Popstack.

The problem

Independent makers who run multi-vendor pop-up stores manage the entire operation by hand, spread across WhatsApp, Instagram, email, and spreadsheets. The critical bottleneck is manual sales logging: every sale means reading a tag, writing on a notepad, and later transcribing to Excel — which works at low volume but breaks down entirely during busy periods, when queues form and items get missed.

Supplier coordination and terms collection are fragmented and manual, suppliers have zero real-time visibility into what's selling, and post-event reconciliation — calculating each supplier's payout from raw notes — is time-consuming and error-prone. No existing tool solves the full workflow end-to-end; Square plus spreadsheets is the dominant workaround, fragile above ~50 products.

The solution

Popstack is event operations software purpose-built for the maker pop-up format, framed around a single event lifecycle rather than a permanent shop. Organizers create an event by describing it in natural language, suppliers add products in whatever format they already have, sales are tracked live via QR codes, and payouts are calculated automatically at event close.

The MVP focuses on two architecturally coupled AI features: conversational event creation and AI-powered product upload. Both replace the manual intake workflow, and no AI output is ever saved without passing through a mandatory human review step. A per-supplier payout summary is the next high-priority feature in the build sequence.

How it works

Popstack runs on Claude Sonnet 4.6, selected for its instruction-following on multi-step conversation flows and reliable null-versus-invented-value behavior — critical for a tool handling money. For event creation, the AI extracts fields across a strict two-turn maximum, asking for commission rate and rent fee together if missing and generating JSON on "Review draft." For product upload, it silently parses free text or a spreadsheet (converted client-side by SheetJS) into a JSON array, excluding rows with no name or price and normalizing European decimal formats.

The stack is Lovable, Supabase Edge Functions, and the Anthropic API, with no RAG or fine-tuning — both features rely on prompt engineering alone. A hard rule runs throughout: never invent financial values. Automated evaluation reached 100% on both features after iteration, with zero invented financial values across all runs, and AI features can be disabled by removing the Edge Function without affecting core functionality.

Who it's for

Popstack is B2B2C. The primary buyer is the event organizer — an independent maker running 2–6 multi-vendor pop-ups a year, coordinating 3–12 suppliers, based in the Netherlands or UK, with no dedicated POS, accountant, or inventory manager. The secondary persona is the supplier, who gains real-time sales visibility and payout summaries.

The long-term growth model relies on converting suppliers — who experience the tool from the inside — into organizers, turning the supplier experience into the primary acquisition channel.

Why it matters

The settlement layer — inventory intake through QR-based selling to automatic payout — is an unmet need across existing POS and consignment tools, and pop-up retail is a growing format with tight-knit maker communities that drive word-of-mouth. Popstack sits at the intersection of three tailwinds: pop-up retail (9–12% CAGR), vertical SaaS (18–22%), and the European creator economy (22%).

The product is pre-launch (0-to-1) on a hybrid model — €15–25 per event for early adopters, converting to a €15–25/month subscription for organizers running 3+ events a year. It launches as a single-organiser, 10-supplier pilot at one real event in August 2026: lowest blast radius, fastest learning.

At a glance

Project

Popstack

Built by

Iulia Banciu

One-liner

Popstack is AI-powered event operations software for independent makers who run multi-vendor pop-up stores.