible.
This guide walks through how to create a marketplace app for iPhone with Borel, an AI app builder that writes native Swift. It covers what a marketplace needs, the six steps, the payment question every marketplace runs into, Apple's rules and the costs.
What a marketplace app needs
| Part | What people do | What Borel builds |
|---|---|---|
| Listings | Sellers post an item or service with photos, a price and a place | A listings table anyone can read and only the seller can change, with photos in file storage |
| Browsing and search | Buyers scroll, filter by category and price, and search | Lists, filters and a search field over titles and descriptions |
| Map | See what is for sale nearby | Apple Maps with a pin per listing |
| Messages | A buyer asks a seller a question | Conversations only their two members can read |
| Saved items | Keep a list of favourites | Saves that only their owner can see |
| Reviews | Rate a seller after a deal | Reviews tied to a seller's profile |
| Safety | Report a listing, block a person | Report and block on listings, messages and profiles |
All of that lives in Borel Cloud: a Postgres database, email sign-in and file storage that Borel runs, with nothing for you to set up. Borel writes an access rule for each table, so a listing can be browsed without an account while messages stay between two people.
How to create a marketplace app in 6 steps
Step 1: Pick a niche and a place
General marketplaces are owned by giants. Small ones win by being specific: used climbing gear, children's clothes in one city, handmade ceramics, tutors at one university. A narrow niche means a buyer finds something relevant on the opening screen, which is what makes them come back. Decide whether it is goods, services or rentals, and where you'll start.
Step 2: Describe the marketplace to Borel
Open Borel and describe it the way you'd explain it to a friend: who sells, who buys, what a listing holds and how people get in touch.
Make a marketplace app for used outdoor gear in Stockholm. Anyone can browse listings without an account. Sellers sign up with email and post an item with up to six photos, a title, price in SEK, condition, category and the area of town. Buyers can search, filter by category and price, see listings on a map, save favourites, and message the seller. After a deal, the buyer can leave a star rating on the seller's profile. Every listing and message can be reported, and people can block each other. Sellers mark an item as sold.Borel's planner, Penny, reads it and asks about anything unclear. Then the app is written in Swift with SwiftUI and compiled with Xcode on Borel's Mac. You don't need a Mac yourself.
Step 3: Let Borel build listings, search and messages
Within a minute or two, the marketplace opens on a live iPhone in your browser. Check the parts that make or break it:
- Post a listing with photos from one test account, and find it from a second through search and the map.
- Message the seller from the buyer's account and reply from the seller's.
- Change a listing from the seller's account, and confirm the buyer's account can't.
- Mark it sold and see it leave the list.
The map uses Apple Maps, so there is no map key to get. Photos come from Apple's own photo picker, which needs no permission prompt, or straight from the camera on a real phone.
Step 4: Decide how money moves
This is the step most marketplace guides skip. Apple's Guideline 3.1.3(e) says that when people buy physical goods or services used outside the app, you must use a payment method other than in-app purchase, such as taking a card directly. So there are three honest options:
- Pay in person. Buyers and sellers agree a price in the chat and settle it themselves, the way classifieds apps work. Nothing to build, and the right place to start.
- Card checkout through Stripe. Add your own Stripe key under Tools, in Keys, and Borel calls Stripe from its server, so the key is never inside the app. A checkout page the app opens is within reach; expect to test it carefully.
- Paying sellers out. Holding money, taking a commission and paying sellers needs Stripe Connect and identity checks for every seller. That is a project of its own, not one message.
If you sell something digital inside the app instead, like a featured listing or a seller subscription, that does go through Apple's in-app purchase. Borel builds those with StoreKit when you use the Add payment button.
Step 5: Add trust and safety
Listings and messages are user-generated content, so Apple's Guideline 1.2 applies: a way to filter, report and block, and contact details. Borel's moderation kit puts Report and Block on every listing, message and profile, hides what someone reported at once, checks text before it is posted and lists blocked people in settings. Reviews help too: a seller with ten good ratings sells faster. Write your marketplace rules, such as what may not be sold, in plain words in the app.
Step 6: Test with real sellers, then publish
Fill the marketplace before you open it. Invite ten sellers from your niche to post their items while you test. With Pro, Borel Companion installs the app on your iPhone from a PC or a Mac, so you can photograph real items. When the shelves are stocked, Stamp checks the app against the rules Apple most often turns apps down for, and Publish builds, signs and uploads it under your own Apple Developer account. Give the reviewer a demo account with a listing and a conversation already in it.
