Exhibit 10.16

AMENDMENT TO EXECUTIVE SEVERANCE
AND CHANGE IN CONTROL LETTER AGREEMENT

Dear Mark:

This Amendment to Executive Severance and Change in Control Letter Agreement
(the “Amendment”) to is made and entered into effective as of December 31, 2018
(the “Amendment Effective Date”) by and between ChannelAdvisor Corporation
(“ChannelAdvisor”) and Mark E. Cook (“You”). This Agreement amends the Executive
Severance and Change in Control Letter Agreement between You and ChannelAdvisor
dated August 31, 2015 (the “Agreement”) effective as of the Amendment Effective
Date. Except as expressly provided in this Amendment, the Agreement, as amended
by this Amendment, remains in full force and effect. All capitalized terms not
defined in this Amendment have the meaning stated in the Agreement.

Section 3 of the Agreement is hereby amended and restated to read as follows:

“3.    Change in Control with No Termination
If there is a Change in Control and Your employment has not been terminated for
any reason as of the first anniversary of the Change in Control, then You shall
receive one (1) year of acceleration of vesting of all Your Awards that were
granted before the Amendment Effective Date and are unvested as of the first
anniversary of the Change in Control, with the additional vesting being credited
on the first anniversary of the Change in Control.”

Sincerely,
CHANNELADVISOR CORPORATION
/s/ David J. Spitz    
David J. Spitz
Chief Executive Officer
Accepted and agreed to by:

/s/ Mark E. Cook    
Mark E. Cook