How it's built
System Overview
Eli is built as a modern, cloud-native SaaS platform designed for global enterprise deployment. Our architecture prioritizes security, scalability, and compliance while maintaining high availability across multiple geographic regions.
System Architecture Diagram
Note: This diagram provides a simplified view of Eli's core architecture and its purpose is not to display all of its sub-processors. For a complete list of sub-processors and third-party services we work with, please refer to our Who We Work With page.
Application Architecture
Application layer
Admin app (Front only) - app.eliapp.io
Purpose: Campaign management interface for organizational administrators, HR teams, and communication managers
Technology: Next.js 15.2, React 19, TypeScript, Tailwind CSS
Platform: Any browser, ES2022
Key Features: Campaign creation, analytics dashboard, user management, content authoring
Authentication: Multi-method support through Eli Authentication Service
API Integration: Consumes Admin API
Employee app (Front only) - my.eliapp.io
Purpose: Employee engagement platform for campaign participation, content consumption and employee interaction
Technology: Next.js 15.2, React 19, TypeScript, Tailwind CSS
Platform: Any browser, ES2022
Key Features: Campaign participation, progress tracking, interactive challenges, online communities
Authentication: Multi-method support through Eli Authentication Service
API Integration: Consumes User API
Mobile app - m.eliapp.io
Purpose: Employee engagement platform for campaign participation and content consumption and employee interaction
Technology: Flutter framework for cross-platform deployment
Platforms: Native iOS and Android applications
Key Features: Campaign participation, progress tracking, enhanced interactive challenges, online communities, offline capabilities, push notifications, deep linking
Authentication: Multi-method support through Eli Authentication Service
API Integration: Consumes User API
Auth app (Full-stack) - auth.eliapp.io
Purpose: Centralized authentication and session management for other Eli apps
Technology: Next.js 15.2, React 19, Firebase Auth integration
Features: SSO support, session management, security token generation
Integration: Validates all requests across the platform ecosystem
Authentication methods:
Sign in With Google
Sign in With Apple
Email / password
OTP via email
API app (Back only) - api.eliapp.io
Framework: Express.js with Node.js runtime
API Design: tRPC (Type-safe Remote Procedure Calls) for end-to-end type safety
Architecture: Microservices pattern with three dedicated API endpoints:
User API (
/trpc/user): Employee-facing features and mobile app support. Cookie-based auth.Admin API (
/trpc/admin): Administrative functions and campaign management. Cookie-based auth.Service API (
/trpc/service): External integrations, webhooks, and system callbacks. 164-chars Bearer tokens auth.
Data layer
Our database: MongoDB Atlas
Configuration: 3-replica set for high availability and data redundancy
Location: Google Cloud Platform, Belgium region (europe-west1)
Features: Automatic failover, point-in-time recovery, encryption at rest
ORM: Prisma for type-safe database access and schema management. Prisma schemas (and API schemas) are shared to all apps through internal packages for bullet-proof consistency and safety.
Our file storage: Firebase storage
Location: Belgium (europe-west1)
Use Cases: User profile pictures, images shared in posts,...
Infrastructure & Hosting
Our primary hosting platform: Vercel
Location: Paris, France (AWS eu-west-3 region)
Features:
Global CDN with edge computing capabilities
Automatic scaling based on traffic demand
Built-in DDoS protection and security filtering
Zero-downtime deployments
Our queue management system: Upstash Qstash
Use Cases: Email sending, Push Notifications, background processing, scheduled tasks
Features: Automatic retries, dead letter queues, monitoring and observability
Our email delivery system: Resend
Location: Ireland (AWS eu-west-1 region)
Use Cases: Transactional emails, campaign notifications, OTP delivery, system alerts
Features: High deliverability rates, webhook support, email analytics, API-first design
Scalability & Performance
Auto-scaling capabilities
Application layer: Automatic horizontal scaling on Vercel based on traffic demand
Database: MongoDB Atlas auto-scaling with performance optimization
Queue system: Distributed processing with automatic retry mechanisms
CDN: Global edge locations for optimal content delivery all around the globe
Data Residency & EU compliance at a glance
Web Services: Hosted in Paris, France (AWS eu-west-3 CDG1)
Database: Hosted in Belgium (GCP europe-west1)
Compliance: GDPR-compliant by design with EU data residency
Security: All communications over HTTPS/TLS 1.3 encryption
Development & Deployment
Version control
We use Gitlab for all our projects.
Continuous Integration & Deployment
Web apps (all of them)
Vercel CI pipeline for build automation and deployment
Zero-warning linting policy at high standards
Staging environments and rollback capabilities
Android app
Gitlab CI pipeline for build automation and Play Store deployment
Zero-warning linting policy
Staging environments and rollback capabilities
iOS app
Gitlab CI pipeline for build automation and App Store deployment
Zero-warning linting policy
Staging environments and rollback capabilities
Technology Stack Summary
Frontend & mobile: Next.js 15.2, React 19, TypeScript, Tailwind CSS, Flutter Backend: Node.js, Express.js, tRPC, Prisma ORM Database: MongoDB Atlas (3-replica set) Authentication: Firebase Auth Storage: Firebase Storage Queue: Upstash QStash Email: Resend Hosting: Vercel (Paris), GCP (Belgium) CI/CD: Vercel, GitLab CI, XCode Cloud
For technical architecture questions, contact: [email protected]
Last Updated: August 2025
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