EXHIBIT 21.1

List of Subsidiaries of Upland Software, Inc. as of December 31, 2018

Upland Software, Inc./Logiciels Upland Inc.

Upland Software I, Inc.

Upland Software II, LLC

Upland Software IV, LLC

Upland Software V, Inc.

Upland Software VI, LLC

Upland Software VII, LLC

Upland IX, LLC

Ultriva, LLC

Advanced Processing & Imaging, Inc.

PowerSteering Software Limited

Omtool, Ltd.

RightAnswers, Inc.

Waterfall International, Inc.

Qvidian Corporation

InterFax Communications Limited

InterFax US Inc.

Return Fax 2000 Ltd

Data Guard Limited

References-Online, Inc. dba ROInnovation

Boulder Logic, LLC

Rapide Communication Ltd.

Rant & Rave Limited

Wire-E Limited

66099 Limited

Adestra, Inc.

Adestra Limited

Adestra Pty Limited