Document:

EX-10.1

 Exhibit 10.1 

THIS PROMISSORY NOTE (THIS “NOTE”) HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES
ACT”). THIS NOTE HAS BEEN ACQUIRED FOR INVESTMENT ONLY AND MAY NOT BE SOLD, TRANSFERRED OR ASSIGNED IN THE ABSENCE OF REGISTRATION OF THE RESALE THEREOF UNDER THE SECURITIES ACT OR AN OPINION OF COUNSEL REASONABLY SATISFACTORY IN FORM,
SCOPE AND SUBSTANCE TO BUILD ACQUISITION CORP. THAT SUCH REGISTRATION IS NOT REQUIRED. 
 PROMISSORY NOTE 

Principal Amount: Up to
$300,000                                        
                                         
                    Dated as of January 5, 2021 

FOR VALUE RECEIVED and subject to the terms and conditions set forth herein, Build Acquisition Corp., a Delaware corporation
(“Maker”), promises to pay to, or order to pay to, Build Acquisition Sponsor LLC, a Delaware limited liability company (“Payee”), the principal sum of Three Hundred Thousand Dollars ($300,000) or such lesser amount
as shall have been advanced by Payee to Maker and shall remain unpaid under this Note on the Maturity Date (as defined below) in lawful money of the United States of America, on the terms and conditions described below. All payments on this Note
shall be made by check or wire transfer of immediately available funds or as otherwise determined by Maker to such account as Payee may from time to time designate by written notice in accordance with the provisions of this Note. 

1. Principal. The entire unpaid principal balance of this Note shall be due and payable in full on the earlier of: (i) September 30,
2021, and (ii) the date on which Maker consummates an initial public offering of its securities (such earlier date of (i) and (ii), the “Maturity Date”), unless accelerated upon the occurrence of an Event of Default (as
defined below). The principal balance may be prepaid at any time by Maker, at its election and without penalty. Under no circumstances shall any individual, including but not limited to any officer, director, employee or shareholder of Maker, be
obligated personally for any obligations or liabilities of Maker hereunder. 
 2. Drawdown Requests. Maker and Payee agree that Maker may
request, from time to time, up to Three Hundred Thousand Dollars ($300,000) in draw downs under this Note to be used for costs and expenses related to Maker’s proposed initial public offering of its securities (the “IPO”),
including its formation. The principal of this Note may be drawn down from time to time prior to the Maturity Date upon request from Maker to Payee (each, a “Drawdown Request”). Each Drawdown Request must state the amount to be
drawn down, and must not be an amount less than Ten Thousand Dollars ($10,000) unless agreed upon by Maker and Payee. Payee shall fund each Drawdown Request no later than three (3) business days after receipt of a Drawdown Request;
provided, however, that the maximum principal amount of drawdowns outstanding under this Note at any time may not exceed Three Hundred Thousand Dollars ($300,000). No fees, payments or other amounts shall be due to Payee in connection
with, or as a result of, any Drawdown Request by Maker. 
 3. Interest. No interest shall accrue on the unpaid principal balance of this Note.

 4. Application of Payments. All payments shall be applied first to payment in full of any
costs incurred in the collection of any sum due under this Note, including (without limitation) reasonable attorney’s fees, then to the payment in full of any late charges and finally to the reduction of the unpaid principal balance of this
Note. 
 5. Events of Default. The following shall constitute an event of default (“Event of Default”): 

(a) Failure to Make Required Payments. Failure by Maker to pay the principal amount due pursuant to this Note on the Maturity Date. 

(b) Voluntary Bankruptcy, Etc. The commencement by Maker of a voluntary case under any applicable bankruptcy, insolvency,
reorganization, rehabilitation or other similar law, or the consent by it to the appointment of or taking possession by a receiver, liquidator, assignee, trustee, custodian, sequestrator (or other similar official) of Maker or for any substantial
part of its property, or the making by it of any assignment for the benefit of creditors, or the failure of Maker generally to pay its debts as such debts become due, or the taking of corporate action by Maker in furtherance of any of the foregoing.

 (c) Involuntary Bankruptcy, Etc. The entry of a decree or order for relief by a court having jurisdiction in the premises in
respect of Maker in an involuntary case under any applicable bankruptcy, insolvency or other similar law, or appointing a receiver, liquidator, assignee, custodian, trustee, sequestrator (or similar official) of Maker or for any substantial part of
its property, or ordering the winding-up or liquidation of its affairs, and the continuance of any such decree or order unstayed and in effect for a period of sixty (60) consecutive days. 

