Franz Geffke
Remote, Lisbon (GMT +1)
mail@gofranz.com • gofranz.com • GitHub
Fluent in English / German
I’m a systems architect and technical leader who ships. The protocols are the easy part now; what’s scarce is judgment: knowing what to build, what it costs you in a year, and when the confident answer is the wrong one. Currently Senior Identity Engineer at TWIN (IOTA Foundation), shipping OID4VP, SD-JWT VC, and a KERI/vLEI ↔ IOTA DID bridge for global trade. Before TWIN, principal engineer at Softmax: the digital identity platform now backing KYC across 10+ partner products, IoT remote patient monitoring (BLE/WebRTC), and a regulated crypto exchange. 14 years building products end to end and guiding the teams that deliver, sometimes as the founder.
My non-traditional path through international business and self-directed learning - 15+ years across Singapore, Thailand, Malaysia, China, Iran, UAE, Turkey, and Portugal - taught me to read users, markets, and the business impact of a technical call. I design and build secure, scalable platforms end to end, turning ambiguous goals into simple, reliable systems. AI makes me fast, but the aim is mine: I’m the driver, not the passenger. I’m at my best in high-ownership, fast-moving environments, because this is more than a job to me.
TECHNOLOGY STACK
- Identity & Trust: OID4VP/OID4VCI, SD-JWT VC (selective disclosure, KB-JWT holder binding), DCQL, JARM, W3C Verifiable Credentials (issuer + verifier), Bitstring Status List, KERI/ACDC/IPEX, vLEI, DID (
did:iota,did:webs), OIDC/CIBA, OAuth 2.0, EUDIW (HAIP profile), trust frameworks, Casbin (ABAC/RBAC), Argon2, X.509/PKIX - Languages: TypeScript/JavaScript, Rust, Python, Move (IOTA)
- Platforms: Node.js (Fastify, NestJS, Express), Rust (Actix Web, Diesel), Next.js (App Router), React, Vue, React Native
- Infrastructure: PostgreSQL, MySQL, ClickHouse, Redis, HashiCorp Vault, Docker, AWS, Guix (reproducible builds)
- Other Protocols: WebRTC, JWS/JWE/JWT, WebSockets, Nostr
WORK EXPERIENCE
Senior Identity Engineer at TWIN (IOTA Foundation)
2025 - Present
Building the digital identity platform for global trade - bridging GLEIF/vLEI, EU eID, and country-specific KYC with decentralized identity on IOTA.
- GLEIF vLEI ↔ IOTA DID two-way binding - no off-the-shelf bridge between these trust roots, so I built one:
- Bidirectional cryptographic linkage between GLEIF’s KERI/vLEI ecosystem and IOTA DIDs (
did:iota,did:webs): a self-issued Designated Aliases ACDC anchored in the Legal Entity’s KEL/TEL, plus an on-chain W3C VC JWT carrying the KERI anchor seal (KELanc+ TELissSAIDs), verified by three independent on-chain authority checks. - Full-stack: Move contract (VleiAttestation), Express/Node backend, React 19 + Vite frontend running
signify-tsin the browser (keys never leave the device), Sally verifier integration.
- Bidirectional cryptographic linkage between GLEIF’s KERI/vLEI ecosystem and IOTA DIDs (
- Identity platform on Keycloak - Keycloak as the OIDC authorization server for the TWIN identity stack:
- Extended Keycloak with a custom SPI for HashiCorp Vault-backed token signing.
- Multi-tenant IdP: per-realm and shared-realm tenancy, machine-to-machine service accounts
- Standard OIDC hardening:
private_key_jwtclient auth (RFC 7523), refresh-token rotation; JWKS verification at the edge. - Casbin ABAC + RBAC authorization, GDPR right-to-erasure, and a headless provisioning CLI.
- TWIN Notary - a credential trust anchor, whitepaper to a running service:
- OID4VCI 1.0 Final issuer (pre-authorized code flow) minting W3C VCDM 1.1
jwt_vc_jsoncredentials signed as adid:iotavia Vault, plus an OID4VP 1.0 Final verifier (DCQL) for permissionless presentation. - Dual-lane revocation: W3C Bitstring Status List over HTTPS and on-chain RevocationBitmap2022 in the issuer DID document, with configurable strict/resilient policy.
- Pluggable
INotaryProcesscore (initiate / advance / finalize) with two backings - contract attestation and KRA (Kenya Revenue Authority) / KYB business verification - plus signed verification-lineage claims across renewals.
- OID4VCI 1.0 Final issuer (pre-authorized code flow) minting W3C VCDM 1.1
- OID4VP verifier on the HAIP profile - interop-tested against the EUDI Reference Wallet:
- Implemented the
x509_hashclient ID scheme, SD-JWT VC verification with KB-JWT holder binding, DCQL queries, and JARMdirect_post.jwt(ECDH-ES JWE). - Caught three bugs in spec review: a silent KB-JWT skip, a JWE dual-version trap, and a DCQL PII leak.
- Implemented the
Principal Engineer / Technical Lead at Softmax Co., Ltd
2021 - Present
Built a digital identity platform for government use - now backing KYC across 10+ partner products. Currently advisory.
- OIDC/CIBA Identity Platform:
- Backend in TypeScript (NestJS) and Rust (Actix Web): authentication, digital signatures, push notifications.
- SDK libraries across TypeScript, Rust, C++, PHP, Python for auth flows, digital signatures, push notifications.
- Led engineering, ran technical integrations, and served as primary integration contact for partner orgs.
- Delivered IoT Healthcare Solution:
- BLE application for Bangle.js smartwatch + clinical dashboards for real-time patient monitoring.
- Patient gateway terminal: vital-signs REST API, WebSocket + WebRTC monitoring interface.
- Launched Crypto Exchange & NFT Marketplace:
- ERC-1155 NFT platform with integrated KYC for regulated digital asset trading.
- Multi-currency exchange with wallet management and order book logic.
- 99.9% Platform Uptime over 24 Months:
- Reproducible builds + deployment via Guix - no configuration drift.
- Containerized deployment (Docker, custom scripts) for 30+ microservices with monitoring.
Founder at goFranz
2019 - Present
Solo technical founder - five products, all still running, all paying their own bills. Nights and weekends since taking on TWIN.
- Checkoutbay.com - API-first e-commerce with multi-warehouse inventory.
- Formshive.com - Privacy-focused form backend with spam filtering for developers.
- GPTMuse.com - Privacy-first AI platform: pay-per-use access to ChatGPT, Claude, Gemini.
- PantherX.org - Lightweight Linux distribution on GNU Guix; declarative system configuration.
- nostr-ts - Open-source TypeScript SDK for the Nostr protocol.
Co-founder & CTO at Sky-Hype AG (Global real estate social platform)
2016 - 2020
Co-founded a global real estate social platform - ran the build, the hiring, the investor pitches, and early customer outreach. Wound down in 2020.
- Scaled platform to 50,000 daily active users. Built the social/search platform from scratch - Vue.js frontend, NestJS/Flask backend.
- Secured seed funding - pitched investors, defined technical roadmap.
- Onboarded realtors by running technical integrations personally; built engineering + sales teams.
Software Engineer at DKKMA Ltd.
2013 - 2016
Hands-on client work - from first call to delivery.
20+ custom web projects (Bootstrap, CMS integrations); analytics dashboards (Metabase, Google Analytics, MySQL).
Earlier Experience
2010 - 2013
Infrastructure and integration roles at Q-Windows Thailand, MJM Networks Singapore, and VBH Hardware China.