EXHIBIT 5.1

August 9, 2023

Flywire Corporation

141 Tremont St #10

Boston, MA 02111

Ladies and Gentlemen:

At your request, we have examined the automatically effective Registration Statement on Form S-3 filed by Flywire Corporation, a Delaware corporation (the “Company”) with the Securities and Exchange Commission (the “Commission”) on August 9, 2023 (the “Registration Statement”) in connection with the registration under the Securities Act of 1933, as amended (the “Securities Act”), of the offering and sale from time to time of (i) shares of the Company’s voting common stock, $0.0001 par value per share (the “Common Stock”), (ii) shares of the Company’s preferred stock, $0.0001 par value per share (the “Preferred Stock”), (iii) one or more series of debt securities (the “Debt Securities”) issuable pursuant to an indenture (the “Indenture”) by and between the Company and a financial institution to be identified therein as trustee (the “Trustee”), and/or (iv) warrants to purchase shares of Common Stock, Preferred Stock and/or Debt Securities (the “Warrants”). The Common Stock, the Preferred Stock, the Debt Securities and the Warrants are collectively referred to herein as the “Securities.” The Securities may be sold from time to time by the Company or selling securityholders to be named in a prospectus supplement as set forth in the Registration Statement, the prospectus contained within the Registration Statement (the “Prospectus”) and supplements to the Prospectus.

In connection with our opinion, we have examined such matters of fact as we have deemed necessary, which included examination of originals or copies of: the Company’s current Amended and Restated Certificate of Incorporation, as amended (the “Restated Certificate”), and the Company’s Amended and Restated Bylaws (the “Restated Bylaws”), the Registration Statement and the exhibits thereto; the Prospectus; certain corporate proceedings of the Company’s Board of Directors (the “Board”), the committee or the committees of the Board and the Company’s stockholders relating to adoption or approval of the Restated Certificate and Restated Bylaws, the filing of the Registration Statement and the registration of the Securities under the Securities Act and documents (including a report from the Company’s transfer agent) regarding the Company’s outstanding and reserved capital stock and other securities and such other documents as we have deemed advisable, and we have examined such questions of law as we have considered necessary.

In our examination of documents for purposes of this opinion, we have assumed, and express no opinion as to, the authenticity and completeness of all documents submitted to us as originals, the genuineness of signatures on documents reviewed by us, the conformity to originals and the completeness of all documents submitted to us as copies, the legal capacity of all parties executing any documents (other than the Company), the lack of any undisclosed termination or modification or waiver of any document, the absence of any extrinsic agreements or documents that might change or affect the interpretation or terms of documents, and the due authorization, execution and delivery of all documents by each party thereto other than the Company. In determining the good standing of the Company, we have relied solely upon a Certificate of Good Standing dated August 9, 2023 issued by the Delaware Secretary of State with respect to the Company, and a management certificate addressed to us and dated of even date herewith executed by the Company containing certain factual representations (the “Management Certificate”).

We also have assumed that any certificates or instruments representing the Securities will be, when issued, properly signed by authorized officers of the Company or their agents, and, in the case of Debt Securities, properly authenticated in accordance with the terms of the Indenture and delivered to the intended recipients with the intent that the Company be bound thereby. We also have assumed that the Indenture at the time of execution, authentication, issuance and delivery of the Debt Securities will be a valid and legally binding obligation of the Trustee.

As to matters of fact relevant to this opinion, we have relied solely upon our examination of the documents referred to above and the Management Certificate and have assumed the current accuracy and completeness of the information obtained from the documents referred to above and the representations and warranties made by representatives of the Company to us, including but not limited to those set forth in the Management Certificate. We have made no independent investigation or other attempt to verify the accuracy of any of such information or to determine the existence or non-existence of any other factual matters.

We render this opinion only with respect to, and express no opinion herein concerning the application or effect of the laws of any jurisdiction other than, (i) the existing federal laws of the United States of America, (ii) the Delaware General Corporation Law and reported judicial decisions relating thereto and (iii) solely with respect to whether or not the Debt Securities and Warrants are the valid and binding obligations of the Company, the existing laws of the state of New York.

