Implementation of Multichannel Sales (Omnichannel) on the Website

How to Implement Multichannel Sales (Omnichannel)?

Imagine: a client orders a chair on the website, picks it up in the store an hour later, but the chair remains available online — already sold. Or a promo code works only online, not in the app. These are classic consequences of fragmented channels. We integrate multichannel sales so that the customer sees a unified picture: identical prices on website and marketplaces, order history in the personal account, and the ability to return an item from Ozon via the store. This is achieved via API, message broker (RabbitMQ), and unified profiles in PostgreSQL.

Why Is Omnichannel More Than Multiple Stores?

Many think: "Connected marketplace APIs — that's omnichannel." In reality, chaos emerges: the product is on the website but out of stock on Ozon. Or a discount applies only offline. The root issue is disparate data sources: prices, stock, orders live in different systems without a common key. We solve this through Unified Commerce Core — a microservice holding inventory, customers, and promotions in one place. All channels refer to it. This eliminates N+1 queries and conflicts. For deeper understanding, see external reference.

What Challenges Does Omnichannel Solve?

Unified Customer Profile and Data Synchronization: The customer registers on the website, buys via WB, and returns in the store — the system must recognize it's the same person. Without this, personalization and order history are impossible. We implement Customer Identity Resolution through a chain: email → phone → name+address.

class CustomerIdentityResolver
{
    public function resolve(array $customerData, string $source): Customer
    {
        $customer = null;
        if (!empty($customerData['email'])) {
            $customer = Customer::where('email', $customerData['email'])->first();
        }
        if (!$customer && !empty($customerData['phone'])) {
            $normalized = $this->normalizePhone($customerData['phone']);
            $customer   = Customer::where('phone_normalized', $normalized)->first();
        }
        if (!$customer) {
            $customer = Customer::create([
                'name'             => $customerData['name'],
                'email'            => $customerData['email'] ?? null,
                'phone_normalized' => $normalized ?? null,
                'source_first'     => $source,
            ]);
        }
        $customer->channelIds()->updateOrCreate(
            ['channel' => $source],
            ['external_id' => $customerData['id'] ?? null]
        );
        return $customer;
    }
}

Order history merges into one table linked to customer_id. Promotion management ensures a promo code created for the website also works on the marketplace if the channel is allowed. Channel-based reservation uses fixed percentages: site 40%, ozon 30%, wb 20%, buffer 10%. This approach reduces overbooking risk by up to 60% compared to a full pool.

class OmnichannelPromotion
{
    public function apply(string $promoCode, Order $order): void
    {
        $promo = Promotion::where('code', $promoCode)->first();
        if (!in_array($order->source, $promo->applicable_channels)) {
            throw new PromoNotApplicableException("Promo code not valid for {$order->source}");
        }
        $discount = $promo->calculateDiscount($order->total);
        $order->applyDiscount($discount, $promoCode);
        $promo->increment('used_count');
    }
}

Integration Approaches and Reservation Strategies

We choose the third option — lowest latency and good scalability. Event-driven is 2–3× faster than ETL for stock sync. More about CDC: official documentation.

Work Process and What's Included

1. Analysis — review architecture, channels, data volumes, business rules.
2. Design — data model, API specs (OpenAPI), exchange scheme.
3. Implementation — write Core, adapters, tests (unit + integration).
4. Testing — end-to-end scenarios: order on website, cancel in app, return on marketplace.
5. Deployment — roll-out per channel, monitoring via Grafana.

We guarantee real-time data consistency. Our engineers have over 5 years of experience in distributed systems. For a furniture store chain, we integrated 5 channels, reducing return rates by 25% through accurate stock display. Typical project cost: $15,000–$40,000 depending on number of channels and complexity. Clients save an average of $50,000 annually from reduced overstock and returns.

• Development of Unified Commerce Core (inventory, customers, orders, promotions).
• Integration with 3+ channels (website, marketplaces, mobile app).
• API documentation and data schemas.
• Load testing and optimization.
• Training for the client's team.

Timelines & Pricing

Basic system for 3 channels: 20–30 working days. For 5+ channels: up to 50 days. Pricing is individual after an audit. Get a consultation to evaluate your project.

Our Experience

We have completed 15+ omnichannel projects for e-commerce. Clients include stores with monthly turnover from $100,000. Our engineers have over 5 years of experience. Contact us — we will help determine the optimal architecture.

How to Avoid Discrepancies in Commission Calculations

Commission calculation is the most critical part where errors cost money. Rule one: never store commission as a derived value, always as a fact. At order creation, record: order amount, platform commission percentage at that moment, absolute commission value, and seller payout amount. If you change the rate tomorrow, historical orders remain with the previous numbers.

