UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

(Amendment No. _____)*

Similarweb LTD

(Name of Issuer)

Common Stock

(Title of Class of Securities)

M84137 10 4

(CUSIP Number)

Mr. Reich, 13th Floor, Building E, 89 Medinat Hayehudim Street,

Herzliya, Israel. +972-9-9703614

(Name, Address and Telephone Number of Person

Authorized to Receive Notices and Communications)

May 13, 2021

(Date of Event which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

☐ Rule 13d-1(b)

☐ Rule 13d-1(c)

☒ Rule 13d-1(d)

*    The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No. M84137 10 4  13G   Page 2 of 6 Pages

1	NAMES OF REPORTING PERSONS
	I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) ION Crossover Partners Ltd.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
	(a)☐
	(b)☒
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION
	Israel
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER
			5,772,183
		6	SHARED VOTING POWER
			0
		7	SOLE DISPOSITIVE POWER
			5,772,183
		8	SHARED DISPOSITIVE POWER
			0
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
	5,772,183
10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)
	☐
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)
	7.77%
12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)
	CO

CUSIP No. M84137 10 4  13G   Page 3 of 6 Pages

Item 1.

(a) Name of Issuer: SIMILARWEB LTD

(b) Address of Issuer’s Principal Executive Offices: 121 Menachem Begin RdTel Aviv-Yafo, 6701203 IsraelTel: +972-3-544-7882

Item 2.

(a) Name of Person Filing: This Schedule 13G is filed by the entity and persons listed below, all of whom together are referred to herein as the “Reporting Persons”: (i) ION Crossover Partners Ltd. (the “Management Company”), which serves as a management company and investment manager for investment entities. (ii) Gilad Shany, who serves as Director for the Management Company;

(b) Address of the Principal Office or, if none, residence: The principal business address of ION Crossover Partners Ltd.. is 13th Floor, Building E, 89 Medinat Hayehudim Street,.  The principal business address of Mr. Shany is 13th Floor, Building E, 89 Medinat Hayehudim Street, Herzliya, Israel.

(c) Citizenship: ION Crossover Partners Ltd. is organized under the laws of Israel.  Mr. Shany is a citizen of Israel.

(d) Title of Class of Securities: Common Stock

(e) CUSIP Number: M84137 10 4

CUSIP No. M84137 10 4  13G   Page 4 of 6 Pages

Item 3. If this statement is filed pursuant to §§240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

(a)           ☐ Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o).

(b)           ☐ Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c).

(c)           ☐ Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c).

(d)           ☐ Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8).

(e)           ☐ An investment adviser in accordance with §240.13d-1(b)(1)(ii)(E);

(f)           ☐ An employee benefit plan or endowment fund in accordance with §240.13d-1(b)(1)(ii)(F);

(g)           ☐ A parent holding company or control person in accordance with §240.13d-1(b)(1)(ii)(G);

(h)           ☐ A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);

(i)           ☐ A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);

(j)           ☐ Group, in accordance with §240.13d-1(b)(1)(ii)(J).

Item 4. Ownership.

Provide the following information regarding the aggregate number and percentage of the class of securities of the issuer identified in Item 1.

(a) Amount beneficially owned: As of May 13, 2021, the Reporting Persons beneficially own, in the aggregate, 5,772,183 shares of the Common Stock of the Issuer.

(b) Percent of class: 7.77%

(c) Number of shares as to which the person has:

(i) Sole power to vote or to direct the vote 5,772,183.

(ii) Shared power to vote or to direct the vote 0.

(iii) Sole power to dispose or to direct the disposition of 5,772,183.

(iv) Shared power to dispose or to direct the disposition of 0.

Instruction. For computations regarding securities which represent a right to acquire an underlying security see §240.13d-3(d)(1).

CUSIP No. M84137 10 4  13G   Page 5 of 6 Pages

Item 5. Ownership of Five Percent or Less of a Class.

If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following          ☐ .

Instruction. Dissolution of a group requires a response to this item.

Item 6. Ownership of More than Five Percent on Behalf of Another Person.

Item 7. Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company.

Item 8. Identification and Classification of Members of the Group.

Item 9. Notice of Dissolution of Group.

Item 10. Certification.

(a) The following certification shall be included if the statement is filed pursuant to §240.13d-1(b):
By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

(b) The following certification shall be included if the statement is filed pursuant to §240.13d-1(c):
By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

CUSIP No. M84137 10 4  13G   Page 6 of 6 Pages

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

 May 13, 2021

 Date

 /s/Gilad Shany

 Signature

 Director

 Name/Title