144 0001783984 XXXXXXXX LIVE 0001561550 Datadog, Inc. 001-39051 620 8th Avenue, 45th Floor New York NY 10018 8663294466 ALEXIS T LEQUOC Director Officer Class A Common Morgan Stanley Smith Barney LLC Executive Financial Services

1 New York Plaza 8th Floor New York NY 10004

53912 10767304.64 325443373 11/11/2025 NASDAQ Class A Common 11/11/2025 Exercise of Stock Options Issuer N 10688 11/11/2025 Cash Class A Common 06/01/2021 Restricted Stock Units and Performance Stock Units Issuer N 43224 06/01/2021 N/A N 10b5-1 Sales for ALEXIS T LEQUOC

620 8th Avenue, 45th Floor New York NY 10018

Class A 10/01/2025 41468 6259027.74 10b5-1 Sales for ALEXIS T LEQUOC

620 8th Avenue, 45th Floor New York NY 10018

Class A 09/02/2025 41468 5549532.55 ALEXIS T LEQUOC

620 8th Avenue, 45th Floor New York NY 10018

Class A 09/02/2025 13884 1858328.97 The securities to be sold were acquired upon the vesting of restricted stock units and performance stock units during the period of 6/1/2021 through 9/1/2024. Securities to be sold, acquired through RSU/PSU or upon option exercise, were registered on Form S-8 Sales that were executed on November 11, 2025 are being reported on this Form 144 filed on November 12, 2025 given the EDGAR system was not accepting filings on November 12, 2025 in observance of the federal holiday. 11/11/2025 06/13/2025 /s/ Alexis T. Le-Quoc