The paper presents a flexible framework for the online evaluation of collaborative project-oriented e-learning platforms. The framework was developed for the evaluation of the COOPER platform [1], but it is flexible enough to be used for the evaluation of other collaborative platforms. The evaluation is based on questionnaires and on logs collected during the platform use. Here we focus on the questionnaire-based evaluation part, which was developed with the same WebRatio model-driven development tool that was used for the COOPER platform. This solution assures a uniform implementation and interface with the whole platform. Statistical analysis of the results is combined with other methods such as social networks evaluation (see [14] for details), thus offering a complex evaluation framework. Some evaluation results obtained in experiments developed in two use cases are presented along with conclusions derived from the experiments