This article examines the democratization of urban capital projects and its impact on public participation and sustainable development. In recent years, cities have faced challenges in financing and implementing infrastructure projects. One effective solution is to increase citizens' involvement in financing, decision-making, and executing urban projects. The Public-Private Partnership (PPP) model, which involves government collaboration with the private sector, offers benefits like reducing government expenditures, improving project quality, accelerating completion, and attracting foreign investment. However, challenges such as excessive dependence on private investors and potential corruption also exist. To address these issues, democratizing urban projects through active citizen participation is proposed. Crowdfunding, allowing citizens to contribute small investments to urban projects, has proven successful in countries like the U.S., Iceland, and France. This article is based on three theoretical frameworks: collaborative governance, social capital, and the sharing economy. In Iran, challenges like lack of transparency and unclear frameworks for crowdfunding hinder the effective implementation of this model. It is suggested to combine the PPP model with crowdfunding, create digital platforms for citizen participation, and offer financial incentives for small-scale investors. The conclusion emphasizes that democratizing urban projects is an innovative and effective approach for achieving sustainable urban development.