UNITED STATES
 SECURITIES AND EXCHANGE COMMISSION
 Washington, D.C. 20549
 __________________________________
 FORM 10-K/A
 (Amendment No. 1)
 __________________________________
 (Mark One)

 x
 ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

 For the fiscal year ended December 31, 2023
 OR

 o
 TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

 For the transition period from _____to _____
 Commission File Number: 001-39799
 __________________________________
 Certara, Inc.
 (Exact Name of Registrant as Specified in Its Charter)
 __________________________________

 Delaware
 82-2180925

 (State or other jurisdiction of incorporation or organization)
 (I.R.S. Employer Identification No.)

 4 Radnor Corporate Center, Suite 350
 Radnor, Pennsylvania

 19087

 (Address of principal executive offices)
 (Zip Code)

 Registrant's telephone number, including area code: ( 415) 237-8272
 Securities registered pursuant to Section 12(b) of the Act:

 Title of each class
 Trading Symbol
 Name of each exchange
on which registered

 Common stock, par value $0.01 per share
 CERT
 The Nasdaq Stock Market LLC

 Securities registered pursuant to Section 12(g) of the Act: None
 Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.
 Yes o No x
 Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.
 Yes o No x
 Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes x No o
 Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes x No o
 Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of "large accelerated filer," "accelerated filer," "smaller reporting company," and "emerging growth company" in Rule 12b-2 of the Exchange Act.

 Large accelerated filer x

 Accelerated filer o

 Non-accelerated filer o

 Smaller reporting company o

 Emerging growth company o

 If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. o
 Indicate by check mark whether the registrant has filed a report on and attestation to its management's assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. x
 If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements. o
 Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant's executive officers during the relevant recovery period pursuant to §240.10D-1(b). o
 Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes o No x
 The aggregate market value of the registrant's outstanding voting common stock held by non-affiliates on June 30, 2023, determined using the per share closing price on that date on The Nasdaq Global Select Market, was $ 2.2 billion. There is no non-voting common equity of the registrant outstanding. Shares held by each executive officer and director and by each other person or entity deemed to be an affiliate have been excluded in such calculation. The determination of affiliate status is not necessarily a conclusive determination for other purposes.
 As of December 10, 2024, the registrant had 160,987,731 shares of common stock, par value $0.01 per share, outstanding.
 DOCUMENTS INCORPORATED BY REFERENCE

 Part III of this Form 10-K incorporates information by reference from the registrant's definitive proxy statement that was filed with the Securities and Exchange Commission within 120 days after the close of the fiscal year covered by this report..

 EXPLANATORY NOTE
 Certara, Inc. (the "Company") is filing this Amendment No. 1 (this "Amendment") on Form 10-K/A to amend its Annual Report on Form 10-K for the fiscal year ended December 31, 2023, filed with the Securities and Exchange Commission on February 29, 2024 (the "Original 10-K") for the purpose of amending and restating Part II, Item 9A in its entirety to explicitly state management's conclusion that internal control over financial reporting was effective as of December 31, 2023 pursuant to Item 308(a)(3) of Regulation S-K. In addition, the Company's Chief Executive Officer and Chief Financial Officer have provided new certifications dated as of the date of this Amendment. Except as expressly described herein, no other changes have been made to the Original 10-K. This Amendment speaks as of the date of the Original 10-K and does not reflect events that may have occurred after the date of the Original 10-K or modify or update any disclosures that may have been affected by subsequent events.

 Item 9A. Controls and Procedures.
 Evaluation of Disclosure Controls and Procedures
 As of the end of the period covered by this Annual Report on Form 10-K, we performed an evaluation under the supervision and with the participation of management, including our Chief Executive Officer and our Chief Financial Officer, of the design and effectiveness of our disclosure controls and procedures (as defined in Rules 13a-15(e) or 15d-15(e) under the Securities Exchange Act of 1934 as amended (the "Exchange Act")). Based upon that evaluation, our Chief Executive Officer and Chief Financial Officer concluded, as of the end of the period covered by this Annual Report that our disclosure controls and procedures were effective at the reasonable assurance level to ensure that information required to be disclosed was recorded, processed, summarized and reported within the time periods specified in the SEC's rules and forms, and to provide reasonable assurance that information required to be disclosed in such reports is accumulated and communicated to the Company's management, including its Chief Executive Officer and Chief Financial Officer, as appropriate to allow timely decisions regarding required disclosure.
 Management's Annual Report on Internal Control over Financial Reporting
 Our management is responsible for establishing and maintaining adequate internal control over financial reporting, as is defined in the Exchange Act. Internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of our financial reporting and the preparation of financial statements for external reporting

 purposes in accordance with GAAP and includes those policies and procedures that: (1) pertain to the maintenance of records that in reasonable detail accurately and fairly reflect our transactions and the dispositions of our assets (2) provide reasonable assurance that our transactions are recorded as necessary to permit preparation of financial statements in accordance with GAAP and that our receipts and expenditures are being made only in accordance with appropriate authorizations and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use or disposition of our assets that could have a material effect on our consolidated financial statements.

