Here is the link to our API documentation (you should be able to access dev portal with your Linnworks credentials)
1. In dev portal create System Integration application. https://developer.linnworks.com
2. Install it on necessary Linnworks account using installation URL - provided in dev portal.
3. On installation you will receive token - static parameter that you will have to pass with application Id and Application Secret (both visible in dev portal) to this call http://apps.linnworks.net/Api/Method/Auth-AuthorizeByApplication
4. Pull open orders - http://apps.linnworks.net//Api/Method/Orders-GetOpenOrders
- Samples of filters: https://help.linnworks.com/solution/articles/7000007478-getopenorders-api-call-filter-samples
5. Update shipping information of open order - http://apps.linnworks.net//Api/Method/Orders-SetOrderShippingInfo
6. Process orders - http://apps.linnworks.net//Api/Method/Orders-ProcessOrdersInBatch
7. If you want to get more detailed information about open or processed orders - http://apps.linnworks.net//Api/Method/Orders-GetOrdersById
8. Adjust stock levels:
9. Getting the list of available locations and their IDs - http://apps.linnworks.net/Api/Method/Inventory-GetStockLocations