ERP 2.0 – Marketplace API Integrations, Catalog Management & Automatic Stock Synchronization

We currently have an ERP 2.0 connected to multiple marketplaces through API integrations.
We need to complete, adapt, and validate several marketplace functionalities within ERP 2.0, specifically related to:
1. Walmart integration
2. Sears integration
3. Automatic stock synchronization across all currently integrated marketplaces, including Amazon
The freelancer will work exclusively on ERP 2.0 and the existing marketplace integrations/codebase.
1. Walmart Integration
A. Order Dispatch
1. Sales Document Generation (Remisión)
When a Walmart order is received, ERP 2.0 must automatically generate the corresponding sales document (Remisión).
The document comments must include:
- Order number
- Shipping/tracking number
2. Shipping Label Download
ERP 2.0 must retrieve and allow the user to download the Walmart shipping label associated with the order in PDF format.
3. Correct Pricing in the Sales Document
The sales document must calculate the correct price considering:
- Marketplace sales commission: 15%
- Shipping cost: $180 MXN
The following calculator can be used as a reference to validate the calculation:
https://mercasync.com/calculadora-margen/
The final values generated in ERP 2.0 must follow the required business logic.
B. Product Cataloging
ERP 2.0 must allow products to be created and published on Walmart through its API.
The cataloging functionality must support:
- Individual product creation
- Bulk product creation
- Simple products
- Variable products / products with variants
Simple Products
The system must allow the creation and publication of products that contain a single SKU without variations.
All required marketplace attributes must be correctly submitted through the API.
Variable Products
The system must also allow the creation and publication of products with multiple variants under the same parent product.
For example, variants may include:
- Size
- Color
- Style
- Other marketplace-supported variation attributes
Each variant must be correctly associated with its corresponding SKU, stock, price, attributes, images, and other required information.
Catalog Validation
The system must process and display API responses and errors so that we can identify:
- Successfully created products
- Rejected products
- Missing required attributes
- Invalid information
- Variant errors
- Image errors
- Other marketplace API errors
2. Sears Integration
A. Order Dispatch
1. Sales Document Generation (Remisión)
ERP 2.0 must correctly generate the corresponding sales document for Sears orders.
The document comments must contain:
- Order number
- Shipping/tracking number
The existing implementation must be reviewed and validated to ensure that it works correctly.
2. Shipping Label Download
ERP 2.0 must retrieve and allow the user to download the Sears shipping label associated with the order in PDF format.
3. Correct Pricing in the Sales Document
The pricing logic must consider:
- Marketplace sales commission: 18%
- Shipping cost: $180 MXN
Reference calculator:
https://mercasync.com/calculadora-margen/
The implementation must be reviewed and validated to ensure that the final values are calculated correctly.
B. Product Cataloging
ERP 2.0 must allow products to be created and published on Sears through its API.
The cataloging functionality must support:
- Individual product creation
- Bulk product creation
- Simple products
- Variable products / products with variants
Simple Products
The system must allow products with a single SKU and no variations to be created and published correctly.
Variable Products
The system must allow products with multiple variants to be created and correctly grouped under the corresponding parent product.
Each variant must maintain its corresponding:
- SKU
- Price
- Stock
- Attributes
- Images
- Variation values
- Other information required by the marketplace API
Current Image Issue
There is currently an issue with product images.
Products can be uploaded successfully; however, the images appear broken on the marketplaces unless they are first uploaded to the T1 server.
As part of this project, the freelancer must:
1. Analyze the root cause of the issue.
2. Propose an appropriate technical solution.
3. Implement the agreed solution.
4. Ensure that images submitted through the marketplace APIs are publicly accessible and correctly processed.
5. Avoid unnecessary manual image-upload processes whenever technically possible.
3. Automatic Stock Synchronization – All Marketplaces
A centralized automatic inventory synchronization system must be implemented in ERP 2.0 for all marketplaces currently integrated with the ERP, including Amazon, Walmart, and Sears.
Main Objective
ERP 2.0 must be the primary source of truth for available inventory by SKU.
Whenever the available stock of a SKU changes in ERP 2.0, the updated quantity must automatically be sent through the corresponding API to every marketplace where that SKU is published.
Example
If SKU 001 has 11 units available in ERP 2.0, every applicable marketplace where SKU 001 is published must receive the corresponding stock quantity.
If the inventory later changes from 11 to 8 units, ERP 2.0 must automatically send the new inventory quantity to all applicable marketplaces.
The functionality must include at least:
- Amazon
- Walmart
- Sears
- All other marketplaces currently integrated with ERP 2.0 that support inventory updates through API
Stock Synchronization Requirements
1. Automatic Updates
Inventory changes in ERP 2.0 must automatically trigger the corresponding marketplace inventory updates without requiring manual intervention.
2. SKU Mapping
The system must correctly identify the relationship between the SKU in ERP 2.0 and its corresponding product/listing on each marketplace.
3. Multiple Marketplaces
A single SKU may be published simultaneously across multiple marketplaces.
When its inventory changes, the new stock must be propagated to all applicable marketplace listings.
4. Amazon Integration
Amazon must be explicitly included in the automatic inventory synchronization functionality using the appropriate API available for the existing Amazon integration/account.
5. Zero Stock
When a SKU reaches 0 available units, ERP 2.0 must send a stock quantity of 0 to the corresponding marketplaces whenever supported by their APIs.
This is required to reduce the risk of overselling.
6. Error Logging
If a marketplace rejects an inventory update or an API error occurs, ERP 2.0 must log enough information to diagnose the problem, including:
- Marketplace
- SKU
- Stock quantity sent
- Date/time
- API response or error message
7. Retry Mechanism
The system must include an appropriate retry mechanism for inventory updates that fail due to temporary API or communication errors.
The implementation must avoid unnecessary duplicate updates.
8. Validation
The functionality will not be considered complete simply because ERP 2.0 successfully sends an API request.
Testing must confirm that the inventory update is successfully processed by the corresponding marketplace.
Before development begins, the freelancer must identify and document all marketplaces currently integrated with ERP 2.0 that support inventory updates through API.
General Technical Requirements
The freelancer must work exclusively on ERP 2.0 and its existing codebase and integrations.
Each functionality must be tested through its complete workflow where applicable:
Marketplace API → ERP 2.0 → Processing → Document / Catalog / Inventory → Marketplace API Response
The implementation must include:
- Proper error handling
- API response validation
- Sufficient logging for troubleshooting
- Testing before deployment to production
- Protection of existing working integrations and functionality
- Clean and maintainable code
Any modification made as part of this project must not break existing integrations or ERP 2.0 functionality.
All code must be delivered through the repository and branch specified for the project.