Starting in July 2025, the government will be releasing a new CNPJ format for companies in Brazil. Therefore, several systems will have to adapt to validate the entry of this new alphanumeric CNPJ format. This tool serves as support to speed up the process of adapting to the new CNPJ format.

useful links:

https://geradorbrasil.com/gerador-de-cnpj-alfanumerico/

https://www.gov.br/receitafederal/pt-br/acesso-a-informacao/acoes-e-programas/programas-e-atividades/cnpj-alfanumerico

https://www.gov.br/receitafederal/pt-br/centrais-de-conteudo/publicacoes/documentos-tecnicos/cnpj

source codes used as a basis:
https://www.gov.br/receitafederal/pt-br/centrais-de-conteudo/publicacoes/documentos-tecnicos/cnpj/codigos-cnpj.zip/view