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Building a Scalable Buyer-to-Seller Live Chat

CHI Software built a high-performance buyer-seller chat development that streamlines communication, boosts user trust, and ensures the marketplace runs smoothly at scale. The solution enables instant message synchronization and automated moderation through secure live chat implementation, even during peak traffic.

Quick Project Facts and Key Achievements

Quick Project Facts

Client Industry

E-commerce / Online Marketplace / Classifieds Platform

Client Location

United Kingdom

Challenge

Migrating millions of messages and conversations into a new buyer-to-seller chat implementation.

Solution

An event-driven marketplace buyer-seller live chat platform with scalable messaging architecture, automated moderation, and optimized data processing.

Team Size

4 specialists

Timeline

June 2022 – Ongoing

Project Key Achievements

+20%

growth in deal closures by a faster messaging experience

+25%

user retention with buyer-to-seller chat implementation

40%

faster incident recovery through improved monitoring

-30%

operational cost reduction via custom live chat for marketplaces

Story Behind the Numbers

CHALLENGE

The interaction between buyers and sellers inside the online platform lacked proper real-time synchronization. Messages could be delayed, spam and scams slipped through, and the whole process wasn’t exactly user-friendly. 

With millions of active users, the client needed a custom live chat for marketplaces capable of handling high concurrency, ensuring secure data exchange, and delivering seamless real-time conversations across every app and device.

ENGAGEMENT STAGE

We joined during an active transformation phase to lead the buyer-to-seller chat implementation and redesign the messaging architecture. The focus was on making every message count: delivered instantly, safely, and across web and mobile. At the same time, we streamlined behind-the-scenes processes so the team could spend less time fixing issues and more time building new features.

TRANSFORMATION

Overall, the platform became faster, safer, and better positioned to grow with the business after the full live chat implementation. Users get messages in real time, notifications are personalized, and fraud is automatically blocked within the secure chat environment.

SERVICES PROVIDED

DEVELOPMENT TEAM

  • 4 Java Developers

Key Areas for Improvement

DIRECT MESSAGING IMPLEMENTATION

Communication required a secure, instant messaging system to eliminate delays and ensure immediate synchronization across all user devices.

ENHANCED LISTINGS AND TRANSACTION WORKFLOWS

Marketplace interactions needed simplification through faster listing management and more reliable transaction updates supported by buyer-to-seller chat.

SAFER MARKETPLACE EXPERIENCE

Automated fraud detection and GDPR-compliant data handling strengthened user trust while improving platform security.

FASTER PLATFORM PERFORMANCE

Quicker page loads and optimized media rendering improved stability during high-traffic periods, ensuring a smooth marketplace experience.

AUTOMATED DATA PRIVACY

Manual handling of user data was replaced with automated GDPR workflows, making privacy requests more transparent and efficient.

INTELLIGENT USER NOTIFICATIONS

The platform introduced personalized, behavior-based messaging and push notifications to improve user engagement and communication.

Our Implementation Approach

STRATEGY

To achieve a reliable buyer-to-seller chat implementation, the project was divided into strategic phases focused on independence and performance.

DEVELOPMENT PHASES

01
Live Chat Implementation

A secure, proprietary messaging system was developed to enable real-time communication between buyers and sellers. A stabilization phase ensured reliable message delivery and consistent platform performance.

02
Backend and Microservices

Core services were developed and optimized across more than 200 microservices to improve scalability, performance, and system stability under growing workloads.

03
Monitoring and Incident Management

Monitoring, alerting, and distributed tracing were introduced to detect issues faster, minimize downtime, and improve the reliability of marketplace communication services.

04
Architecture and Feature Development

Scalable system components and new marketplace features were delivered while ongoing refactoring and testing reduced technical debt and improved long-term maintainability.

05
Production Reliability

Operational processes, logging, and telemetry were enhanced to accelerate incident resolution and strengthen overall platform resilience in production.

Technology Stack

  • Backend: Java 21, Python, Scala, Spring, Hibernate
  • Frontend: JavaScript
  • Mobile: Swift, Kotlin
  • Databases: PostgreSQL, Elasticsearch, Firebase
  • Cloud and Infrastructure: GCP, Kubernetes, Docker, Istio, Terraform
  • Messaging and Data Streaming: Kafka, Google Pub/Sub
  • CI/CD and DevOps: Jenkins, GitHub, GitHub Actions, Puppet, Maven, Liquibase, MapStruct
  • Testing and Monitoring: Mockito, JUnit, Testcontainers, Google Cloud Metrics, OpenAPI

Visual Highlights

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Product Features

01
Instant Communication Hub

Sub-second latency messaging enables instant synchronization across all user devices, supporting fast and efficient buyer-seller communication.

02
Intelligent Trust and Safety

Automated phishing and spam detection helps protect users, creating a safer and more reliable marketplace experience.

03
Behavioral Notification Engine

Personalized push and in-app notifications are triggered based on live user activity, improving engagement and response rates.

04
Optimized Listing Integration

Marketplace listings are directly linked to conversations, allowing buyers and sellers to manage interactions without leaving the chat experience.

05
High-Concurrency Infrastructure

A cloud-native architecture supports more than 14.8 million visitors while maintaining consistent performance during peak traffic periods.

06
Automated Privacy Workflows

GDPR-compliant processes automate privacy requests, ensuring secure, transparent, and efficient handling of user data.

07
Enhanced Media Rendering

Optimized caching improves page loading and high-resolution image rendering, creating a faster marketplace experience.

08
Consistent Status Tracking

Real-time delivery and read statuses provide clear visibility into every conversation, helping users track communication more effectively.

Measurable Improvements

+20% GROWTH IN SUCCESSFUL DEAL CLOSURES

A seamless marketplace buyer-seller live chat experience accelerated buyer–seller interactions, leading to more completed transactions and stronger marketplace activity.

-30% REDUCTION IN VENDOR & OPERATING EXPENSES

Eliminating costly third-party dependencies and streamlining compliance processes lowered ongoing operational spending.

+25% BOOST IN USER RETENTION

Advanced personalized communications increased the relevance of user touchpoints, encouraging repeat engagement and long-term loyalty through buyer-to-seller chat development.

40% QUICKER INCIDENT RECOVERY

Enhanced monitoring and structured response processes minimized service disruptions and safeguarded revenue during peak demand.

2x ACCELERATED TIME-TO-MARKET 

A more flexible and scalable foundation enabled faster deployment of product updates and business-driven improvements.

+30% IMPROVEMENT IN PLATFORM SATISFACTION METRICS

Higher performance, stable messaging, and a safer user environment strengthened customer trust and overall experience.

Interested in AdTech Data Management Platform Modernization?

CHI Software helps businesses create messaging platforms that connect users instantly, safely, and reliably. Our solutions enable buyer-to-seller chat development, making conversations smoother, reducing friction, and keeping your marketplace active and trustworthy.

What We Specialize In

  • Build high-performance real-time chat systems
  • Modernize communication workflows for online marketplaces
  • Deliver personalized notifications and activity-based alerts
  • Design cloud-ready infrastructures that scale with traffic

Businesses We Support

  • Online marketplaces and classifieds
  • E-commerce and retail platforms requiring scalable 
  • Startups and enterprises enhancing customer interactions

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