There is a web-based version of Oncotator which you can use for annotation without running anything on your own machine.
However, please note that the web-based version is an older version, with fewer datasources and many limitations. We urge you to use the downloadable version instead, and at this time we do not provide user support for the web-based version. It is simply provided as-is.
Note also that on rare occasions the server malfunctions and needs to be rebooted. If you experience any server errors (e.g. an error message stating that the server is unavailable), please post a note in the thread below and we'll reboot it as soon as we can.