I can help you with JSON, CSV, HTML kind of files processing and it can all happen on the client side not on the server, PDF might take some time and is a bit tricky but I think given the right amount of time and implementation it can be done, I have experience in text processing, especially if there's uniformity in the files and I can help you implement that in the client side using several technologies without buzzing the server with a whole lot of load, the code is going to run on the client's machine as well is not going to freeze it I'm going to use async processes which will make it happen like it's a request to the server but much faster and more reliable.