Modify Post Data automatically (in Firefox?)

[Hypernia]

Hi,

I hope to post in the right section.

I am looking for an addon or something (in the best case for firefox) that lets me modify Postdata automatically. I already use Tamperdata but my problem is, that I have to modify Postdata automatically because of time limitations. An additional information: I have different dynamic parts in the Postdata and I just want to modify one of them.

Example:
1st Post: Postdata="ID=123 Value=LMB" should be modified to Postdata="ID=123 Value=ABC" and
2nd Post: Postdata="ID=456 Value=PIV" should be modified to Postdata="ID=456 Value=ABC".

I need this to be done automatically, as there is only a short timelimit until this ID gets invalid Oh and what is important too is that this tool should hopefully adjust the content lenght (what tamperdata does).

So if you know any tool for firefox or otherwise any other solution please let me know!

[pertti123]

I don't know if an add-on exists for this particular need, but a browser independent solution is to use an intercepting proxy, such as burp proxy.