Exhibit 24

                               POWER OF ATTORNEY
                         For Executing Forms 3, 4 and 5

KNOW ALL BY THESE PRESENTS, that the undersigned hereby constitutes and appoints
each of Reid Hoffman, Mark Pincus, Michael Thompson, David Cohen and Reinvent
Sponsor Y LLC, or any of them, each acting alone, his or her true and lawful
attorney-in-fact to:

      (1) execute for and on behalf of the undersigned a Form 3, Form 4 or Form
          5, or any amendment thereto, relating to the securities of Reinvent
          Technology Partners Y, in accordance with Section 16(a) of the
          Securities Exchange Act of 1934 and the rules thereunder;

      (2) do and perform any and all acts for and on behalf of the undersigned
          which may be necessary or desirable to complete and execute such Form
          3, Form 4 or Form 5, or any amendment thereto, and the timely filing
          of such form with the United States Securities and Exchange Commission
          and any other authority; and

      (3) take any other action of any type whatsoever in connection with the
          foregoing which, in the opinion of such attorney-in-fact, may be of
          benefit to, in the best interest of, or legally required by, the
          undersigned, it being understood that the documents executed by such
          attorney-in-fact on behalf of the undersigned pursuant to this Power
          of Attorney shall be in such form and shall contain such terms and
          conditions as such attorney-in-fact may approve in such attorney-in-
          fact's discretion.

The undersigned hereby grants to each such attorney-in-fact full power and
authority to do and perform any and every act and thing whatsoever requisite,
necessary and proper to be done in the exercise of any of the rights and powers
herein granted, as fully to all intents and purposes as such undersigned might
or could do if personally present, hereby ratifying and confirming all that such
attorney-in-fact shall lawfully do or cause to be done by virtue of this Power
of Attorney and the rights and powers herein granted.  The undersigned
acknowledges that each of the foregoing attorneys-in-fact, in serving in such
capacity at the request of the undersigned, is not assuming any of the
undersigned's responsibilities to comply with Section 16 of the Securities
Exchange Act of 1934.  This Power of Attorney shall remain in full force and
effect until the undersigned is no longer required to file Forms 3, 4 and 5 with
respect to the undersigned's holdings of and transactions in securities issued
by Reinvent Technology Partners Y unless earlier revoked by the undersigned in a
signed writing delivered to the foregoing attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 15th day of March, 2021.

                                    By: /s/ Colleen McCreary
                                        Colleen McCreary