 Our management conducted an evaluation of the effectiveness of our internal control over financial reporting as of December 31, 2023, based on the framework in Internal Control – Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission. Based on this evaluation, management concluded that, as of December 31, 2023, our internal control over financial reporting was effective.
 RSM US LLP, the independent registered public accounting firm that audited our consolidated financial statements as of and for the year ended December 31, 2023 included in this Report, has also audited the effectiveness of Certara's internal control over financial reporting as of December 31, 2023. The report of RSM US LLP is included under Item 8 of this Report.
 Changes in Internal Control over Financial Reporting
 There were no changes in our internal control over financial reporting (as such term is defined in Rules 13a-15(f) under the Exchange Act) during the quarter ended December 31, 2023 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

 Item 15. Exhibits, Financial Statement Schedules.

 (a)The following exhibits as required by Item 601 of Regulation S-K are filed as part of this Amendment:

 Incorporated by Reference

 Exhibit Number
 Exhibit Title
 Form
 File No.
 Exhibit
 Filing Date

 2.1
 Agreement and Plan of Merger dated as of August 2, 2021, by and among Certara, Inc., Puma Merger Sub, LLC and Shareholder Representative Services LLC, as the Equityholder Representative thereunder

 2.1
 8/5/2021

 3.1
 Amended and Restated Certificate of Incorporation of Certara, Inc.

 S-8
 333-251368
 4.1
 12/15/2020

 3.2
 Amended and Restated Bylaws of Certara, Inc.

 S-8
 333-251368
 4.2
 12/15/2020

 4.1
 Form of Stock Certificate for Common Stock

 S-1/A
 4.1
 12/03/2020

 4.2
 Description of Certara, Inc.'s Securities

 4.2

 10.1
 Credit Agreement, dated as of August 15, 2017, among Certara Holdings, Inc. (f/k/a EQT Avatar Holdings, Inc.), Certara Holdco, Inc., Certara USA, Inc., EQT Avatar Intermediate, Inc., Jefferies Finance LLC, as Administrative Agent and Issuing Bank, Golub Capital LLC as Issuing Bank and each lender from time to time party thereto

 S-1/A
 10.3

 10.2
 First Amendment, dated as of January 24, 2018, to the Credit Agreement, among Certara Holdings, Inc. (f/k/a EQT Avatar Holdings, Inc.), Certara Holdco, Inc., Certara USA, Inc., EQT Avatar Intermediate, Inc., Jefferies Finance LLC, as Administrative Agent and Issuing Bank, Golub Capital LLC as Issuing Bank and each lender from time to time party thereto

 S-1/A
 10.4

 10.3
 Second Amendment, dated as of April 3, 2018, to the Credit Agreement, among Certara Holdings, Inc. (f/k/a EQT Avatar Holdings, Inc.), Certara Holdco, Inc., Certara USA, Inc., Certara Intermediate, Inc. (f/k/a EQT Avatar Intermediate, Inc.), Jefferies Finance LLC, as Administrative Agent and Issuing Bank, Golub Capital LLC as Issuing Bank and each lender from time to time party thereto

 S-1/A
 10.5

 10.4
 Third Amendment, dated as of June 17, 2021, to the Credit Agreement, among Certara Holdings, Inc., Certara Holdco, Inc., Certara USA, Inc., Certara Intermediate, Inc., Bank of America, N.A., as Administrative Agent for the lenders from time to time party thereto and collateral agent for the secured parties thereunder

 10.1
 6/22/2021

 10.5
 Loan Guaranty, dated as of August 15, 2017, by and among the Loan Guarantors, as defined therein, and Jefferies Finance LLC, as Administrative Agent

 S-1/A
 10.6

 10.6
 Pledge and Security Agreement, dated as of August 15, 2017, by and among the Grantors, as defined therein, and Jefferies Finance LLC, as Agent

 S-1/A
 10.7

 10.7
 Loan Agreement, dated as of July 6, 2017, between Santo Holding (Deutschland) GmbH and Certara, Inc. (f/k/a EQT Avatar Topco, Inc.)

