  Data annotation is an important and necessary task for all NLP applications.
Designing and implementing a web-based application that enables many annotators
to annotate and enter their input into one central database is not a trivial
task. These kinds of web-based applications require a consistent and robust
backup for the underlying database and support to enhance the efficiency and
speed of the annotation. Also, they need to ensure that the annotations are
stored with a minimal amount of redundancy in order to take advantage of the
available resources(e.g, storage space). In this paper, we introduce WASA, a
web-based annotation system for managing large-scale multilingual Code
Switching (CS) data annotation. Although WASA has the ability to perform the
annotation for any token sequence with arbitrary tag sets, we will focus on how
WASA is used for CS annotation. The system supports concurrent annotation,
handles multiple encodings, allows for several levels of management control,
and enables quality control measures while seamlessly reporting annotation
statistics from various perspectives and at different levels of granularity.
Moreover, the system is integrated with a robust language specific date
prepossessing tool to enhance the speed and efficiency of the annotation. We
describe the annotation and the administration interfaces as well as the
backend engine.
