Sigil’s source code can be found on GitHub. Sigil is open source and licensed under the GPLv3. We’re very open to contributions and that’s how the project keeps itself running. Feel free to discuss ideas using the issue tracker before issuing pull requests.
Starting with Sigil v0.9.9, the Git tags and source archives used for Sigil releases are signed with Doug Massay’s PGP Key. His public key can be found and retrieved from any public key server. The fingerprint for his public key is:
B5A5 6206 AB0F BC1A 24EF AB8A A166 D29A 8FCD AC63