Stashcat is GDPR-compliant and ISO 27001-certified, and is widely deployed across German public administration and law enforcement. Its compliance model explicitly supports employer-side chat auditing in some deployments, which fits regulated public-sector oversight but differs from a strict, exception-free encryption model. If your organization needs encryption guarantees that hold the same way in every deployment, no built-in audit-access path to configure around, Wire's default E2EE model is built for that from the ground up.

Wire supports native federation with granular access controls across organizational backends. Stashcat's federation runs over the Matrix protocol, which limits interoperability to other Matrix-based messengers rather than Wire's broader cross-backend model. For organizations that need to collaborate securely across a wider range of partners, agencies, or vendors — not just others on the same protocol — Wire's federation model is the more flexible fit.

Wire uses MLS, a modern IETF standard designed for scalable group encryption with forward secrecy. Stashcat's core encryption is a conventional AES-256/RSA-4096 hybrid; it separately uses the Matrix protocol, but only for federation with other Matrix-based tools, not as its native encryption scheme. Wire's fully open-source codebase also means that architecture can be independently verified, rather than taken on trust.

Stashcat offers encrypted calling, with conferencing handled through a Jitsi integration limited to smaller group sizes - max. 75 participants. Wire's calling is natively end-to-end encrypted and secured with MLS at much larger scale — up to 2.000 participants — so teams that regularly run large, sensitive conferences won't hit the same ceiling.