The Boston Almanac for 1841 lists the following architects working in Boston, from a survey "collected about the 1st of October, 1840". I have added links to some of their work.
Benjamin, A. Tremont, cor. Court Street
Asher Benjamin (1773-1845) published several architectural pattern books and is well known for his churches, including the Old West Church, Cambridge & Lynde St. (1806) The building was used as a church until 1896 when it became the West End Branch of the Boston Public Library. The pulpit was removed and installed in First Parish Church, Dorchester in 1897 when that parish's sixth meeting house was constructed. A congregation returned to Old West in 1962.
Bryant, G. J. F. 4 Court
Gridley James Fox Bryant is known as one of the primary proponents of the Boston "Granite Style". His work includes the Old Suffolk County Jail, Old Boston City Hall (1862-65, with Arthur Gilman), the Quincy School (1847), and Arlington Street Church (1860, with Arthur Gilman) and portions of the Boston City Hospital complex. Bryant and Gilman also devised a gridiron street pattern for the Back Bay.
Bond, Richard. Suffolk Buildings
Richard Bond (1797-1861) designed several buildings no longer extent within Boston, the Salem City Hall (1837) as well as several academic buildings at Harvard and Oberlin Colleges.