ASHRAE offers free, read-only access to a select number of their "current popular standards" and standards referenced in code.
ANSI University Outreach Program
ANSI's outreach program educates and advises faculty about standards in the classroom and in curriculum. Through this program, faculty and students can get complimentary access to a defined group of ISO or IEC standards for the duration of a course.
Incorporated by Reference (IBR) Standards Hosted by ANSI
Incorporation by reference (IBR) allows Federal agencies to comply with the requirement to publish rules in the Federal Register and the Code of Federal Regulations (CFR) by referring to materials already published elsewhere. This ANSI portal provides free access to select read-only, full-text standards incorporated by reference in U.S. federal regulations.
National Institute of Standards and Technology (NIST) Free Standards List
NIST offers a list of standards bodies that make some or all of their standards free, or free with membership.