e-commerce multi-marketplace aggregation manual process risk
Common Mistakes Companies Make When Aggregating Multi-Marketplace CSVs by Hand Every Week
Published: 2026-07-29
In short
Most sellers running multiple marketplaces start out by exporting CSVs from each marketplace's admin dashboard and aggregating them by hand in Excel. This isn't a problem while the number of marketplaces and products is small, but as they grow, transcription errors, inconsistent aggregation rules, and dependence on a single person become increasingly likely. The cause isn't the skill of the person doing the work — it's the structure of manually reconciling data in different formats across marketplaces.
Introduction: CSV aggregation is an operation that "works well at first"
Most sellers who are new to running multiple marketplaces start by downloading CSVs from each marketplace's admin dashboard and pasting them into Excel or a spreadsheet to tally revenue. While there are only one or two marketplaces and few products, this doesn't cause major problems. But as the number of marketplaces and products grows, this same process gradually starts to strain under its own weight.
The mistakes that show up aren't a matter of the person's skill
- Transcription errors: reconciling CSVs by hand every week, each with different column layouts and product-code formats per marketplace, makes copy-paste slips and manual number-entry errors common.
- Inconsistent aggregation rules: rules like "whether to include returns" or "when to deduct cancellations" can drift subtly depending on who's doing the work, or from week to week.
- Dependence on one person: which sheet and which column means what ends up implicitly baked into the structure of an Excel file, making it hard for anyone but the person who built it to maintain.
- Delayed updates: because the manual workload is heavy, aggregation slips from weekly to biweekly or monthly, delaying how quickly anomalies get noticed.
These aren't the result of carelessness — they're inherent to the structure of manually reconciling data in different formats across marketplaces. The more marketplaces you add, the more the required reconciliation work multiplies.
Why it's hard to notice that aggregation has become dependent on one person
The danger of this kind of dependency is that it doesn't surface as long as the person handling it keeps things running smoothly. It's usually only when that person transfers or leaves that everyone discovers nobody understands how the Excel file was actually built. When an aggregation process depends on one individual's know-how, the operation is always one departure away from grinding to a halt.
The real fix is to stop aggregating by hand
Trying to compensate for transcription errors and single-person dependency through sheer attentiveness only goes so far. The real fix is to reduce the manual work of reconciling CSVs from each marketplace and replace it with a system that automatically consolidates the data in one place. If aggregation rules — how returns are handled, cutoff dates, and so on — are fixed at the system level, it also becomes much harder for the rules to drift from person to person.
Related reading
The Real Cost of Continuing to Aggregate Multi-Marketplace Numbers in Excel
Beyond manual errors, this piece looks at how to treat the time spent on aggregation itself as a real cost.
Suiliv Integrated Dashboard
Just send each marketplace's CSVs — the data is aggregated automatically with fixed rules applied.
Frequently asked questions
Q. Can training staff prevent CSV aggregation mistakes?
Training can help to some extent, but as the number of marketplaces and products grows, the sheer volume of reconciliation work increases, making it hard to bring the error rate to zero as long as it's done manually. Reducing the aggregation process itself is the more fundamental fix.
Q. How can I tell if our aggregation process has become dependent on one person?
Ask yourself: if the person who currently handles aggregation were out for a week, could someone else reproduce the same result with the same accuracy? If the answer is no, you're carrying that dependency risk.
Q. Where should we start?
Rather than trying to automate everything at once, start by documenting your aggregation rules — how returns are handled, cutoff dates, and so on. From there, it's realistic to gradually replace manual steps with automatic data consolidation wherever possible.
Facing this kind of challenge?
For sellers running two or more of Rakuten, ZOZOTOWN, and their own store (Shopify), we build a dashboard that consolidates data across marketplaces and deliver a weekly AI-annotated report focused on the metrics that matter for your industry. A free diagnostic is also available to check your current data-integration status.