I took the liberty to modify OP's input slightly, because as it stands , it's not properly structured json data (due to the {...} part) and implemented a small python script that works with multiple dictionaries, assuming that we're dealing with a dictionary per line. Additionally, as has been discussed in the comments to the question, OP also wanted to remove http:// part.
The script below implements everything discussed above.
#!/usr/bin/env python
import json,sys
with open(sys.argv[1]) as f:
for line in f:
data=json.loads(line)
if data["url"][-1] == '/':
data["url"]=data["url"][:-1].replace('http://','')
if data["originalUrl"][-1] == '/':
data["originalUrl"]=data["originalUrl"][:-1].replace('http://','')
json.dump(data,sys.stdout)
print("")
Test run:
$ cat input.txt
{"url":"http://example.com/vary/file/","originalUrl":"http://example.com/vary/file/","applications":[{"somedata": "blah"}]}
{"url":"http://another-example.com/vary/file/","originalUrl":"http://example.com/vary/file/","applications":[{"somedata": "blah"}]}
$ ./remove_slash.py input.txt
{"url": "example.com/vary/file", "applications": [{"somedata": "blah"}], "originalUrl": "example.com/vary/file"}
{"url": "another-example.com/vary/file", "applications": [{"somedata": "blah"}], "originalUrl": "example.com/vary/file"}