Hey @Fredi , I believe the answer for your problem is the processor UpdateRecord.   Update record allows you to directly manipulate the fields in your file content. You add dynamic properties to the processor where the key of the property is /<field> (so in your case, '/api_value'), and in the value of this dynamic property you can write down some logic to determine what value to insert into api_value.   In the processor, there is a field called "Replacement Value Strategy", which defines how the value of the property will be read. If you set this to "Record Path Value", it means you can now give a path to a different field in your file (url_value!) - I can't test this right now because I'm not at my office, but I'm not entirely sure whether you can manipulate the result after giving a record path (to extract the api_value from the evaluated url_value).   Regardless, I'm just about 100% sure this can be done with two processors - One EvaluateJsonPath to extract the url_value into an attribute, then UpdateRecord that uses the 'Literal Value' replacement strategy - with this strategy, you can just add a property with key '/api_value' and value '${url_value}' (or whatever attribute name you gave to the extracted url_value) and once you can access url_value with the expression language (via  ${url_value}) you can use all the available functions to manipulate expression language variables.   Here's an article with a couple of examples on UpdateRecord: https://community.cloudera.com/t5/Community-Articles/Update-the-Contents-of-FlowFile-by-using-UpdateRecord/ta-p/248267  (I noticed in the article they used some recordPath related functions like "replaceRegex", so I believe there might be a way to use these and then limit the entire issue to just one UpdateRecord processor! Sadly I'm not too familiar with these myself and this was the first time I've seen them)   And here's the expression language documentation: https://nifi.apache.org/docs/nifi-docs/html/expression-language-guide.html  You can see there are lots of useful functions to extract your api_value once you have ${url_value} as an attribute variable, for example "substring", "find"/"replace", "ifElse", etc. all of which you can try and use to ensure only the api_value is left in the end.   Hope this helps! I'm sure using ReplaceText and possibly JoltTransform could provide alternate solutions to the issue, however I believe UpdateRecord is the cleanest solution for this and truly makes use of the processor's abilities. If you struggle to use it correctly, you can reply with an example json and expected output and I'll try to write down the flow when I have time. ... View more