Annual report pursuant to Section 13 and 15(d)

Document and Entity Information

Document and Entity Information - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2021
Mar. 10, 2022
Jun. 30, 2021
Cover [Abstract]      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Dec. 31, 2021    
Document Fiscal Year Focus 2021    
Document Fiscal Period Focus FY    
Trading Symbol CABA    
Entity Registrant Name CABALETTA BIO, INC.    
Entity Current Reporting Status Yes    
Entity Central Index Key 0001759138    
Entity Voluntary Filers No    
Current Fiscal Year End Date --12-31    
Entity Filer Category Non-accelerated Filer    
Entity Well-known Seasoned Issuer No    
Entity Shell Company false    
Entity Small Business true    
Entity Emerging Growth Company true    
Entity Ex Transition Period false    
ICFR Auditor Attestation Flag false    
Entity Common Stock, Shares Outstanding   28,977,129  
Entity Public Float     $ 205
Entity File Number 001-39103    
Entity Tax Identification Number 82-1685768    
Entity Address, Address Line One 2929 Arch Street    
Entity Address, Address Line Two Suite 600    
Entity Address, City or Town Philadelphia    
Entity Address, State or Province PA    
Entity Address, Postal Zip Code 19104    
City Area Code 267    
Local Phone Number 759-3100    
Entity Interactive Data Current Yes    
Title of 12(b) Security Common Stock, par value $0.00001 per share    
Security Exchange Name NASDAQ    
Entity Incorporation, State or Country Code DE    
Document Annual Report true    
Document Transition Report false    
Auditor Firm ID 42    
Auditor Name Ernst & Young LLP    
Auditor Location Philadelphia, Pennsylvania    
Documents Incorporated by Reference


Part III of this Annual Report on Form 10-K incorporates by reference certain information from the registrant’s definitive Proxy Statement for its 2022 annual meeting of shareholders, which the registrant intends to file pursuant to Regulation 14A with the Securities and Exchange Commission not later than 120 days after the registrant’s fiscal year end of December 31, 2021. Except with respect to information specifically incorporated by reference in this Form 10-K, the Proxy Statement is not deemed to be filed as part of this Form 10-K.