6. Remedies. 
 (a) Upon the
occurrence of an Event of Default specified in Section 5(a) hereof, Payee may, by written notice to Maker, declare this Note to be due immediately and payable, whereupon the unpaid principal amount of this Note, and all other amounts payable
thereunder, shall become immediately due and payable without presentment, demand, protest or other notice of any kind, all of which are hereby expressly waived, anything contained herein or in the documents evidencing the same to the contrary
notwithstanding. 
 (b) Upon the occurrence of an Event of Default specified in Sections 5(b) or 5(c), the unpaid principal balance of this
Note, and all other sums payable with regard to this Note, shall automatically and immediately become due and payable, in all cases without any action on the part of Payee. 

7. Waivers. Maker and all endorsers and guarantors of, and sureties for, this Note waive presentment for payment, demand, notice of dishonor,
protest, and notice of protest with regard to the Note, all errors, defects and imperfections in any proceedings instituted by Payee under the terms of this Note, and all benefits that might accrue to Maker by virtue of any present or future laws
exempting any property, real or personal, or any part of the proceeds arising from any sale of any such property, from attachment, levy or sale under execution, or providing for any stay of execution, exemption from civil process, or extension of
time for payment; and Maker agrees that any real estate that may be levied upon pursuant to a judgment obtained by virtue hereof, on any writ of execution issued hereon, may be sold upon any such writ in whole or in part in any order desired by
Payee. 

  
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 8. Unconditional Liability. Maker hereby waives all notices in connection with the delivery,
acceptance, performance, default, or enforcement of the payment of this Note, and agrees that its liability shall be unconditional, without regard to the liability of any other party, and shall not be affected in any manner by any indulgence,
extension of time, renewal, waiver or modification granted or consented to by Payee, and consents to any and all extensions of time, renewals, waivers, or modifications that may be granted by Payee with respect to the payment or other provisions of
this Note, and agrees that additional makers, endorsers, guarantors, or sureties may become parties hereto without notice to Maker or affecting Maker’s liability hereunder. 

9. Notices. All notices, statements or other documents which are required or contemplated by this Note shall be in writing and delivered
(i) personally or sent by first class registered or certified mail, overnight courier service to the address most recently provided to such party or such other address as may be designated in writing by the other party, (ii) by facsimile
to the number most recently provided to such party or fax number as may be designated in writing by the other party or (iii) by electronic mail (including .pdf), to the electronic mail address most recently provided to such party or such other
electronic mail address as may be designated in writing by the other party. Any notice or other communication so transmitted shall be deemed to have been given on the day of delivery, if delivered personally, on the business day following receipt of
written confirmation, if sent by facsimile or electronic mail, one (1) business day after delivery to an overnight courier service or five (5) days after mailing if sent by mail. 

10. Construction. THIS NOTE SHALL BE CONSTRUED AND ENFORCED IN ACCORDANCE WITH THE LAWS OF NEW YORK. 

11. Severability. Any provision contained in this Note which is prohibited or unenforceable in any jurisdiction shall, as to such jurisdiction,
be ineffective to the extent of such prohibition or unenforceability without invalidating the remaining provisions hereof, and any such prohibition or unenforceability in any jurisdiction shall not invalidate or render unenforceable such provision
in any other jurisdiction. 
 12. Trust Waiver. Notwithstanding anything herein to the contrary, Payee hereby waives any and all right, title,
interest or claim of any kind (“Claim”) in or to any distribution of or from the trust account to be established in which proceeds of the IPO (including the deferred underwriting discounts and commissions) and proceeds of the sale
of the warrants issued in a private placement to occur in connection with the IPO are to be deposited, as described in greater detail in the registration statement and prospectus to be filed with the Securities and Exchange Commission in connection
with the IPO, and hereby agrees not to seek recourse, reimbursement, payment or satisfaction for any Claim against the trust account for any reason whatsoever. 

13. Amendment; Waiver. Any amendment hereto or waiver of any provision hereof may be made with, and only with, the written consent of Maker and
Payee. 

  
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 14. Assignment. No assignment or transfer of this Note or any rights or obligations hereunder
may be made by any party hereto (by operation of law or otherwise) without the prior written consent of the other party hereto and any attempted assignment without the required consent shall be void. 

