UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 __________________________________ FORM 10-K __________________________________ ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-38285 BANDWIDTH INC. (Exact name of registrant as specified in its charte ...