Definitive Healthcare Corp.

Evaluation of Disclosure Controls and Procedures

As of September 30, 2026, our management carried out an evaluation, under the supervision and participation of our Chief Executive Officer (principal executive officer) and our Chief Financial Officer (principal financial officer), of the effectiveness of the design of our disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934, as amended (“Exchange Act”)). Management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving its objectives, and management necessarily applies its judgment in evaluating the cost-benefit relationship of possible controls and procedures. Based on such evaluation, our Chief Executive Officer and Chief Financial Officer have concluded that our disclosure controls and procedures were effective as of September 30, 2026 to provide reasonable assurance that information to be disclosed by us in the reports that we file or submit under the Exchange Act is (i) recorded, processed, summarized, and reported within the time periods specified in the rules and forms of the SEC, and (ii) accumulated and communicated to management, including our principal executive and principal financial officers or persons performing similar functions, as appropriate to allow timely decisions regarding disclosure.

Changes in Internal Control Over Financial Reporting

There was no change in our internal control over financial reporting identified in connection with the evaluation required by Rule 13a-15(d) and 15d-15(d) of the Exchange Act that occurred during the fiscal quarter ended September 30, 2026 that has materially affected, or is reasonably likely to materially affect, our internal control over financial reporting.