Weblate is an open source web based localization system. The software also can be self-hosted.
Malayalam Projects on Weblate: Malayalam @ Hosted Weblate
Everyone can view and suggest translations on Weblate without having an account.
An account is required for saving the changes.
To create an account, go to https://hosted.weblate.org/accounts/register/ and enter the credentials or sign in using Github, Gitlab, etc.
For more information, please read the Weblate Documentation