Social Marketplace Android & Web

I’m building an engagement-driven marketplace that feels as easy and addictive as scrolling through Twitter, yet fully focused on buying and selling. The core of the product is a real-time social feed where every post represents an item for sale. Users will be able to list handmade goods, digital products, and second-hand items—essentially anything they wish to move—then have those listings surface in a chronological feed that other users can like, comment on, repost, or purchase from directly.

I need a full Android app and a responsive web experience that stay visually in sync and share one backend. Speed and fluidity matter; the feed should refresh instantly, images should lazy-load smoothly, and notifications should land in real time. Think infinite scroll, hashtag or keyword search, user mentions, and a friction-free listing workflow (photo upload, price, short caption, post).

Key functionality I expect:
• Unified auth (email or social login)
• Seller profile pages with follower counts and ratings
• Secure checkout that can handle both physical and digital fulfillment paths
• Moderation tools for reporting or hiding inappropriate items
• Scalable database and media storage—Firebase, Supabase, AWS, or a stack you’re confident runs lean under load

Deliverables:
1. Production-ready Android APK and deployable web build
2. Source code with clear README and environment setup
3. API / database schema documentation
4. Short demo video or live staging link showcasing listing, feed interaction, and purchase flow

Acceptance criteria will be the ability to create an account, post an item, have it appear instantly in another user’s feed, and complete a checkout end-to-end.

If you’ve shipped chat-like feeds or marketplace apps before, let’s talk about your preferred stack and timeline so we can lock milestones and move fast. You must state your preferred stack in the bid.