Built a mobile app that generates cryptographically verifiable proof of completed service work. Before/after photos hashed with SHA-256, signed with Ed25519, timestamp anchored via freetsa (RFC 3161 compliant), GPS coordinates embedded. Client side verification only. No backend trust required. Signatures verified locally in an ephemeral memory sandbox. Any tampering in photos, timestamps, GPS or metadata immediately invalidates the signature. Stack: React Native, Golang, Ed25519, SHA-256, RFC 3161 TSA, AI work narratives via Groq. Built for the gig economy trust problem. Target markets: contractors, cleaners, delivery, property management. Looking to sell full IP and source code. mozar.t@yahoo.com