In Open Source Software (OSS), most of the contributions come from the user community than the project's core developers. Pull-based development model has become a recent trend in distributed projects development where contributions are submitted as pull requests. These pull requests are reviewed, and if accepted, merged into the project’s main repository. In this thesis, we perform two empirical studies which investigates pull request (PR) merges of Shopify projects available in its public repository, Active Merchant. In the quantitative study, we performed data mining on the repository to understand the types of merges followed by Shopify developers and different factors contributing to PR merge time and outcome. We performed a qualitative analysis of the results by performing a survey on the Shopify developers who contributed to Active Merchant. This helped in understanding developers’ perception of the factors affecting the time and outcome of PR merges.