In connection with our opinions expressed below, we have assumed that (i) at or prior to the time of the delivery of any of the Securities, there will not have occurred any change in the law or the facts affecting the validity or enforceability of the Securities, (ii) if any Debt Securities are issued, such Debt Securities will only be issued pursuant to the Indenture in the form filed with the Registration Statement as an exhibit, that there will not have occurred any change in law affecting the enforceability of the Debt Securities, and that the Indenture will be entered into in the state of New York, (iii) all applicable Company covenants restricting the issuance of Debt Securities will have been waived, (iv) if any Warrants are issued, such Warrants will be governed by the laws of the state of New York, that there will not have occurred any change in law affecting the enforceability of the Warrants, and that the Warrants will be entered into in the state of New York, (v) the Registration Statement and any amendments (including any necessary post-effective amendments) will have automatically become or been declared effective under the Securities Act and (vi) at the time of the offer, issuance and sale of any Securities, no stop order suspending the Registration Statement’s effectiveness will have been issued and remain in effect. We also have assumed that the terms of any Debt Securities to be established subsequent to the date hereof, the issuance and delivery of Securities subsequent to the date hereof and the compliance by the Company with the terms of such Securities will not violate any applicable law (including, without limitation, any law relating to usury) or result in a violation of any provision of any instrument or agreement then binding upon the Company or any restriction imposed by any court or governmental body having jurisdiction over the Company.

This opinion is qualified by, and is subject to, and we render no opinion with respect to, the following limitations and exceptions to the enforceability of the Debt Securities and the Warrants:

(1) The effect of the laws of bankruptcy, insolvency, reorganization, arrangement, moratorium, fraudulent conveyance, assignment for the benefit of creditors and other similar laws now or hereinafter in effect relating to or affecting the rights and remedies of creditors, including the effect of statutory or other laws regarding fraudulent transfers or preferential transfers.

(2) The effect of general principles of equity and similar principles, including, without limitation, concepts of materiality, reasonableness, good faith and fair dealing, public policy and unconscionability and the possible unavailability of specific performance, injunctive relief, or other equitable remedies, regardless of whether considered in a proceeding in equity or at law.

(3) In the case of the Debt Securities, the effect of laws relating to usury or permissible rates of interest for loans, forbearances or the use of money.

We express no opinion regarding the effectiveness of any waiver or stay, extension or usury laws, or of unknown future rights. Further, we express no opinion regarding the effect of provisions relating to indemnification, exculpation or contribution to the extent such provisions may be held unenforceable as contrary to federal or state securities laws.

The Company has informed us that the Company intends to issue, and/or selling securityholders to be named in a prospectus supplement intend to resell, the Securities from time to time on a delayed or continuous basis. This opinion is limited to the laws, including the rules and regulations, as in effect on the date hereof. We are basing this opinion on our understanding that, prior to issuing or reselling any Securities in connection with the Registration

Statement, the Company or selling securityholders will advise us in writing of the terms thereof and other information material thereto, will afford us an opportunity to review the operative documents pursuant to which such Securities are to be issued and/or resold (including the Registration Statement, the Prospectus and the applicable supplement to the Prospectus, as then in effect) and will file such supplement or amendment to this opinion (if any) as we may reasonably consider necessary or appropriate with respect to such Securities. However, we undertake no responsibility to monitor the Company’s future compliance with applicable laws, rules or regulations of the Commission or other governmental body. In particular, we assume that the Company will obtain the requisite approval of the Board and the requisite approval of its stockholders if required by the laws of the State of Delaware, or if necessary because the Company does not have a sufficient number of authorized but unissued and unreserved shares of capital stock at the time of issuance. We also assume the Company will timely file any and all supplements to the Registration Statement and Prospectus as are necessary to comply with applicable laws in effect from time to time and duly amend its Restated Certificate, as amended, to increase the authorized number of shares of its capital stock if the number of such shares to be sold pursuant to the Registration Statement would cause the Company to issue more shares than it has authorized.

Based upon the foregoing and subject to the qualifications and exceptions contained herein, we are of the following opinion:

1. With respect to the shares of Common Stock registered pursuant to the Registration Statement, when (i) the issuance of and the terms of the offering of the shares of Common Stock and related matters have been duly authorized by appropriate corporate action of the Board or a duly authorized committee thereof, and, if required, the stockholders of the Company and (ii) if required, certificates representing the shares of Common Stock have been duly executed, countersigned, registered and delivered either (a) in accordance with the applicable definitive purchase, underwriting or similar agreement approved by the Board, or upon the exercise of Warrants to purchase Common Stock, upon payment of the consideration therefor (not less than the par value of the Common Stock) provided for therein and approved by the Board or a duly authorized committee thereof, or (b) upon conversion or exercise of any other security of the Company, in accordance with the terms of such security or the instrument governing such security providing for such conversion or exercise as approved by the Board, for the consideration approved by the Board (in an amount not less than the par value per share of the Common Stock), then such shares of Common Stock will be validly issued, fully paid and nonassessable.

