Case study: building Infus, an influencer marketplace on web, iPhone and Android
Infus is a marketplace where brands find creators and pay them safely. Brands post campaigns, creators pitch, and the money waits in escrow until the work is delivered. We built it for the USV ecosystem from an empty folder to a product that runs on the web, on iPhone and on Android, with a Shopify app on the side. Here is what that took.
The brief
The client wanted something more useful than a directory of influencers: a place where a small brand can post a job, compare proposals, pay once and know that the creator only gets the money when the post is live. Creators needed the opposite guarantee: that the money exists before they start.
What we shipped
- Campaigns, proposals and orders. An accepted proposal becomes an escrow order that is released on delivery, with reviews on both sides.
- Competitions with cash prizes, where many creators post and the brand picks winners.
- A social wall with follows, hashtags and video, so creators have a profile worth visiting between jobs.
- Realtime messaging with files, read receipts and online status.
- A creator score from 0 to 100, built from follower counts that refresh on their own across TikTok, Instagram, YouTube, X, Facebook and Threads.
- Withdrawals by bank transfer or in USDC and EURC stablecoins, each one approved by an admin before it leaves.
- A React web portal, native SwiftUI and Kotlin apps, a Shopify app for brands, and an admin back office. The web portal speaks English, Spanish, Romanian and Bulgarian, and the iPhone app 10 languages.
Decisions that mattered
One backend for every client. The web portal and both phone apps read and write the same collections, so a feature is designed once and then drawn three times, not rebuilt three times.
Money never moves from the phone. Early prototypes let the app write balances directly, which is fine for a demo and unacceptable for real money. In the shipped version one server function is the only thing allowed to change a wallet: escrow, releases, referral commissions and refunds all go through it, and every change is written to a ledger.
Payouts wait for a human. Automatic withdrawals are where marketplaces lose money to fraud. Every withdrawal is held for admin approval with a 24-hour promise; a rejected one is refunded to the creator's balance in the same step. Stablecoin withdrawals follow the same rule: nothing leaves before a person has looked at it.
Native apps, not a wrapped website. Chat, video and photo viewing feel like the phone they run on, and the apps keep pace with the web: competitions, files in chat and read receipts landed on all three at once.
What we would tell the next client
- Decide early who is allowed to move money, and make it one place on the server.
- Ship the core loop first (post, pitch, pay, deliver) and add the social layer after. People join for the money and stay for the profile.
- Plan the admin back office from day one. Approvals, reports and refunds are half of running a marketplace.
Infus is live at infus.app and on the App Store. If you are planning a marketplace or a platform with payments, the starting price and how a fixed quote works are on our Products page.