X0508 4 2026-02-17 0 0001562088 Duolingo, Inc. DUOL 0001869758 Chen Stephen C. C/O DUOLINGO, INC. 5900 PENN AVENUE PITTSBURGH PA 15206 0 1 0 0 General Counsel 1 Class A Common Stock 2026-02-17 4 S 0 896 110.06 D 32446 D Class A Common Stock 2026-02-18 4 S 0 821 111.83 D 31625 D Class A Common Stock 2026-02-18 4 S 0 480 113.9504 D 31145 D Class A Common Stock 2026-02-18 4 S 0 520 114.5519 D 30625 D Class A Common Stock 2026-02-18 4 S 0 80 115.47 D 30545 D Represents shares automatically sold to satisfy tax withholding obligations in connection with the vesting of Restricted Stock Units ("RSUs") and delivery of shares. The sale was effected pursuant to the Reporting Person's Rule 10b5-1 trading plan adopted on May 27, 2025. The price reported in Column 4 is a weighted average sale price calculated by the broker executing the sales. These shares were sold in multiple transactions at prices ranging from $111.83 to $112.79, inclusive. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote. The price reported in Column 4 is a weighted average sale price calculated by the broker executing the sales. These shares were sold in multiple transactions at prices ranging from $113.31 to $114.23, inclusive. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote. The price reported in Column 4 is a weighted average sale price calculated by the broker executing the sales. These shares were sold in multiple transactions at prices ranging from $114.31 to $115.23, inclusive. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote. The price reported in Column 4 is a weighted average sale price calculated by the broker executing the sales. These shares were sold in multiple transactions at prices ranging from $115.47 to $115.52, inclusive. The Reporting Person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote. /s/ Stephen C. Chen 2026-02-19