AI agents in your process
Agents that watch listings, prices, inventory, ads, and supply chain — and act on rules you define. Plugged into the tools you already use.
Custom software for Amazon sellers — a CRM that works with AI agents
SellerUp builds custom software for marketplace sellers: internal dashboards, server-side platforms, integrations with marketplaces and suppliers. One source of truth instead of seven scattered spreadsheets.
What we build
Workflow automation. AI agents. Custom CRM.
End-to-end engineering for marketplace sellers — built around your data, your operations, your goals. Not a SaaS subscription. A system that becomes part of your team.
Workflow automation
We map your operations, find the repetitive bottlenecks, and ship pipelines that run on their own — keeping your team focused on strategy.
Custom software
Internal dashboards, server-side platforms, integrations with marketplaces and suppliers. Built specifically for how your business actually works.
What we build for marketplace sellers
Internal systems
Platforms unifying stock, orders, suppliers, and resource planning in one place.
Integrations
Connectors for Amazon, Allegro, Kaufland, and other platforms, plus ERP, spreadsheets, and delivery services.
Dashboards
Operational and financial dashboards: sales, margin, ads, stock — in real time.
Server-side pipelines
Scheduled data collection and processing: marketplace reports, competitor prices, delivery statuses.
FAQ: custom software for marketplace sellers
Why not an off-the-shelf SaaS?
Because ready-made tools cover roughly 70% of the task, and the remaining 30% is exactly what makes your business different. We build for that 30% and integrate the off-the-shelf part wherever it already works. If a subscription genuinely covers your process end to end, we will tell you to buy it — the side-by-side comparison on the services page sets out when each option wins.
Who maintains the system after launch?
Whichever you prefer, agreed before we start. Either we stay on support and keep the integrations current as marketplace APIs change, or we hand the system over to your team with documentation and training until they run it confidently without us. There is no arrangement where you are locked in because only we understand the code.
What do you actually build?
Four kinds of thing, usually in combination. Internal platforms that unify stock, orders, suppliers and resource planning in one database. Connectors to Amazon, Allegro, Kaufland and other platforms, plus ERP, spreadsheets and delivery services. Operational and financial dashboards. And server-side pipelines that collect marketplace reports, competitor prices and delivery statuses on a schedule.
Who owns the code and the data?
You do, without qualification. The system is built as your property: the code, the database and the pipelines run on your infrastructure, and you are never renting access to your own numbers. That is also why a handover is possible at all — nothing sits behind a SellerUp account that we could switch off.
Can it work with the tools we already have?
Yes, and that is usually cheaper than replacing them. We integrate what already earns its place — spreadsheets your team trusts, an ERP, delivery services, BI tools you hold licences for — and build only the part that is missing. Replacing a working tool for the sake of tidiness is not something we will bill you for.
How does a build start, and how long does it take?
It starts with a strategy session or a process and data audit, which ends in a written plan you can execute with us or without us. From there a first working piece usually lands in weeks and a full build in two to four months, depending on how many platforms and cost sources are in scope. Describe the task and we reply within one business day.
What does it cost?
Every build is quoted per project rather than from a price list: the number of platforms and cost sources to integrate, how much of your process is genuinely bespoke, and whether we stay on support or hand the system over all change the figure. Describe the process that hurts and we come back with a range within one business day.
Custom is not automatically the right answer — sometimes a subscription is cheaper and faster. Compare custom software with SaaS, an agency and an in-house hire
Recent work
Three problems we built solutions for.
Each case is a production system shipped for a real seller. Short summaries below — full write-ups linked under each card.
02Operations · Amazon
Custom internal system for an Amazon seller.
Server-side platform unifying stock, orders, suppliers, and resource planning. One source of truth for the operations team — instead of seven scattered spreadsheets.
Request
Tell us what tool you need.
Describe the process that hurts and what success would look like. We reply within one business day.
- Reply within 1 business day
- Honest go / no-go answer
- No “boilerplate proposal”