[Signature Page Follows] 

  
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 IN WITNESS WHEREOF, Maker, intending to be legally bound hereby, has caused this Note
to be duly executed by the undersigned as of the day and year first above written. 
  

			
	BUILD ACQUISITION CORP.
		
	By:	 	 /s/ Zeynep Young

		 	Name: Zeynep Young
		 	Title: Co-Chief Executive Officer

  

			
	Agreed and acknowledged:
	
	BUILD ACQUISITION SPONSOR LLC
		
	By:	 	 /s/ Lanham Napier

		 	Name: Lanham Napier
		 	Title: Authorized Signatory

 [Signature Page to Promissory Note]EX-10.2

 Exhibit 10.2 

LETTER AGREEMENT 

Dated [●], 2021 
 This letter agreement
(this “Letter Agreement”) is entered into by and among Build Acquisition Corp., a Delaware corporation (the “Company”), Build Acquisition Sponsor LLC, a Delaware limited liability company (the
“Sponsor”), and each other undersigned person (each such other undersigned person, an “Insider” and collectively, the “Insiders”). Reference is made to that certain underwriting
agreement (the “Underwriting Agreement”) entered into or proposed to be entered into by and among the Company, Cowen and Company, LLC and Allen & Company LLC, as representatives (the
“Representatives”) of the several underwriters (the “Underwriters”), relating to an underwritten initial public offering (the “Public Offering”), of up to 23,000,000 of the
Company’s units (including up to 3,000,000 units that may be purchased to cover the Underwriters’ option to purchase additional units, if any) (the “Units”), each comprised of one share of Class A common stock
of the Company, par value $0.0001 per share (“Class A Common Stock”), and one-third of one redeemable warrant (each whole warrant, a
“Warrant”). Each Warrant entitles the holder thereof to purchase one share of Class A Common Stock at a price of $11.50 per share, subject to certain adjustments. The Units shall be sold in the Public Offering pursuant
to a registration statement on Form S-1 and prospectus (the “Prospectus”) filed by the Company with the Securities and Exchange Commission (the “Commission”).
Certain capitalized terms used herein are defined in paragraph 12 hereof. 
 In order to induce the Company and the Underwriters to
enter into the Underwriting Agreement and to proceed with the Public Offering and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the Sponsor and the other Insiders each hereby agrees,
severally but not jointly, with the Company as follows: 
 1. The Sponsor and each Insider agrees that if the Company seeks stockholder
approval of a proposed Business Combination, then in connection with such proposed Business Combination, it, he or she shall (i) vote any Shares (as defined below) owned by it, him or her in favor of any proposed Business Combination (including
any proposals recommended by the Company’s board of directors in connection with such Business Combination) and (ii) not redeem any Shares owned by it, him or her in connection with such stockholder approval. 

2. The Sponsor and each Insider hereby agrees that in the event that the Company fails to consummate a Business Combination within 24 months
from the closing of the Public Offering, or such later period approved by the Company’s stockholders in accordance with the Company’s amended and restated certificate of incorporation, the Sponsor and each Insider shall take all reasonable
steps to cause the Company to (i) cease all operations except for the purpose of winding up, (ii) as promptly as reasonably possible but not more than ten (10) business days thereafter, subject to lawfully available funds therefor,
redeem 100% of the shares of Class A Common Stock sold as part of the Units in the Public Offering (the “Offering Shares”), at a per share price, payable in cash, equal to the aggregate amount then on deposit in the
Trust Account, including interest (which interest shall be net of taxes payable and less up to $100,000 of interest to pay dissolution expenses), divided by the number of then issued and outstanding Offering Shares, which redemption will completely
extinguish all Public Stockholders’ rights as stockholders (including the right to receive further liquidation distributions, if any) and (iii) as promptly as reasonably possible following such redemption, subject to the approval of the
Company’s remaining stockholders and the Company’s board of directors, dissolve and liquidate, subject in each case to the Company’s obligations under Delaware law to provide for claims of creditors and the requirements of other
applicable law. The Sponsor and each Insider agrees to not propose any amendment to the Company’s amended and restated certificate of incorporation (A) to modify the substance or timing of the Company’s obligation to allow redemption
in connection with the Company’s initial Business Combination or to redeem 100% of the Offering Shares if the Company does not complete its initial Business Combination within 24 months from the closing of the Public Offering or (B) with
respect to any other provision relating to stockholders’ rights or pre-initial Business Combination activity, unless the Company provides its Public Stockholders with the opportunity to redeem their
Offering Shares upon approval of any such amendment at a per share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest (which interest shall be net of taxes payable), divided by the number
of then issued and outstanding Offering Shares. 
 The Sponsor and each Insider acknowledges that it, he or she has no right, title,
interest or claim of any kind in or to any monies held in the Trust Account or any other asset of the Company as a result of any liquidation of the Company with respect to the Founder Shares held by it. The Sponsor and each Insider hereby further
waives, with respect to any Shares held by it, him or her, if any, any redemption rights it, he or 

