The Hedera services codebase is officially open source and can be found in the official GitHub repository: https://github.com/hashgraph/hedera-services You can read more about the open sourcing of Hedera services in this blog posting: https://www.hedera.com/blog/all-our-services-are-belong-to-you
The hashgraph platform is officially open source (Apache License 2.0) and has been audited by multiple code audit firms. The audit from FP Complete for the hashgraph consensus platform code, as well as the COQ proof from Carnegie Melon, are made available on the 'Audits and Standards' page: https://hedera.com/audits-and-standards. Open source ensures that the source code is made available for anyone to read, recompile, and verify that it is correct.
