Vital records are only available through the Office of the City Clerk. They may also be requested online or by mail. More information is available at https://www.sanantonio.gov/municipal-archives-records/birth-death-records.
Office of the City Clerk
210.207.8781
719 S. Santa Rosa, San Antonio, TX 78204
Ordering Birth Certificates Online:
https://www.dshs.texas.gov/vs/reqproc/Ordering-Birth-Certificates-Online.shtm
or
https://vitalchek.com
Applying for a Birth Certificate by Mail
https://www.sanantonio.gov/Municipal-Archives-Records/Birth-Death-Records#13108673-apply
Search for birth and death dates through the City of San Antonio Vital Records Index
https://www.sanantonio.gov/municipal-archives-records/birth-death-records/vital-records-index