Sound Transit is leading the region’s effort to gather static (schedules, routes, fares, etc.) and dynamic (real-time and predictive location) transit data and make it accessible to developers and their applications. We work closely with our partner agencies to improve data quality and enhance the scope of what’s offered. More information is available at http://www.soundtransit.org/Open-Transit-Data
Several of the region's GTFS files are made available via download at: http://www.soundtransit.org/Developer-resources/Data-downloads
For access to services you will need an API key (see how to request a key above)
For data issues: you can post them here on github or send an email to Open_Transit_Data@soundtransit.org. When an issue comes in via email, it’s verified for specifications. If it can’t be addressed quickly it will be posted to the github issues list for the community’s benefit.