As filed with the Securities and Exchange Commission on October 6, 2025 Registration No. 333-289725 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 AMENDMENT NO. 3 TO FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 iSpecimen Inc. (Exact name of registrant as specified in its charter) (State or jurisdiction of incorporation or organization) (Primary Standard Industrial Classification Code Number) Delaware 8731 27-0480143 (IRS Employer Identification No.) 8 Cabot Road, ...

As filed with the Securities and Exchange Commission on August 20, 2025 Registration No. 333- UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 (Primary Standard Industrial Classification Code Number) Delaware 8731 27-0480143 (IRS Employer Identification No.) FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 iSpecimen, Inc. (Exact name of registrant as specified in its charter) (State or jurisdiction of incorporation or organization) 8 Cabot Road, Suite 1800 Woburn, MA 0 ...