I want to develop my own web-based tool for searching for messages in the inbox of my Gmail account and deleting some of them.
The projects that I've been working on in my programming life are very different from that one, so my question is: What languages, tools, and libraries should be used for this task?
Have you considered using gmail filters? There are some easy ways of doing this without resorting to writing full fledged programs see. This may not be as sophisticated as rolling up a custom program but it has served my needs pretty well so far. Also explore Gmail advanced search queries. Be forewarned a little ingenuity and creativity is required.
I think, you can use libgmail
The libgmail project is a pure Python binding to provide access to Google's Gmail web-mail service.
The library currently ships with a demonstration utility to archive messages from a Gmail account into mbox files, suitable for importing into a local email client.
Its free of cost.Download it here
Let me know whether it works for you or not.
You ought to be able to do it via a standard IMAP library, which should exist for every language.