If you need an open source budgeting software for your projects then Rapid Busines Information Organizer or Rabio could help you.
Best Open Source Budgeting Software
Rapid Business Information Organizer is an open-source budgeting software designed to organize projects and control their financial activities like budget, costs, earned value, forecast, projection, etc.
Take control of your budget using Rabio with the flexible Cost Breakdown Structure (CBS) of cost centers, cost categories, and the addition of tags.
Manage your Cost Control operations using Rabio data structure and flexible reporting system.
When it comes to data processing for project management, the flexible structure of Rabio can easily integrate with various data sources, manipulate data and produce accurate reports.
Rabio is open source and it is distributed for free under the GPLv3 license.
Check Rabio using the online demo, available 24/7.