This question is one of the hardest in web application development. And the reason for this is simple: applications are a solution to a unique challenge, which may require a particular methodology or a team of web app developers with specific expertise. It is easy to evaluate how much building the Twitter app costs, but building a new custom web app is a frontier that has not been explored yet. While web app development costs may vary, on average, a complete clone of a major social media app costs about $500K and takes nine months to assemble.
How Much Does It Cost to Develop a Web App?