Cover - shares	3 Months Ended	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2021	Jul. 30, 2021
Cover [Abstract]
Document Type		10-Q
Document Quarterly Report		true
Document Transition Report		false
Document Period End Date		Jun. 30, 2021
Entity File Number		000-23970
Entity Registrant Name		FALCONSTOR SOFTWARE, INC.
Entity Incorporation, State or Country Code		DE
Entity Tax Identification Number		77-0216135
Entity Address, Address Line One		701 Brazos Street
Entity Address, Address Line Two		Suite 400
Entity Address, City or Town		Austin
Entity Address, State or Province		TX
Entity Address, Postal Zip Code		78701
City Area Code		631
Local Phone Number		777-5188
Entity Current Reporting Status	Yes
Entity Interactive Data Current		Yes
Entity Filer Category		Non-accelerated Filer
Entity Small Business		true
Entity Emerging Growth Company		false
Entity Shell Company		false
Entity Common Stock, Shares Outstanding			7,074,364
Entity Central Index Key		0000922521
Amendment Flag		false
Current Fiscal Year End Date		--12-31
Document Fiscal Period Focus		Q2
Document Fiscal Year Focus		2021