9 Things I Got Wrong About Building E-commerce Systems (That I Had to Learn the Hard Way)

K

Khaled waleed

Guest

๐Ÿ‘‹ A Quick Intro​


I've been building and contributing for e-commerce platforms for the majority of my career for startups, multi-vendor marketplaces, and fast-growing businesses. During this time I made a lot of mistakes, made huge money loses I'm not proud of :D but most importantly I solved even more problems thus I learned what works and what doesn't.

This article is a simple summary of the key things Iโ€™ve learned. If youโ€™re building an e-commerce system (whether for physical goods, digital goods, or services) I hope this helps you avoid the same mistakes and design better systems from the start.

๐Ÿ’ฐ 1. Just storing the final price is a long-term liability​


Most platforms only store what the customer paid. It feels enough โ€” until finance starts asking questions like:

  • โ€œWhat was our margin after fees and discounts?โ€
  • โ€œWhy do two identical orders show different profitability?โ€
  • โ€œHow much did this campaign really cost us?โ€

And thatโ€™s when you realizeโ€ฆ you didnโ€™t track any of it.

Why it matters:

If you only store the final paid amount, you lose visibility into how that price was built. And worse, if prices change over time, you have no way to go back and understand what the price was at the time of purchase. Youโ€™ll be blind to your own data โ€” and reports will become guesswork.

What to do instead:

Break the price down into its components: base cost, discounts, shipping, tax, fees, etc.

And just as importantly โ€” store historical pricing at the time of the order. Even if your pricing model evolves, the record of what was sold, at what cost and margin, should never change.

โš™๏ธ 2. Not everything needs to go through a sprint​


This one hits hard in growing teams.

Sometimes ops just needs:

  • A way to export tracking numbers
  • A quick CSV parser
  • A hacky tool to clean vendor data or trigger a re-sync

But instead, we say:

โ€œLetโ€™s write a ticket โ†’ estimate it โ†’ groom it โ†’ prioritize it โ†’ plan it โ†’ build it.โ€

And while we plan, ops suffers.

Why it matters:

The difference between a 2-week feature and a 2-hour tool can be one hour of autonomy โ€” and your willingness to move fast.

What to do instead:

When the solution is obvious and internal, build it. A dirty HTML file that exports shipment IDs can save days of manual work โ€” and earn a lot of trust.

๐Ÿ‘‰ Not everything needs a roadmap. Some things just need a quick win.

๐Ÿ“ฆ 3. Inventory is not a number โ€” itโ€™s a history​


โ€œ10 in stockโ€ looks fine โ€” until someone asks:

  • โ€œWhere did the stock come from?โ€
  • โ€œWas it sold or returned?โ€
  • โ€œWhy are we off by 3 units?โ€

And thereโ€™s no way to answer.

Why it matters:

Ops teams rely on traceability. If you canโ€™t explain changes, your stock levels are just guesses.

What to do instead:

Track every inventory movement โ€” what changed, when, why, and who did it. Youโ€™ll prevent hours of manual tracing and avoid losing trust from internal teams.

๐Ÿงพ 4. If you canโ€™t reconcile it, you canโ€™t trust it​


Everything looks good in the dashboard โ€” until finance or vendors ask:

  • โ€œWhy is Stripe reporting less than the platform?โ€
  • โ€œWhy didnโ€™t this vendor receive their full payout?โ€
  • โ€œWhy is the total off by 3% this month?โ€

Why it matters:

If your numbers canโ€™t be matched with bank or gateway records, no one will trust your reports โ€” no matter how nice they look.

What to do instead:

Track the entire money flow โ€” including gateway fees, commissions, VAT, and vendor shares. Your system should act like a financial ledger behind the scenes.

๐Ÿšš 5. Delivery logic must be swappable​


You start with one delivery provider and build everything around them. Then ops says:

  • โ€œWeโ€™re switching to another courier.โ€
  • โ€œThis one needs label printing.โ€
  • โ€œWe need to support restaurant delivery.โ€

And now youโ€™re rebuilding your delivery logic all over again.

Why it matters:

Tightly coupling your system to one provider makes you inflexible. Ops canโ€™t move fast, and your dev team becomes a bottleneck.

What to do instead:

Design your delivery engine to support multiple providers. Think of each integration as pluggable โ€” because they will change.

๐Ÿงฎ 6. ERP integration will expose everything you skipped​


At some point, someone will say:

โ€œCan we sync orders and payouts into the accounting system?โ€

Thatโ€™s when you realize:

  • Discounts and fees are all lumped together
  • Thereโ€™s no mapping to account codes or payment types
  • Tax is handled manually
  • General Ledger integration is near impossible

Why it matters:

You canโ€™t close the books โ€” or scale operations โ€” without clean financial data.

What to do instead:

Even before ERP is in scope, structure your financial records to reflect reality: revenue, cost, tax, fees, commissions, etc.

๐Ÿ•“ 7. Status history is more valuable than current status​


Everyone looks at the current order status. But when problems happen, people ask:

  • โ€œWhen did it move to paid?โ€
  • โ€œHow long was it stuck in shipped?โ€
  • โ€œWho changed it manually?โ€

And you realize: you donโ€™t know.

Why it matters:

A single status field tells you nothing about the journey. And thatโ€™s where the root causes live.

What to do instead:

Track every status change โ€” timestamp, user, and reason. This is how you trace issues, measure SLAs, and answer vendor questions with confidence.

๐Ÿ‘€ 8. No audit logs? Youโ€™ll regret it​


In small teams, you can ask around:

โ€œDid someone edit this?โ€

โ€œWho updated the payout?โ€

But in a growing company, across shifts and regions โ€” thatโ€™s impossible.

Why it matters:

Without audit logs, everything becomes a guessing game. And that slows teams down.

What to do instead:

Log every change to sensitive data: orders, inventory, prices, vendors. This isnโ€™t about control โ€” itโ€™s about trust, transparency, and traceability.

๐Ÿ“Š 9. Reporting is not analytics​


Early on, it feels enough to just show raw data in dashboards: sales totals, order counts, top products. But soon, stakeholders start asking:

  • โ€œWhich marketing channel drove the highest-margin sales?โ€
  • โ€œWhich customers are profitable vs. loss-making?โ€
  • โ€œWhatโ€™s the true CAC vs. LTV?โ€

And your system canโ€™t answer.

Why it matters:

Dashboards with raw numbers donโ€™t drive decisions. Without context and proper breakdowns, data becomes noise โ€” not insight.

What to do instead:

Design reporting with analytics in mind:

  • Tag data by source (campaign, channel, customer segment)
  • Track cohorts and profitability, not just revenue
  • Build the ability to drill down, not just sum up

Good analytics will drive better product decisions, marketing spend, and operational efficiency.

โœ… Final thoughts​


Most e-commerce systems donโ€™t collapse because of a bug in the code. They collapse when teams are forced to scale on top of fragile foundations.

In my experience, the systems that thrive over time are the ones that are easy to explain to others, trusted across departments, and resilient to change. You can trace every order. You can justify every payout. You can onboard new team members without a wall of confusion.

These platforms arenโ€™t just โ€œbuiltโ€ โ€” theyโ€™re designed with care, with structure, and with a clear understanding of whatโ€™s coming next.

If youโ€™re in the middle of building, scaling, or even cleaning up an e-commerce platform, I hope these lessons help you think a few steps ahead.

And if youโ€™ve been through some of this already โ€” Iโ€™d love to hear what you learned along the way.

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