> ## Documentation Index
> Fetch the complete documentation index at: https://docs.usecharlie.ai/llms.txt
> Use this file to discover all available pages before exploring further.
# Overview
> Understand how order routing controls which locations fulfill orders and in what priority
Order routing determines **where** your orders are fulfilled from when multiple locations have available inventory. Charlie extends Shopify's native order routing with powerful rules that let you optimize fulfillment based on your business needs.
## Constraints vs Routing rules
Charlie offers two complementary ways to control fulfillment:
**Block** locations from fulfilling specific orders. Hard rules that completely remove locations from consideration.
**Prioritize** locations for fulfillment. Soft rules that rank locations by preference without blocking any.
| | Fulfillment Constraints | Order Routing Rules |
| ----------------- | ------------------------------------------------ | ------------------------------------------- |
| **Effect** | Blocks locations entirely | Ranks locations by priority |
| **When no match** | Checkout blocked, no shipping options | Falls back to next priority |
| **Risk level** | High (can block checkout) | Low (always has fallback) |
| **Use case** | Hard business requirements | Optimization preferences |
| **Example** | "Fragile items can NEVER ship from small stores" | "Prefer warehouse first, then large stores" |
**Rule of thumb:** Use constraints when a location **must not** fulfill certain orders under any circumstances. Use routing rules when you **prefer** certain locations but can accept alternatives.
## How order routing works
When a customer reaches checkout, Shopify processes fulfillment in this order:
```mermaid theme={"system"}
flowchart TD
A[Customer checkout] --> B[Apply Fulfillment Constraints]
B --> C{Any locations
remaining?}
C -->|No| D[❌ Checkout blocked]
C -->|Yes| E[Apply Order Routing Rules]
E --> F[Rank remaining locations]
F --> G[Check inventory at top-ranked location]
G --> H{Stock
available?}
H -->|Yes| I[✅ Fulfill from this location]
H -->|No| J[Try next-ranked location]
J --> G
```
## Where to configure order routing
Charlie's order routing rules are configured in **Shopify's Order Routing settings**. You can access these settings either from Charlie or directly from Shopify.
Charlie's routing rules are **Shopify Functions** that integrate directly into Shopify's Order Routing. This means you can combine Charlie's rules with Shopify's native routing options in one place.
1. Open the Charlie app
2. Go to **Settings**
3. Under **Order management**, click **Order routing**
This takes you directly to Shopify's Order Routing settings.
1. In your Shopify admin, go to **Settings**
2. Click **Shipping and delivery**
3. Scroll to **Order routing**
Both paths lead to the same place — choose whichever is most convenient for you.
### Enable or disable rules
Each routing rule can be **enabled or disabled** independently. This allows you to:
* **Build rules in advance** without affecting live orders
* **Test configurations** before activating them
* **Quickly disable a rule** if issues arise, without deleting it
* **Prepare for peak seasons** by pre-configuring rules and enabling them when needed
Create and configure your routing rules ahead of time, then enable them when you're ready to go live. This is especially useful for seasonal strategies like Black Friday.
## Available routing rules
Charlie provides eight types of order routing rules:
Create prioritized groups of locations. Orders are routed to the highest-priority group with available stock.
**Use cases:**
* Prefer warehouses over stores
* Prioritize locations by region
* Create fallback hierarchies
**Example:** Group 1 (Central Warehouse) → Group 2 (Regional Warehouses) → Group 3 (Stores)
[Learn more →](/order-routing/ranked-location-groups)
Prioritize locations based on what products are in the cart.
**Use cases:**
* Route specific brands to dedicated locations
* Prioritize collections to certain stores
* Handle product-specific fulfillment preferences
**Example:** Premium products → Flagship stores first
[Learn more →](/order-routing/product-rules)
Prioritize locations based on who is placing the order.
**Use cases:**
* B2B customers → Warehouse priority
* VIP customers → Premium locations
* Regional customers → Local stores
**Example:** B2B orders → Distribution center first
[Learn more →](/order-routing/customer-rules)
Prioritize locations based on cart properties like quantity, amount, or line item attributes.
