Relay: A Developer-Focused SMS API Platform

Relay is a full-stack SMS API and messaging platform created for developers, businesses, agencies, and service providers that need a centralized way to send, manage, and monitor SMS communications.

The platform combines easy-to-use messaging interfaces with developer-focused API capabilities. Users can send individual or bulk SMS messages, review messaging history, manage balances and packages, generate secure API keys, and access technical documentation from a dedicated dashboard.

Administrators receive centralized control over users, SMS packages, balance allocations, connected gateway devices, SMTP configuration, platform content, and operational settings.

The Challenge

Managing an SMS service involves more than providing a message-sending form. The platform must coordinate user balances, messaging history, gateway capacity, API access, account security, packages, administrative operations, and system health.

Relay was created to bring these responsibilities into one cohesive platform while maintaining a clean user experience for both technical and non-technical users.

Project Objectives

The primary objectives were to:

Provide reliable single and bulk SMS interfaces
Offer secure API access for external applications
Centralize gateway device and balance management
Separate user and administrator responsibilities
Provide transparent messaging and transaction histories
Simplify package and user-allocation management
Monitor system capacity and gateway availability
Deliver a polished experience across desktop and mobile devices
Establish a maintainable foundation for future expansion

Messaging and User Experience

Relay provides an organized dashboard where users can access the platform’s essential messaging and account-management features.

Core user capabilities include:

Sending individual SMS messages
Sending bulk SMS campaigns
Reviewing complete messaging history
Viewing account balance and package information
Generating and managing API keys
Accessing integrated API documentation
Managing account and security settings
Recovering passwords and verifying email addresses
Switching between responsive light and dark themes

Developer API

Relay is designed to support developers who need to integrate SMS capabilities into websites, mobile applications, SaaS products, and internal business systems.

The developer experience includes:

Secure API-key generation
Centralized API-key management
Integrated API documentation
REST-based messaging endpoints
Structured authentication and authorization
Clear access to account balance and messaging information
A scalable foundation for additional integration capabilities

Administration and Operations

The administrative dashboard provides centralized control over the platform’s users, messaging infrastructure, and business configuration.

Administrators can manage:

Registered users and account roles
SMS packages and pricing configurations
User balances and SMS allocations
System-level SMS balance
Connected gateway devices
Active and inactive device states
SMTP and email-delivery settings
Public website content
Authentication and system configuration
Platform-wide operational settings

Gateway and Capacity Monitoring

Relay includes gateway monitoring and capacity-reporting capabilities to help administrators understand the current condition of the messaging infrastructure.

The system can track:

Active and inactive gateway devices
Available SMS balances across devices
User balance allocations
Remaining platform reserves
Overall gateway availability
System capacity and reserve health

These metrics can be compiled into automated operational reports and delivered directly to a configured Telegram channel through a secured REST endpoint.

Automated Telegram Reports

Relay provides an authenticated system-report endpoint for generating real-time operational summaries.

Reports may include:

Active and inactive SIM balances
Total available device balance
Current user allocations
Remaining SMS pool reserves
Platform reserve-health indicators
Active and inactive gateway counts
Report generation date and time

The reporting endpoint supports an authenticated administrator session or a protected bearer secret, making it suitable for scheduled jobs and secure monitoring services.

Authentication and Access Control

Relay includes a complete authentication workflow designed to protect user accounts and administrative functionality.

Implemented capabilities include:

Standard account registration and login
Google OAuth authentication
Email verification
Password recovery
Role-based authorization
Protected user and administrator routes
Secure server-side validation
Automatic first-administrator assignment during initial deployment

The first registered account can automatically receive the administrator role, simplifying the initial platform setup. All subsequent registrations receive the standard user role unless changed by an authorized administrator.

Performance and Architecture

Relay was migrated from a Vite-based React application to a modern Next.js App Router architecture.

The migration introduced:

Server and Client Component separation
Composed layouts for public, user, and administrator sections
Dynamic application routing
Improved server-side capabilities
Optimized database access
Reusable interface components
Structured content models
Database indexing
Server-side caching
A cleaner and more maintainable project structure

Design System

Relay uses a custom design system created with Tailwind CSS and Radix UI primitives. The interface focuses on clarity, accessibility, responsiveness, and consistency.

Design features include:

Responsive desktop and mobile layouts
Light and dark themes
Reusable buttons, cards, dialogs, forms, and navigation components
Consistent semantic color tokens
Accessible Radix UI primitives
Framer Motion micro-interactions
Lucide-based iconography
Clear separation between user and administrator experiences

Technology Overview

AreaTechnologiesFrontendNext.js, React and TypeScriptBackendNext.js server architecture and Node.jsDatabasePostgreSQL with Prisma ORMStylingTailwind CSSComponentsRadix UI and custom design-system componentsAuthenticationCredentials, Google OAuth and email verificationAdministrationFirebase Admin SDKAnimationFramer MotionIconsLucide ReactAPIREST API with API-key authenticationReportingTelegram Bot APIArchitectureNext.js App Router with Server and Client Components

Result

Relay brings messaging, developer APIs, balance management, gateway monitoring, user administration, and operational reporting into one unified system.

The final platform provides a streamlined experience for users sending messages, a practical integration layer for developers, and comprehensive administrative controls for managing the underlying SMS operation.

Its modular architecture and reusable design system also provide a strong technical foundation for adding future messaging providers, analytics, automation, billing, and integration capabilities.

Designed and developed by Monjel Morshed Sabbir through MMS Studio.