Free professional email signature tool with hub-and-satellite SSO
Project Overview
What We Worked On
- Hub-and-Satellite SSO Architecture
- Cross-Domain Authentication
- Edge Functions for Token Exchange
- Professional Signature Builder
- Zero-Config User Experience
Background
Email Signature Generator was built as both a useful free tool and a technical showcase of our hub-and-satellite SSO architecture. It demonstrates how satellite apps can leverage dot2.solutions as a central authentication hub, enabling seamless cross-domain login without requiring users to create separate accounts.
The Challenge
- Cross-domain authentication — localStorage and cookies are domain-isolated, making traditional session sharing impossible.
- User friction — Requiring separate logins for each subdomain creates poor user experience.
- Security requirements — Token exchange must be cryptographically secure and time-limited.
- Session propagation — Logout must cascade across all connected satellite apps.
The Solution
Phase 1: SSO Architecture Design
Designed a hub-and-satellite model where dot2.solutions serves as the central authentication hub. Satellite apps redirect unauthenticated users to the hub for login.
Phase 2: Secure Token Exchange
Built Edge Functions for secure token generation and exchange. Tokens are single-use, expire in 60 seconds, and are cryptographically signed to prevent tampering.
Phase 3: Federated Logout
Implemented federated logout that propagates across all satellite apps, ensuring consistent session state.
Phase 4: Signature Builder
Created an intuitive signature builder with real-time preview, multiple templates, and easy copy-to-clipboard functionality.
Results
Token exchange
Near-instant
N/A<200ms
Auth issues
Perfect reliability
N/A0
User accounts
Single sign-on
SeparateShared
User friction
Seamless
Multiple loginsZero
- Technical showcase: Demonstrates advanced SSO patterns for the portfolio
- Free tool: Provides value to users while showcasing capabilities
- Reusable architecture: SSO system can be applied to future satellite apps
Technology Stack
Lovable
SupabaseWhat's Next
- Additional satellite apps using the same SSO architecture
- Signature analytics and usage tracking
- Team signature management features
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