  
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she may have in connection with (x) the consummation of a Business Combination, including, without limitation, any such rights available in the context of a stockholder vote to approve such
Business Combination or in the context of a tender offer made by the Company to purchase shares of Class A Common Stock and (y) a stockholder vote to approve an amendment to the Company’s amended and restated certificate of
incorporation (A) to modify the substance or timing of the Company’s obligation to allow redemption in connection with the Company’s initial Business Combination or to redeem 100% of the Offering Shares if the Company has not
consummated its initial Business Combination within 24 months from the closing of the Public Offering or (B) with respect to any other provision relating to stockholders’ rights or pre-initial
Business Combination activity (although the Sponsor and the Insiders shall be entitled to redemption and liquidation rights with respect to any Offering Shares it or they hold if the Company fails to consummate a Business Combination within 24
months from the date of the closing of the Public Offering). 
 3. Notwithstanding the provisions set forth in paragraphs 7(a) and
(b) below, during the period commencing on the effective date of the Underwriting Agreement and ending 180 days after such date, the Sponsor and each Insider shall not, without the prior written consent of the Representatives, (i) offer,
sell, contract to sell, pledge or otherwise dispose of, directly or indirectly, any Units, Warrants, Shares or any other securities convertible into, or exercisable, or exchangeable for, any shares of Class A Common Stock; provided,
however, that the Company may (1) issue and sell the Private Placement Warrants, (2) issue and sell the additional Units to cover the Underwriters’ over-allotment option, (3) register with the Commission pursuant to a
certain registration rights agreement to be entered into by and among the Company and certain holders party thereto and (4) issue securities in connection with the Company’s initial Business Combination; provided, further,
that the foregoing does not apply to the forfeiture by the Sponsor of any Founder Shares pursuant to their terms or any Transfer of Founder Shares to any current or future independent director of the company (as long as such current or future
independent director transferee is subject to this Letter Agreement or executes an agreement substantially identical to the terms of this Letter Agreement, as applicable to directors and officers at the time of such Transfer; and as long as, to the
extent any Section 16 reporting obligation is triggered as a result of such Transfer, any related Section 16 filing includes a practical explanation as to the nature of the Transfer). 

4. In the event of the liquidation of the Trust Account, the Sponsor (which for purposes of clarification shall not extend to any other
stockholders, members or managers of the Sponsor) agrees to indemnify and hold harmless the Company against any and all loss, liability, claim, damage and expense whatsoever (including, but not limited to, any and all legal or other expenses
reasonably incurred in investigating, preparing or defending against any litigation, whether pending or threatened, or any claim whatsoever) to which the Company may become subject as a result of any claim by (i) any third party (other than the
Company’s independent registered public accounting firm) for services rendered or products sold to the Company or (ii) a prospective target business with which the Company has discussed entering into a transaction agreement (a
“Target”); provided, however, that such indemnification of the Company by the Sponsor shall apply only to the extent necessary to ensure that such claims by a third party for services rendered (other
than the Company’s independent registered public accounting firm) or products sold to the Company or a Target do not reduce the amount of funds in the Trust Account to below (i) $10.00 per Offering Share or (ii) such lesser amount per
Offering Share held in the Trust Account as of the date of the liquidation of the Trust Account due to reductions in the value of the trust assets as of the date of the liquidation of the Trust Account, in each case, net of the amount of interest
which may be withdrawn to pay taxes, except as to any claims by a third party who executed a waiver of any and all rights to seek access to the Trust Account and except as to any claims under the Company’s indemnity of the Underwriters against
certain liabilities, including liabilities under the Securities Act of 1933, as amended. In the event that any such executed waiver is deemed to be unenforceable against such third party, the Sponsor shall not be responsible to the extent of any
liability for such third-party claims. The Sponsor shall have the right to defend against any such claim with counsel of its choice reasonably satisfactory to the Company if, within 15 days following written receipt of notice of the claim to the
Sponsor, the Sponsor notifies the Company in writing that it shall undertake such defense. 
 5. (a) To the extent that the Underwriters do
not exercise their option to purchase up to an additional 3,000,000 Units within 45 days from the date of the Prospectus (and as further described in the Prospectus), the Sponsor agrees that it shall forfeit, at no cost: a number of Founder Shares
in the aggregate equal to 750,000 multiplied by a fraction, (i) the numerator of which is 3,000,000 minus the number of Units purchased by the Underwriters upon the exercise of their option to purchase additional Units and (ii) the
denominator of which is 3,000,000. All references in this Letter Agreement to Founder Shares of the Company being forfeited shall take effect as a contribution of such Founder Shares, as applicable, to the Company’s capital as a matter of
Delaware law. The forfeiture will be adjusted to the extent that the option to purchase additional Units is not exercised in full by the Underwriters so that the number of Founder Shares will equal an aggregate of 20.0%, respectively, of the
Company’s issued and outstanding Shares immediately after the Public 