App Store rules for marketplace apps
| Guideline | What Apple asks | What it means for you |
|---|---|---|
| 3.1.3(e) Goods and services outside the app | Use payment methods other than in-app purchase | Settle in person, or take cards through a processor like Stripe |
| 3.1.1 In-app purchase | Digital features unlocked in the app use in-app purchase | Featured listings or seller plans go through Apple |
| 1.2 User-generated content | Filter, report, block and contact details | Borel's moderation kit, plus your contact email |
| 5.1.1(v) Account deletion | Delete account in the app | Built into every Borel app with accounts |
| 2.1 Completeness | Demo account details for apps with a login | Give the reviewer a seller account with listings |
Sellers also need to follow the law on what they sell. Ban regulated goods in your rules and act on reports quickly.
How much does it cost to make a marketplace app?
| Item | Cost | Notes |
|---|---|---|
| Borel Free | $0 | 5 credits a day; build and try it in your browser |
| Borel Pro | From $20 a month | Install on your iPhone and publish to the App Store |
| Apple Developer Program | $99 a year | Paid to Apple |
| Running the app | Pay as you go | Database and photo storage from a balance you top up |
| Card payments | The processor's fees | Only if you take payments in the app |
| An agency | Most projects $10,000 to $49,999 (Clutch, 2026) | Two-sided apps with payments tend to cost more |
With Borel's lowest Pro tier paid monthly and Apple's membership, a marketplace costs $339 a year to build and publish, plus the cloud your listings use. See pricing.
How marketplace apps make money
- Commission on each sale, which needs card payments and payouts, so it usually comes later.
- Featured listings, a digital extra sold with Apple's in-app purchase.
- A seller subscription for shops that list a lot, also through in-app purchase.
- Local ads from shops in your niche, shown as ordinary listings you mark as sponsored.
How to choose the right marketplace app builder
- Borel, for an iPhone marketplace with native photos, maps and chat, built from a description and published from your browser.
- [CatDoes](/compare/catdoes), if Android sellers matter from the start; it builds React Native apps for both stores.
- [FlutterFlow](/compare/flutterflow), if a developer will hand-tune the app in a visual editor.
- A marketplace platform on the web, if a website is enough and most buyers arrive from search.
- An agency, if you need escrow, payouts and seller verification from the opening day.
Marketplace builders compared
| Builder | What it makes | Backend | App Store from |
|---|---|---|---|
| Borel | Native SwiftUI for iPhone and iPad | Built in: database, sign-in, storage | $20 a month |
| CatDoes | React Native for iPhone and Android | Its own cloud | $42 a month |
| FlutterFlow | Flutter for iPhone and Android | You connect one | $39 a month |
| Xcode by hand | Native Swift | You build or rent one | Free tools and a Mac |
Prices are each company's lowest plan that publishes to the App Store, from their pricing pages in October 2026.
The Bottom Line
The code of a marketplace (listings, search, maps, messages, reviews and safety) is now a description away. Borel builds it natively and keeps each person's data behind the right rule. Start with in-person payment and one niche, fill the shelves with real sellers, and add card checkout when there are deals worth taking a cut of. Describe yours on Borel and try it free on a live iPhone.
Questions people ask
Can I build a marketplace app without coding?
Yes. Borel builds listings, search, maps, buyer-seller messages, reviews and moderation from a plain description, with a database it runs for you. Card payments and seller payouts are the part that needs the most extra care.
Can a marketplace app use Apple's in-app purchase?
Not for physical goods or services used outside the app. Guideline 3.1.3(e) asks for other methods, like taking a card directly. Digital extras inside the app, such as featured listings, do use in-app purchase.
How much does it cost to make a marketplace app?
With Borel, from $20 a month for Pro plus Apple's $99 a year, and the cloud your app uses. Clutch's 2026 data puts most agency app projects at $10,000 to $49,999.
How do I get the opening sellers and buyers?
Start narrow: one niche in one city. Invite sellers personally and help them post, so the app is full before buyers arrive. Then go where buyers already gather, like a club, a forum or a Facebook group.
Can buyers and sellers chat in the app?
Yes. Borel builds conversations that only their two members can read, with report and block on every message. New messages show when the app is opened or refreshed, since Borel apps don't send push notifications yet.
Does a marketplace app need a backend?
Yes, for accounts, listings, photos and messages. Borel gives every app that needs one its own backend, Borel Cloud, with no setup or keys.
I started Borel because I wanted to make iPhone apps without a Mac or a team behind me. If this helped you build something, I would love to see it.
– Sigsten
Make your iPhone app in Borel
Describe the app you want and see its first screens before you pay anything.
See your app free