 S-1/A
 10.8

 10.8*
 Form of Indemnification Agreement between Certara, Inc. and directors and executive officers of Certara, Inc.

 S-1/A
 10.9
 11/25/2020

 10.9*
 Employment Agreement, dated as of May 14, 2019, by and among EQT Avatar Parent L.P., Certara USA, Inc. and William Feehery

 S-1/A
 10.10

 10.10*
 Employment Agreement, dated September 26, 2018 between Certara UK Limited and Robert Aspbury

 10.21
 3/1/2022

 10.11*
 Employment Agreement, dated as of July 20, 2020, between Certara USA, Inc. and Leif E. Pedersen

 10.12

 10.12*
 Employment Agreement Dated as of July 11, 2014, between Certara USA, Inc. and M. Andrew Schmick.*

 10.11

 10.13*
 Employment Agreement, dated as of September 2, 2016, between D3 MEDICINE LLC, Certara USA, Inc. and Patrick Smith

 10.12
 3/1/2023

 10.14*
 Amended and Restated Employment Agreement dated as of November 7, 2023 between the Company and John E. Gallagher.*

 10.1
 11/08/2023

 10.15
 Form of Exchange Acknowledgement and Agreement

 S-1/A
 10.19
 12/03/2020

 10.16
 Form of Stock Restriction Agreement*

 S-1/A
 10.20
 12/03/2020

 10.17
 Form of Restricted Stock Unit Grant and Award Agreement (Certara, Inc. 2020 Incentive Plan)

 10.14

 10.18
 Certara, Inc. 2020 Incentive Plan

 S-1/A
 10.18
 11/25/2020

 10.19
 Form of 2022 Performance Stock Unit Grant Notice and Agreement for Certara, Inc. 2020 Incentive Plan

 10.1
 5/7/2021

 10.20
 2022 Amended and Restated Form of PSU Grant Award Agreement**

 10.2
 5/8/2023

 10.21
 Form of PSU Grant and Award Agreement (2023 Grants) **

 10.3
 5/8/2023

 10.22
 Certara, Inc. 2020 Employee Stock Purchase Plan

 S-1/A
 10.21
 11/25/2020

 10.23
 Certara, Inc. Directors Deferral Plan*

 10.18

 10.24
 Letter Agreement Dated as of November 3, 2022, by and among Certara, Inc. and Arsenal Saturn Holdings LP.

 10.1
 11/7/2022

 10.25
 Stockholders Agreement, dated as of November 3, 2022, by and among Certara, Inc. and the other parties thereto

 10.2
 11/7/2022

 10.26
 Registration Rights Agreement, dated as of November 3, 2022, by and among Certara, Inc. and the other parties thereto

 10.3
 11/7/2022

 10.27
 LIBOR Transition Amendment.

 10.1
 8/9/2023

 10.28#
 Clawback Policy Effective December 1, 2023*

 16.1
 Letter from CohnReznick LLP to the Securities and Exchange Commission, dated March 30, 2022

 16.1
 3/30/2022

 21.1#
 Subsidiaries of the Registrant

 23.1#
 Consent of CohnReznick LLP

 23.2#
 Consent of RSM US LLP

 24.1#
 Power of Attorney (included in the signature page to this Annual Report)

 31.1^
 Certification of Principal Executive Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002

 31.2^
 Certification of Principal Financial and Accounting Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002

 32.1^
 Certification of Principal Executive Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002+

 32.2^
 Certification of Principal Financial Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002+

 101.INS

 101.SCH

 101.CAL

 101.DEF

 101.LAB

 101.PRE

 * Management contract or compensatory plan or arrangement.

 ** Certain schedules and exhibits have been omitted pursuant to Item 601(a)(5) of Regulation S-K. The registrant agrees to furnish a copy of any omitted schedule or exhibit to the SEC upon request; provided, however, that the registrant may request confidential treatment pursuant to Rule 24b-2 of the Exchange Act for any document so furnished.

 # Previously filed with the Original 10-K.

 ^ Filed herewith.

 + This certification is deemed not filed for purposes of Section 18 of the Exchange Act, or otherwise subject to the liability of that section, nor shall it be deemed incorporated by reference into any filing under the Securities Act or the Exchange Act.

 Signatures
 Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this Form 10-K/A to be signed on its behalf by the undersigned, thereunto duly authorized.

 CERTARA, INC.

 Date: December 16, 2024

 By:
 /s/ WILLIAM F. FEEHERY

 Name:
 William F. Feehery

 Title:
 Chief Executive Officer
(Principal Executive Officer)