Codify SaaS Blog - Page 8
Code-first guides and deep dives on building B2B SaaS products, designing APIs, scaling web apps, and modernizing legacy software.
10 Oracle to PostgreSQL Migration Challenges Solved
Oracle to PostgreSQL migration challenges — empty strings as NULL, DATE includes time, NUMBER without precision, PL/SQL packages, CONNECT BY, sequences, outer joins, and tooling surprises with code examples.
5 Steps to Modernize Legacy Java Without Rewriting
Legacy Java modernization without rewriting — 5-step guide covering assessment, characterization tests, Strangler Fig pattern, database migration, and decommissioning with real code examples.
How We Migrated a 10-Year-Old Java Monolith to a Modern Stack — Full Story
Java monolith migration to modern NestJS/Next.js stack — Strangler Fig pattern, REST API facade, Oracle to PostgreSQL migration, module extraction timeline, and honest lessons from a 14-month project.
7 Essential Java Enterprise Patterns for TypeScript
Java enterprise patterns implemented in TypeScript — Repository, Unit of Work, Domain Model, Specification, Service Layer, Factory, and Observer patterns with NestJS code examples for better SaaS codebases.
Add REST API Legacy Java Application Without Refactoring
How to add a REST API to a legacy Java application without refactoring the core — facade pattern, Spring Boot layer, JWT auth, transaction management, error translation, and testing approach with code examples.
Zero Downtime Deployment NestJS Blue Green Rolling Strategy
How to deploy NestJS with zero downtime using rolling updates and blue-green strategies — graceful shutdown with NestJS shutdown hooks, health checks, database migration patterns, and rollback automation.
NestJS Next.js CI/CD GitHub Actions Configuration
Real GitHub Actions workflow files for NestJS backend and Next.js frontend — caching, parallel jobs, environment-specific deployments, database migrations, rollback, and Slack notifications.
Environment Variable Management SaaS Production Security
How to manage environment variables across local dev, staging, and production for a SaaS built on NestJS and Next.js — .env safety, ConfigService validation, secrets rotation, and feature flags.
Docker NestJS Multi-Stage Build Production Optimization
Production-optimized Dockerfile for NestJS with multi-stage builds. Real size reduction numbers, health checks, non-root security, and Docker Compose setup.
Redis Caching Strategy for SaaS — What We Cache, What We Don't, and Why
Adding Redis to a SaaS is easy. Knowing what to cache, what not to cache, and when to invalidate it is the hard part. Here is our Redis caching strategy for NestJS — cache-aside pattern, TTL decisions by data type, tag-based invalidation, stampede protection, tenant namespacing, and hit-rate monitoring.
PostgreSQL Performance for SaaS — 8 Query Optimizations From a Real Slow Dashboard
The dashboard took 8 seconds to load and the client was, reasonably, unhappy. We did not shard the database or add caching or rewrite anything. We fixed the wrong index, killed an N+1, and replaced a correlated subquery. Eight seconds became 340ms. Here is exactly how.
Building a Real-Time Notification System — WebSockets vs SSE vs Polling in NestJS
Most SaaS teams reach for WebSockets the moment they need any real-time behaviour. Often they need SSE. Sometimes they just need polling. Here are all three implementations in NestJS with the exact decision framework for when each makes sense.