2. With respect to any particular series of shares of Preferred Stock registered pursuant to the Registration Statement, when (i) the issuance and terms of such shares of Preferred Stock, the terms of the offering thereof and related matters, including the adoption of a certificate of designation relating to such Preferred Stock conforming to the Restated Certificate, Restated Bylaws and the Delaware General Corporation Law (a “Certificate”) and the filing of the Certificate with the Delaware Secretary of State, have been duly authorized by appropriate corporate action of the Board and, if required, the stockholders of the Company and (ii) if required, certificates representing the shares of Preferred Stock have been duly executed, countersigned, registered and delivered either (a) in accordance with the applicable definitive purchase, underwriting or similar agreement approved by the Board, or upon the exercise of Warrants to purchase Preferred Stock, upon payment of the consideration therefor (in an amount not less than the par value per share of the Preferred Stock) provided for therein or (b) upon conversion or exercise of any other security of the Company, in accordance with the terms of such security or the instrument governing such security providing for such conversion or exercise as approved by the Board, for the consideration approved by the Board (in an amount not less than the par value per share of the Preferred Stock), then such shares of Preferred Stock will be validly issued, fully paid and nonassessable.

3. With respect to any Debt Securities registered pursuant to the Registration Statement, when (i) the issuance of such Debt Securities has been duly authorized by appropriate corporate action of the Board and, if required, the stockholders of the Company, (ii) an Indenture relating to such Debt Securities in the form filed with the Registration Statement as an exhibit has been duly authorized and validly executed and delivered by each of the Company (by duly authorized officers of the Company) and the Trustee, (iii) the form and terms of the Debt Securities have been duly established in accordance with the Indenture pursuant to resolutions duly adopted by the Board and as set forth in an officer’s certificate or supplemental indenture duly authorized by the Board and duly executed by an authorized officer of the Company and (iv) instruments representing such Debt Securities have been duly executed and authenticated in accordance with the terms of the Indenture and any supplement thereto, and issued, sold and delivered in the manner and for the consideration approved by the Board and stated in the

Registration Statement, the Prospectus and any prospectus supplement relating thereto (as amended as of the date of such issuance, sale and delivery) and any applicable definitive purchase, underwriting or similar agreement, or upon the exercise of Warrants to purchase Debt Securities, upon payment of the consideration therefor provided for therein, then the Debt Securities will be validly issued and will constitute valid and binding obligations of the Company enforceable against the Company in accordance with their terms.

4. With respect to any Warrants registered pursuant to the Registration Statement, when (i) the issuance and terms of such Warrants, the terms, execution and delivery of the warrant agreement relating to the Warrants (“Warrant Agreement”), the terms of the offering thereof and related matters have been duly authorized by appropriate corporate action of the Board and, if required, the stockholders of the Company, (ii) the Warrant Agreement has been duly authorized and validly executed and delivered by the Company by duly authorized officers of the Company, and (iii) such Warrants have been duly executed, issued and delivered by duly authorized officers of the Company in accordance with the provisions of the applicable Warrant Agreement and the applicable definitive purchase, underwriting or similar agreement approved by the Board, upon payment of the consideration therefor provided for therein and approved by the Board, such Warrants will constitute valid and binding obligations of the Company.

We consent to the use of this opinion as an exhibit to the Registration Statement and further consent to all references to us, if any, in the Registration Statement, the prospectus constituting a part thereof and any amendments thereto. In giving this consent we do not thereby admit that we come within the category of persons whose consent is required by the Securities Act or by the rules and regulations promulgated thereunder.

This opinion is intended solely for use in connection with the issuance and sale of the Securities subject to the Registration Statement and is not to be relied upon for any other purpose. In providing this letter, we are opining only as to the specific legal issues expressly set forth above, and no opinion shall be inferred as to any other matter or matters. This opinion is rendered on, and speaks only as of, the date of this letter first written above, is and based solely on our understanding of facts in existence as of such date after the aforementioned examination and does not address any potential changes in facts, circumstances or law that may occur after the date of this opinion letter. We assume no obligation to advise you of any fact, circumstance, event or change in the law or the facts that may hereafter be brought to our attention whether or not such occurrence would affect or modify any of the opinions expressed herein.

Very truly yours,

/s/ Gunderson Dettmer Stough Villeneuve

Franklin & Hachigian, LLP

GUNDERSON DETTMER STOUGH
VILLENEUVE FRANKLIN &

HACHIGIAN, LLP