Duolingo, Inc.

(a) None.

(b) Trading Plans

On September 12, 2025, each of Dr. Severin Hacker, Chief Technology Officer and member of the Company’s Board of Directors, the SBH Trust dated March 10, 2020 (“SBH Trust”) and the Severin Hacker Foundation, entered into a joint 10b5-1 sales plan (the “Hacker 10b5-1 Sales Plan”). The Hacker 10b5-1 Sales Plan, which is intended to satisfy the affirmative defense of Rule 10b5-1(c) under the Exchange Act, will commence trading once Dr. Hacker’s 10b5-1 sales plan dated September 11, 2024 ends. Under the Hacker 10b5-1 Sales Plan, a maximum aggregate of up to 515,000 shares of the Company’s Class A common stock may be sold, consisting of (i) the net number of shares of Class A common stock issuable upon the exercise of 50,000 vested stock options held by Dr. Severin Hacker that remain unsold pursuant to Mr. Hacker’s 10b5-1 sales plan dated September 11, 2024 (which net amount is not currently determinable), (ii) up to 465,000 shares held by SBH Trust, and (iii) up to 50,000 shares held by the Severin Hacker Foundation). The Hacker 10b5-1 Sales Plan will remain in effect until the earlier of (1)December 31, 2027, (2) the date on which all trades set forth in the Hacker 10b5-1 Sales Plan have been executed, or (3) such time as the Hacker 10b5-1 Sales Plan is otherwise terminated or expires according to its terms.

On September 15, 2025, Natalie Glance, Chief Engineering Officer, entered into a 10b5-1 sales plan (the “Glance 10b5-1 Sales Plan”) intended to satisfy the affirmative defense of Rule 10b5-1(c) of the Exchange Act and providing for (i) exercise of vested stock options and the associated sale of up to 14,759 shares of the Company’s Class A common stock, (ii) the sale of 3,285 shares of Class A common stock, and (iii) the net number of shares of Class A common stock underlying 16,723 unvested restricted stock units after giving effect to the number of shares to be sold outside of the Glance 10b5-1 Plan to satisfy tax withholding obligations (which net amount is not currently determinable). The Glance 10b5-1 Sales Plan will remain in effect until the earlier of (1)December 31, 2026, (2) the date on which all trades set forth in the Glance 10b5-1 Sales Plan have been executed, or (3) such time as the Glance 10b5-1 Sales Plan is otherwise terminated according to its terms.

No other “officer” (as defined in Rule 16a-1(f) under the Exchange Act) or director of the Company adopted, modified orterminated “Rule 10b5-1 trading arrangements” and/or “non-Rule 10b5-1 trading arrangements” (each as defined in Item 408 of Regulation S-K) during the three months ended September 30, 2025.