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UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 ( Mark One ) □ ANNUAL REPORT UNDER SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended September 30 , 2021 □ TRANSITION REPORT UNDER SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from Delaware State or other jurisdiction of incorporation or organization X Title of each class Common Stock , $ 0.001 par value Form 10 - K 100 Sylvan Road , Suite G700 Woburn , Massachusetts ( Address of Principal Executive Offices ) Bridgeline Digital , Inc. ( Exact name of registrant as specified in its charter ) per OR share Commission File Number 333-139298 to 52-2263942 IRS Employer Identification No. BLIN ( 781 ) 376-5555 ( Registrant's telephone number , including area code ) ( Former name , former address and former fiscal year , if changed since last report ) Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol 52-2263942 IRS Employer Identification No. 01801 ( Zip Code ) Name of exchange on which registered The NASDAQ Stock Market , LLC Securities registered pursuant to Section 12 ( g ) of the Act : None Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . Yes Indicate by check mark if the registrant in not required to file reports pursuant to Section 13 or Section 15 ( d ) of the Act . No No Yes Indicate by check mark whether the registrant : ( 1 ) has filed all reports required to be filed by Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 , as amended ( “ Exchange Act " ) during the preceding 12 months ( or for such shorter period that the registrant was required to file such reports ) , and ( 2 ) has been subject to such filing requirements for the past 90 days . Yes > No Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S - T ( §232.405 of this chapter ) during the preceding 12 months ( or for such shorter period that the registrant was required to submit . Yes No Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S - K is not contained herein , and will not be contained , to the best of registrant's knowledge , in definitive proxy or information statements incorporated by reference in Part III of this Form 10 - K or any amendment to this Form 10 - K . □