  
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Offering. The Initial Stockholders further agree that to the extent that the size of the Public Offering is increased or decreased, the Company will effect a stock dividend or stock repurchase or
redemption, as applicable, immediately prior to the consummation of the Public Offering in such amount as to maintain the number of Founder Shares at 20.0% of the Company’s issued and outstanding Shares upon the consummation of the Public
Offering. In connection with such increase or decrease in the size of the Public Offering, then (A) the references to 3,000,000 in the numerator and denominator of the formula in the first sentence of this paragraph shall be changed to a number
equal to 15.0% of the Units issued in the Public Offering and (B) the reference to 750,000 in the formula set forth in the first sentence of this paragraph shall be adjusted to, respectively, the total number of Founder Shares that the Sponsor
would have to return to the Company in order for the number of Founder Shares that the Sponsor owns (together with the Insiders) to equal an aggregate of 20.0% of the Company’s issued and outstanding Shares after the Public Offering. 

6. The Sponsor and each Insider hereby agrees and acknowledges that: (i) the Underwriters and the Company would be irreparably injured in
the event of a breach by such Sponsor or Insider of its, his or her obligations under paragraphs 1, 2, 3, 4, 5, 7(a), 7(b), and 10 of this Letter Agreement, (ii) monetary damages may not be an adequate remedy for such breach, and (iii) the
non-breaching party shall be entitled to seek injunctive relief, in addition to any other remedy that such party may have in law or in equity, in the event of such breach. 

7. (a) The Sponsor and each Insider agrees that it, he or she shall not Transfer any Founder Shares (or shares of Class A Common Stock
issuable upon conversion thereof) until the earlier of (A) one year after the completion of the Company’s initial Business Combination and (B) subsequent to the Business Combination, (x) the date on which the Company completes a
liquidation, merger, stock exchange, reorganization or other similar transaction that results in all of the Public Stockholders having the right to exchange their shares of Class A Common Stock for cash, securities or other property or
(y) if the last reported sale price of the Class A Common Stock equals or exceeds $12.00 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and other similar transactions) for any 20 trading days
within any 30-trading day period commencing at least 150 days after the Company’s initial Business Combination (the “Founder Shares Lock-Up
Period”). 
 (b) The Sponsor agrees that it shall not Transfer any Private Placement Warrants or any shares of Class A
Common Stock issued or issuable upon the exercise of the Private Placement Warrants, until 30 days after the completion of a Business Combination (the “Private Placement Warrants Lock-Up
Period”, collectively with the Founder Shares Lock-Up Period, the “Lock-Up Periods”). 

