Exhibit A

JOINT FILING AGREEMENT

The undersigned agree that this Schedule 13G dated August 13, 2025 relating to the Common Stock, $0.001 par value per share, of Integral Ad Science Holding Corp. shall be filed on behalf of the undersigned.

SUNRIVER MANAGEMENT LLC

By: /s/ Randolph Willett Cook

Name: Randolph Willett Cook

Title: Managing Member

RANDOLPH WILLETT COOK

By: /s/ Randolph Willett Cook