Webscorer PRO supports readers from the following vendors for passive & active chip timing:

Alien Technology - http://www.alientechnology.com
ACS - https://www.acs.com.hk
Emit - https://emit.no
Feibot - https://www.feibot.com
Impinj - http://www.impinj.com 
Motorola / Zebra - http://www.zebra.com 
Nordic ID - https://www.nordicid.com
MyLaps - https://www.mylaps.com
RaceResult - https://www.raceresult.com
RFID Timing Systems - https://rfidtiming.com
ThingMagic - http://www.thingmagic.com
Thinkify - https://thinkifyit.com

If you have a reader that's not listed above, you’ll want to check from the manufacturer’s specs that the specific model includes support for the LLRP (Low-Level Reader Protocol) which is how Webscorer PRO communicates with the RFID reader.  The LLRP protocol was invented in 2008, and adopted by the leading RFID vendors in the years following, so older RFID reader models may need a firmware upgrade to support it.  The support for Emit, Feibot, MyLaps, RaceResult, RFID Timing Systems and Thinkify readers is implemented with their respective (proprietary) protocols. 

Any handheld Bluetooth RFID reader that's capable of acting as an HID device (emulating a Bluetooth keyboard) can be used with Webscorer PRO.  ACS readers support NFC chip timing.

The active chip timing systems (wire loop antenna & chips with a battery) supported are Emit, Feibot, MyLaps and RaceResult.

Note that Webscorer PRO gets the chip data directly from the reader in real time - using a direct wire-level protocol to communicate with the reader.  This is in contrast to most "scoring software" that create results from raw chip data files generated by a separate "timing software" that feeds the files the scoring software in semi-real time during the race or after the race is over.  Hence Webscorer PRO can be thought of as a combined timing and scoring software which has the obvious benefits for getting real-time results, posted on a big screen or on a website while the race is underway via the "Live results" feature.   And allows the timing data to be monitored / corrected as it happens.