Exhibit 13.1

CERTIFICATION OF THE CHIEF EXECUTIVE OFFICER

PURSUANT TO 18 U.S.C. § 1350

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

I, Or Offer, Chief Executive Officer of Similarweb Ltd. (the “Company”), certify, pursuant to 18 U.S.C. § 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to my knowledge:

1 The Annual Report of the Company on Form 20-F for the fiscal year ended December 31, 2021 (the “Annual Report”) fully complies with the requirements of Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934; and

2 The information contained in the Annual Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Date: March 25, 2022

/s/ Or Offer

Or Offer

Chief Executive Officer

(Principal Executive Officer)

This certification accompanies the Report pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 and shall not, except to the extent required by such Act, be deemed filed by the Company for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”). Such certification will not be deemed to be incorporated by reference into any filing under the Securities Act of 1933, as amended, or the Exchange Act, except to the extent that the Company specifically incorporates it by reference.

A signed original of this written statement required by Section 906 has been provided to the Company and will be retained by the Company and furnished to the U.S. Securities and Exchange Commission or its staff upon request.