(c) Notwithstanding the provisions set forth in paragraphs 7(a) and (b), Transfers of the Founder Shares, Private Placement Warrants and shares
of Class A Common Stock issued or issuable upon the exercise or conversion of the Private Placement Warrants or the Founder Shares and that are held by the Sponsor or any Insider or any of their permitted transferees (that have complied with
this paragraph 7(c)), are permitted (a) to the Company’s directors or officers, any affiliates or family members of any of the Company’s directors or officers, any members of the Sponsor, or any affiliates of the Sponsor, (b) in
the case of an individual, by gift to a member of the individual’s immediate family or to a trust, the beneficiary of which is a member of the individual’s immediate family or an affiliate of such person, or to a charitable organization;
(c) in the case of an individual, by virtue of laws of descent and distribution upon death of the individual; (d) in the case of an individual, pursuant to a qualified domestic relations order; (e) by private sales or Transfers made
in connection with the consummation of the Company’s Business Combination at prices no greater than the price at which the securities were originally purchased; (f) in the event of the Company’s liquidation prior to the Company’s
completion of an initial Business Combination; (g) by virtue of the laws of Delaware or the Sponsor’s limited liability company agreement, as amended, upon dissolution of the Sponsor; or (h) in the event of the Company’s
completion of a liquidation, merger, stock exchange, reorganization or other similar transaction which results in all of the Public Stockholders having the right to exchange their shares of Class A Common Stock for cash, securities or other
property subsequent to the Company’s completion of an initial Business Combination; provided, however, that in the case of clauses (a) through (e), these permitted transferees must enter into a written agreement with the
Company agreeing to be bound by the Transfer restrictions and other applicable restrictions in this Letter Agreement. 
 8. The Sponsor and
each Insider represents and warrants that it, he or she has never been suspended or expelled from membership in any securities or commodities exchange or association or had a securities or commodities license or registration denied, suspended or
revoked. Each Insider’s biographical information furnished to the Company, if any (including any such information included in the Prospectus), is true and accurate in all respects and does not omit any material information with respect to such
Insider’s 

  
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background. The Sponsor and each Insider’s questionnaire furnished to the Company, if any, is true and accurate in all respects. The Sponsor and each Insider represents and warrants that: it
is not subject to or a respondent in any legal action for, any injunction, cease-and-desist order or order or stipulation to desist or refrain from any act or practice
relating to the offering of securities in any jurisdiction; it has never been convicted of, or pleaded guilty to, any crime (i) involving fraud, (ii) relating to any financial transaction or handling of funds of another person, or
(iii) pertaining to any dealings in any securities and it is not currently a defendant in any such criminal proceeding. 
 9. Except as
disclosed in, or as expressly contemplated by, the Prospectus, neither the Sponsor nor any Insider nor any affiliate of the Sponsor or any Insider, nor any director or officer of the Company, shall receive from the Company any finder’s fee,
reimbursement, consulting fee, monies in respect of any repayment of a loan or other compensation prior to, or in connection with any services rendered in order to effectuate the consummation of the Company’s initial Business Combination
(regardless of the type of transaction that it is). 
 10. The Sponsor and each Insider has full right and power, without violating any
agreement to which it is bound (including, without limitation, any non-competition or non-solicitation agreement with any employer or former employer), to enter into
this Letter Agreement and, as applicable, to serve as an officer and/or a director on the board of directors of the Company and hereby consents to being named in the Prospectus as an officer and/or a director of the Company. 

11. As used herein: 

“Business Combination” shall mean a merger, capital stock exchange, asset acquisition, stock purchase, reorganization
or similar business combination, involving the Company and one or more businesses; 
 “Founder Shares” shall mean the
5,750,000 shares of Class B common stock, par value $0.0001 per share, of the Company that are issued and outstanding immediately prior to the consummation of the Public Offering; 

“Initial Stockholders” shall mean the Sponsor and any Insider that holds Founder Shares; 

“Private Placement Warrants” shall mean the Warrants to purchase an aggregate of 4,000,000 shares of Class A
Common Stock of the Company (or up to 4,400,000 shares of Class A Common Stock depending on the extent to which the Underwriters’ over-allotment option is exercised pursuant to the Underwriting Agreement) that the Sponsor has agreed to
purchase for an aggregate purchase price of $6,000,000 in the aggregate (or up to $6,600,000 depending on the extent to which the Underwriters’ over-allotment option is exercised pursuant to the Underwriting Agreement), or $1.50 per Warrant, in
a private placement that shall occur substantially concurrently with the consummation of the Public Offering; 
 “Public
Stockholders” shall mean the holders of securities issued in the Public Offering; 
 “Shares” shall
mean, collectively, the shares of Class A Common Stock and the Founder Shares; 
 “Transfer” shall mean the
(a) sale or assignment of, offer to sell, contract or agreement to sell, hypothecate, pledge, grant of any option to purchase or otherwise dispose of or agreement to dispose of, directly or indirectly, or establishment or increase of a put
equivalent position or liquidation with respect to or decrease of a call equivalent position within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and the rules and
regulations of the Commission promulgated thereunder with respect to, any security, (b) entry into any swap or other arrangement that Transfers to another, in whole or in part, any of the economic consequences of ownership of any security,
whether any such transaction is to be settled by delivery of such securities, in cash or otherwise, or (c) public announcement of any intention to effect any transaction specified in clause (a) or (b) herein; and 

“Trust Account” shall mean the trust account into which the net proceeds of the Public Offering and a portion of the
proceeds from the sale of the Private Placement Warrants shall be deposited for the benefit of the Public Stockholders. 

