disaccent is a tool for converting diacritical marks (AKA accent marks) from plain text to the respective escaped LaTeX version.
It is written in Haskell and licensed under BSD 2-clause.
disaccent is a standard command-line tool that process the standard input stream (STDIN).
unicode2latex is an equivalent tool that I have written few years ago, in Python. It is functional and can be downloaded in its own repository.
Concerning the stability, it is more stable than disaccent, but I hope the situation will change very soon. 😄
In source-code readability, however, I think disaccent is much superior than unicode2latex, but that is a matter of taste (I think so). 😜