Your own niche marketplace — many sellers, one platform, you take the commission_

You see an opportunity: sellers of a certain niche product/service (say: vintage accessories, local freelance services, regional crafts) don't yet have a dedicated place to meet buyers seriously looking for that category. Tokopedia/Shopee are too general, and big competitors haven't entered. A niche marketplace is a big opportunity — far beyond a single-brand online store, you become the gatekeeper of quality, take a commission from each transaction, and build a two-sided database (buyers + sellers) that's hard to duplicate. We build a multi-vendor marketplace: every seller has their own dashboard (manage products, view orders), buyers can purchase from many vendors in a single checkout, an escrow system that holds funds until the goods arrive, two-way ratings (buyer rates seller, seller rates buyer), and an admin dashboard for you to manage commissions and disputes. From IDR 15M, usually 8-16 weeks — a big investment but a big reward for the right opportunity.

A marketplace is one of the most complex types of custom software because it has to handle many roles at once with different interests. We use a modular architecture: the buyer layer, seller layer, admin layer, and payment layer are all separated but connected via an internal API. The database is designed with a tenant model — every vendor 'rides along' in the same database but their data is isolated via permissions. For performance, the most frequently accessed catalog pages are pre-rendered and served from a CDN, with smart invalidation when there's a new product/stock update. A dedicated search engine (Meilisearch or Algolia) handles queries with complex filters so the response is under 200ms. The escrow system is implemented with split payments: funds enter the escrow account, and 7-14 days after the buyer's confirmation the funds are released to the seller after the commission is deducted. Every movement of funds is recorded in a double-entry ledger for strict auditing. Dispute resolution is designed as a workflow state machine — every transition (complaint → mediated → resolved) requires a specific action from the relevant party. For anti-fraud, we set up signal monitoring: a new seller with a sudden high order volume, repeated IPs, suspicious refund patterns.