Q:

How to test migrated data in salesforce?

We are performing a data migration in salesforce application and i am going to validate the migrated data (including schema at field, table and database level). I planned to use REST API but SQL Server Integration Services tool is also advised in our organisation. I feel creating test library that consumes the REST API is more efficient as we can validate the schema and data and do the comparison through code. But i need expert's advice which one we can use and what can be the best approach. I cannot use any third party software due to license constraint.
The  data in question here are being migrated from multiple salesforce orgs to one single org.

A:

Your requirement seems like a kind of unique requirement specific to your org/company. 
While it may be achievable with standard ETL tools (be it Sql Server tool or other ETL tools), but effort it takes to make them do the procedural logic (like fetch Object metadata from source org and destination org, and compare fields etc) may not be worth it.
I would use either Rest API or Soap API to fetch the data you looking for and use your favorite GPL language to implement what you looking for.
If you are using Java, wsc is a good choise. If you are using Node, then jsforce would be an option.

