When using Postman in developing environment, and knowing the SDK HTTP calls, can Postman be used as an alternative to the SDK library to calculate a treatment for a given split?
No. While Postman can use the same HTTP calls to download the splits definitions from the Split cloud, it needs to use the same Murmur hash that all SDKs use to assign a bucket (from 1 to 100) for a given user id, then apply the split rules and conditions based on that bucket.
This process is done by the SDK locally, and not through the Split cloud, which is why we need the SDK libraries.
As a workaround, Split Evaluator can be installed in the environment and Postman can use HTTP get requests to fetch a treatment for given split and user id. The Split evaluator will perform the calculation and respond back to Postman with the corresponding treatment. Check out this link for more info.