  
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 12. This Letter Agreement constitutes the entire agreement and understanding of the parties
hereto in respect of the subject matter hereof and supersedes all prior understandings, agreements, or representations by or among the parties hereto, written or oral, to the extent they relate in any way to the subject matter hereof or the
transactions contemplated hereby. This Letter Agreement may not be changed, amended, modified or waived (other than to correct a typographical error) as to any particular provision, except by a written instrument executed by (1) each Insider
that is the subject of any such change, amendment modification or waiver and (2) the Sponsor. 
 13. No party hereto may assign either
this Letter Agreement or any of its rights, interests, or obligations hereunder without the prior written consent of the other parties. Any purported assignment in violation of this paragraph shall be void and ineffectual and shall not operate to
Transfer or assign any interest or title to the purported assignee. This Letter Agreement shall be binding on the Sponsor and each Insider and their respective successors, heirs and assigns and permitted transferees. 

14. This Letter Agreement shall be deemed severable, and the invalidity or unenforceability of any term or provision hereof shall not affect
the validity or enforceability of this Letter Agreement or of any other term or provision hereof. Furthermore, in lieu of any such invalid or unenforceable term or provision, the parties hereto intend that there shall be added as a part of this
Letter Agreement a provision as similar in terms to such invalid or unenforceable provision as may be possible and be valid and enforceable. 

15. This Letter Agreement shall be governed by and construed and enforced in accordance with the laws of the State of New York. The parties
hereto (i) all agree that any action, proceeding, claim or dispute arising out of, or relating in any way to, this Letter Agreement shall be brought and enforced in the courts of New York City, in the State of New York, and irrevocably submit
to such jurisdiction and venue, which jurisdiction and venue shall be exclusive and (ii) waive any objection to such exclusive jurisdiction and venue or that such courts represent an inconvenient forum. 

16. Any notice, consent or request to be given in connection with any of the terms or provisions of this Letter Agreement shall be in writing
and shall be sent by express mail or similar private courier service, by certified mail (return receipt requested), by hand delivery or facsimile or other electronic transmission. 

17. Each party hereto shall not be liable for any breaches or misrepresentations contained in this Letter Agreement by any other party to this
Letter Agreement (including, for the avoidance of doubt, any Insider with respect to any other Insider), and no party shall be liable or responsible for the obligations of another party, including, without limitation, indemnification obligations and
notice obligations. 
 18. This Letter Agreement shall terminate on the earlier of (i) the expiration of the Lock-Up Periods and (ii) the liquidation of the Company; provided, however, that this Letter Agreement shall earlier terminate in the event that the Public Offering is not consummated
and closed by June 30, 2021; provided further that paragraph 4 of this Letter Agreement shall survive such liquidation. 

19. This Letter Agreement may be executed in any number of original or facsimile counterparts and each of such counterparts shall for all
purposes be deemed to be an original, and all such counterparts shall together constitute but one and the same instrument. 
 [Signature page
follows] 

  
 5 

 
			
	Sincerely,
	
	BUILD ACQUISITION SPONSOR LLC
		
	By:	 	
                     
                                        

		 	Name: A. Lanham Napier
		 	Title:   Authorized Signatory

  

			
	Acknowledged and Agreed:
	
	BUILD ACQUISITION CORP.
		
	By:	 	
                     
                        

		 	Name: Zeynep Young
		 	Title:   Co-Chief Executive Officer

 [Signature Page to Letter Agreement] 

	
	Acknowledged and Agreed:
	
	A. LANHAM NAPIER,
	Director and Co-Chief Executive Officer of the Company
	
	  

	
	ZEYNEP YOUNG,
	Director and Co-Chief Executive Officer of the Company
	
	  

	
	TANNER CERAND,
	Chief Financial Officer and Chief Investment Officer of the Company
	
	  

	
	OWEN VAN NATTA,
	Director of the Company
	
	  

	
	NOAM OHANA,
	Director of the Company
	
	  

	
	                                      
    ,
	Director of the Company
	
	  

  
 [Signature Page to
Letter Agreement]

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