Architecture

From CISO to Full-Stack Developer: Building TopFlow in 4 Weeks

After 15 years in security leadership, I built a production AI workflow tool from scratch. Here's what I learned transitioning from strategic security to hands-on development.

November 25, 2025
11 min read

The CISO Stereotype

There's a common assumption in tech: once you reach the C-suite in security, you stop coding. CISOs are seen as strategic thinkers but who couldn't build a production application if their careers depended on it.

The 4-Week Build Timeline

Here's how I structured the development process:

Week 1: Architecture & Security Design

  • Designed privacy-first architecture (no database)
  • Created 5-layer security model
  • Mapped OWASP Top 10 mitigations

Week 2: Core Workflow Engine

  • Built drag-and-drop canvas with React Flow
  • Implemented 10 node types
  • Added cycle detection and validation

Week 3: Security Hardening

  • Implemented SSRF prevention
  • Added rate limiting with Redis
  • Configured security headers

Key Lessons Learned

Security Expertise Translates to Code Quality

My security background meant I naturally wrote defensive code: input validation everywhere, proper error handling, timeout enforcement.

Conclusion

Building TopFlow proved that security expertise makes you a better developer, and that hands-on development makes you a better security leader.

About the Author

Charlie Su is a former ciso & topflow creator. With extensive experience in cybersecurity and compliance, Charlie combines strategic security leadership with hands-on technical expertise.