Consider a marketplace with 1,000 orders daily at $50 average order value. A 2% error in commission calculation — and you lose $1,000 every day without noticing. Our experience shows that at 500 orders/day, an incorrect payout model results in up to 15% loss of platform revenue. We have solved this for 50+ projects, from niche B2B to horizontal retail. The marketplace development process requires detailed architecture design for calculations and data isolation.

Commission Models (we use one of or combine)

We use Stripe Connect as the baseline standard. Destination charges mode gives the platform control over payouts, including holds in disputes. Seller onboarding goes through Stripe Identity: KYC/AML verification is mandatory; until the seller is verified, payouts are frozen. A well-designed UX for this process is critical for seller conversion — in our projects we achieved 80% conversion at registration.

What commission model suits your marketplace?

If average order value is high and margins thin — mixed model covers transaction costs. For B2B with volume discounts — tiered works best. Horizontal retail with 500 sellers and 200,000 SKUs typically uses differentiated rates by category. The wrong model can cost 3–5% of GMV, which directly hits your bottom line.

Why Multitenancy Architecture Is Critical for Data Isolation

The first step is choosing a multitenancy architecture. In shared-schema mode, all sellers are in the same tables with vendor_id. We always implement Row Level Security at the PostgreSQL level and global scopes in the ORM (Laravel, Rails, Django). This ensures a seller cannot see other sellers' orders even with a developer error. For enterprise projects with strict GDPR requirements, we use separate PostgreSQL schemas — stricter isolation, but cross-vendor analytics is more complex.

How to Handle Inventory Without Race Conditions

Two buyers simultaneously add the last item to their cart. Who gets it? Use optimistic locking when creating the order:

UPDATE inventory 
SET reserved = reserved + 1 
WHERE product_id = ? AND (quantity - reserved) >= 1

Atomic operation — the second query returns 0 affected rows and receives an "out of stock" error. Typical schema for high-traffic marketplaces. Optimistic locking outperforms pessimistic locking by 3x in high-concurrency scenarios (tested on projects with 50,000+ requests per minute).

Comparison of Catalog Approaches

For a niche B2B marketplace, we often choose per-vendor — faster launch. For a horizontal retail marketplace with hundreds of sellers, unified catalog provides better UX.

Moderation Pipeline: Automated and Manual Verification

A marketplace is responsible for seller content. Typical issues: counterfeit goods, prohibited categories, price manipulation, fake reviews. We build a three-tier pipeline:

1. Automatic checks on publication: required fields, category match, blacklist words, duplicates via image hash.
2. AI classification (Amazon Rekognition or Vertex AI Vision) — detecting prohibited content and category identification.
3. Manual review queue for flagged items.

State machine: draft → pending_review → active / rejected → suspended. Each transition is an event with reason and moderator. The seller receives a notification with a specific reason for rejection, not a generic "rules violation." Review verification is mandatory — only after confirmed purchase. Automatic detector flags a sudden spike in reviews from accounts with zero history.

Search and Recommendations

Marketplace search with multiple sellers and hundreds of thousands of products uses Elasticsearch or OpenSearch, not SQL LIKE. Vector search for semantics, faceted filtering via aggregations. Personalized feed based on collaborative filtering. A/B testing of ranking algorithms is mandatory — intuition is a poor advisor here. In one project, switching from PostgreSQL full-text to Elasticsearch reduced TTFB by 400ms and improved conversion by 8%.

Marketplace Development Process

Marketplace development is iterative. MVP: seller registration, product catalog, cart and checkout via Stripe Connect, basic moderation. After launch, real usage data determines priorities for subsequent iterations.

Typical order:

• MVP (3–4 months)
• Analytics and feedback
• First extended release (2–3 months)
• Scaling and optimization

Timeline and Budget

• Marketplace MVP (catalog, checkout, basic seller profiles): 3–5 months.
• Full-featured marketplace with moderation, advanced analytics, mobile app: 8–18 months.
• Adding marketplace functionality to an existing e-commerce: 2–5 months.

Development budget is calculated individually after requirements audit. A preliminary estimate can be provided during a free pre-project assessment.

What's Included

• Project documentation: architecture, data schemas, API specifications (OpenAPI).
• Access to repository, CI/CD, deployment documentation.
• Training for the client's team on platform operation.
• Technical support for the first month after launch.

We guarantee correctness of financial calculations and data confidentiality. Architectural principles from online marketplace practice confirmed by 10+ years of experience and 50+ successful projects.

Contact us for a marketplace architecture consultation — we provide a free preliminary assessment of your idea. Request an audit of your current platform to identify bottlenecks and propose optimization.