Rashmi, it's quite easy to convert a Json String into a Json Object using UiPath. Just follow the below mentioned steps:
1. Create a new Process and go to Manage Packages. Search for UiPath.Web.Activities package in Official section and install it by clicking on Save.
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2. Now drag Deserialize JSON activity and mention the JSON string you wish to convert into Object.
3. Store the output of Deserialization into outputJSON, a JObject type variable.
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And you have your JSON object.