Bablu Kumar Singh

Backend Engineering & Systems Design

Deep-diving into high-performance architectures, data modeling, event streams, and security boundaries.

System Topologies

Interactive Request Lifecycle

Follow the step-by-step path of a request through the system

1. DNS / CDN

Gateway stage

Cloudflare resolves domain names, intercepts DDoS attempts, and serves cached static assets directly at the edge.

Estimated Overhead:1-5ms
Status Check:Active

SaaS Multi-Tenant Database ERD

Analyze schemas, keys, and foreign relational bindings

Tenants
Collection
id
UUID
name
VARCHAR(100)
subdomain
VARCHAR(50)
stripe_customer_id
VARCHAR(100)
created_at
TIMESTAMP
Users
Collection
id
UUID
tenant_id
UUID
email
VARCHAR(255)
password_hash
VARCHAR(255)
role_mask
INTEGER
created_at
TIMESTAMP
Subscriptions
Collection
id
UUID
tenant_id
UUID
stripe_sub_id
VARCHAR(100)
status
VARCHAR(50)
plan_tier
VARCHAR(50)
expires_at
TIMESTAMP

Tenants Schema

Stores company workspaces & domains
Relational Bounds
Parent workspace node (Has many Users and Subscriptions)
Primary Indexes
  • id:Primary unique identifier
  • subdomain:Subdomain routing identifier
Hover over tenant_id fields to highlight relationships.

Core Competencies

API Design & Lifecycle

Designing resilient REST and GraphQL APIs with strict semantic versioning, request validation using Zod schemas, structured error handling middleware, and comprehensive logging. We build request pipelines that intercept requests, sanitize payloads, enforce rate-limits, validate authorization tokens, execute controller actions, and output clean client responses.

Database Architecture & Caching

Implementing relational and non-relational database structures (PostgreSQL + MongoDB) configured with optimal indexing, connection pools, and transaction controls. Using Redis as a high-speed cache-aside store to optimize read queries, manage distributed sessions, and queue transient workloads.

Access Control (RBAC) & Tenancy

Constructing secure tenant isolation environments for SaaS setups alongside robust Role-Based Access Control (RBAC). Custom middleware evaluates authorization bitmasks in real-time, preventing cross-tenant data leaks and securing system administrative scopes.

Event-Driven Systems & Scalability

Handling high-concurrency event pipelines using Redis streams, RabbitMQ, or Kafka brokers. Decoupling resource-heavy workflows (e.g. payment processing, webhooks, analytics calculations) from core API request execution threads using worker pools.

Docker & AWS Cloud Infrastructure

Containerizing application processes with Docker multi-stage builds to minimize image sizes. Deploying secure infrastructure to AWS using EC2, Application Load Balancers, RDS database instances, Auto-Scaling Groups, and CI/CD pipelines to guarantee high availability and fail-safe releases.

Asynchronous Broker Event Queue

Simulate background event streams decoupling resource-heavy operations from API request threads

API Client
Redis Broker
Worker Pool
Broker Console logs
  • System ready. Event Broker initialized.
Queue depth: 0 items pending