**Use cases:**
* Large orders → Bulk fulfillment centers
* High-value orders → Secure locations
* Gift-wrapped items → Stores with gift services
**Example:** Orders > 10 items → Warehouse first
[Learn more →](/order-routing/cart-rules)
Automatically prioritize locations with more available stock.
**Use cases:**
* Reduce split shipments
* Balance inventory across locations
* Prefer locations that can fulfill complete orders
**Example:** Location with most stock → Highest priority
[Learn more →](/order-routing/inventory-rules)
Prioritize locations based on their current fulfillment capacity.
**Use cases:**
* Avoid overloading busy locations
* Balance workload during peak periods
* Route away from locations at capacity
**Example:** Location with most available capacity → Highest priority
[Learn more →](/order-routing/capacity-rules)
Prioritize locations based on how many open, unfulfilled orders they currently have. Optionally block locations once their backlog crosses a threshold.
**Use cases:**
* Balance pipeline depth across stores
* Protect small locations from overload
* Combine soft preference (short backlog) with hard cap (block when backlog exceeds threshold)
**Example:** Location with fewer pending orders → Higher priority
[Learn more →](/order-routing/backlog-routing)
Rank locations into performance tiers by a metric like average time to ship, and route to your fastest performers first.
**Use cases:**
* Prefer locations that ship fastest
* Steer volume toward your best-performing stores
* Combine speed with stock and capacity signals
**Example:** Location shipping in under 24h → Higher priority
[Learn more →](/order-routing/analytics-metric)
## Combining rules
You can use multiple routing rules together. Shopify evaluates them in the order you set:
```mermaid theme={"system"}
flowchart LR
A[All locations] --> B[Rule 1:
Customer Rules]
B --> C[Rule 2:
Inventory Rules]
C --> D[Rule 3:
Capacity Rules]
D --> E[Final ranking]
```
The order matters! Rules earlier in the list have higher priority. If Rule 1 assigns a location rank 1, subsequent rules refine the ranking within that constraint.
### Example: Optimized B2B fulfillment
A wholesaler wants to:
1. Route B2B orders to warehouses first
2. Among warehouses, prefer those with more stock
3. Avoid locations at capacity
**Setup:**
1. **Customer Rules:** B2B customers → Warehouse group priority
2. **Inventory Rules:** Rank by available stock
3. **Capacity Rules:** Deprioritize locations at capacity
**Result:** B2B orders go to the warehouse with the most stock that isn't at capacity.
## Constraints + Routing: Working together
For complex fulfillment strategies, combine constraints and routing rules:
| Layer | Type | Purpose |
| ----- | ----------------- | ----------------------------------------------- |
| 1️⃣ | **Constraints** | Remove ineligible locations (hard requirements) |
| 2️⃣ | **Routing rules** | Rank remaining locations (optimization) |
| 3️⃣ | **Shopify** | Select location with stock at best rank |
### Example: Fragile items strategy
**Business requirement:** Fragile items should never ship from small stores, and should prefer the central warehouse.
**Setup:**
1. **Fulfillment Constraint (Product Rule):**
* Condition: Products in "Fragile Items" collection
* Filter: Exclude locations tagged `small-store`
* Effect: Small stores are **blocked**
2. **Order Routing (Ranked Groups):**
* Group 1: Central Warehouse
* Group 2: Large stores
* Effect: Central warehouse is **preferred**
**Result:**
* Small stores can never fulfill fragile items (constraint)
* Central warehouse is tried first (routing)
* Large stores are the fallback (routing)
* If all are out of stock, checkout is blocked (no eligible location)
## Best practices
Routing rules are safer since they never block checkout. Add constraints only for hard requirements.
Inventory-based routing automatically reduces split shipments and balances stock levels.
Add capacity rules to prevent overloading locations during peak periods.
Verify your routing strategy with test orders before high-volume periods like Black Friday.
## Related
Block locations from fulfilling specific orders
Set up tags to use in your routing rules
Configure capacity limits for your locations