Secure Your APIs: OAuth2 and JWT for Beginners
Secure Your APIs: OAuth2 and JWT for Beginners APIs are frequent targets for bad actors since they expose data and functionality. Securing them whil…
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Spring Batch parallel processing and partitioning tutorial — Complete Guide
Spring Batch parallel processing and partitioning tutorial — Complete Guide A practical, in‑depth guide to Spring Batch parallel processing and part…
Building an Excel download API with TBEG and Spring Boot (Kotlin/Java)
In Part 3 , we explored TBEG's template syntax in depth. Now let's build an Excel download API with Spring Boot + TBEG - the most common real-world…
Spring Boot 3.5 Stopped Getting Patches in June. Don't Migrate to 4.0.
Two dates decide your next few weeks of Spring work: 30 June 2026 — Spring Boot 3.5 stopped getting free patches. 3.5.16 was the last one. 31 Decemb…
Building a Full RAG Pipeline in Spring Boot — From Ingest to Grounded Answer
Previous articles covered the individual pieces of RAG. You now know what embeddings are, how to chunk documents, and how Pinecone stores and search…
Polar Bear Cache: Fewer Remote Calls, More Ice 🐻❄️
I built Polar Bear Cache, a local caching library for Java and Spring applications, with a simple idea: serve frequently accessed data locally and r…
Role-Based and Permission-Based Access Control in Spring Security
Introduction Once authentication is solid, the next question is inevitable: what is this user actually allowed to do? Authentication proves who you…
IntelliJ Java Version Mismatch: Project SDK, Gradle JVM, and JAVA_HOME Explained
IntelliJ Java Version Mismatch: Project SDK, Gradle JVM, and JAVA_HOME Explained I recently set up a new development laptop from scratch. JDK 17 was…
Building Long-Running Payment Workflows with Spring Boot and NERV Event
Building Long-Running Payment Workflows with Spring Boot and NERV Event Some payment operations finish in milliseconds. Others don't. Imagine a paym…
The Database Tells You What Is. An Audit Trail Tells You What Happened
Something is wrong with a customer's account. You open the database and run: SELECT * FROM customer_account WHERE id = 12345 ; The row looks perfect…
MindCare: A Real-World Angular + Spring Boot Project You Can Actually Run and Explore
If you're learning Angular, Spring Boot, or full-stack development, you've probably faced this problem: You can find hundreds of tutorials , but fin…
Openspreader: The missing piece of Java concurrency. `java.util.concurrent`, scoped to the cluster.
Thirteen coordination primitives as one Spring Boot starter. The APIs you already know, spanning every instance of your application instead of one J…
Why I Built a Modern Spring Initializr Alternative with Visual JPA & Docker
Whenever I start a new Spring Boot project using standard tools like start.spring.io , the workflow usually looks like this: Select Spring Web, Spri…
Spring Boot's Hidden Secret for Configuration: EnvironmentPostProcessor
Spring Boot's Quiet Hook for Shipping Configuration: EnvironmentPostProcessor Hi everyone! This is Mikhail Polivakha, technical lead of the Axelix p…
If Your Spring AI Streams Die After 60 Seconds, It's Not Your Network
If you're on Spring AI 2.0.1 and your streaming calls die after about a minute with OpenAIIoException: Stream failed , stop debugging your proxy. Si…
The Silent Killer in Spring Boot: Why @Transactional Around Third-Party APIs Exhausts Your Connection Pool
It’s 03:00 PM on a Tuesday. Your monitoring dashboards go red. Incoming requests are timing out, HTTP 504 errors are spiking, and users are reportin…
Eliminating Race Conditions in Clustered Spring Boot with PostgreSQL Advisory Locks
It’s 02:14 AM. Your alert manager fires: an account balance dropped below zero, or a user received two trial credits instead of one. You trace the l…
I Removed an API Field. Hindsight Found Who Still Needed It.
API compatibility problems are rarely difficult because removing a field is technically hard. The difficult part is knowing who still depends on tha…
Building a Production-Ready Persistence Layer in Spring Boot
Spring Data JPA makes persistence remarkably easy to start with. Create an entity. Extend JpaRepository . Start writing business logic. public inter…
I Missed @Service in Node.js, So I Built It with Express
Let the browser console create the files At first, the browser console was only a debugging tool. I wrote the same create, read, update, and delete…
Your Search Query Is a Program: Composing Role-Based SQL With the Strategy Pattern
Every business application has this screen somewhere: a table of records, filter boxes above it, and a user who may only see part of the data. The f…
Silent Saves: How JPA Persists Your Changes Without You Asking
One of our junior devs wrote an API that was supposed to be “read-only” and act as an internal data funnel — pull some records, transform them, pass…
Stop Chasing Exactly-Once. Your Kafka Consumer Just Needs to Not Care
Every few months a team I talk to decides they need exactly-once delivery in Kafka. They read the docs, discover processing.guarantee=exactly_once_v…
Spring Security Beyond the Login Form: Data Isolation and the 401/403 Contract
Why This Article Exists There is a very common kind of application: it lives inside a company network, it is reachable over the VPN, and it has been…
Cronflower: run a DAG workflow across your cluster, instead of chaining cron jobs
Every team ends up here. One cron job at 02:00 charges the orders. Another at 02:15 ships them, set fifteen minutes later because that's usually lon…
Model Context Protocol with Spring AI, Building MCP Clients and Servers in Java
Model Context Protocol with Spring AI: Building MCP Clients and Servers in Java In the previous article, we explored how to build AI agents with Spr…
Replacing Basic Auth with JWT and OAuth2 in Spring Security
Basic auth was always the placeholder. It worked, but sending credentials on every single request never sat right — no real session, no expiry, no w…
One Missing WHERE Clause Can Expose Another Customer’s Data
A customer opens their dashboard and sees another company’s invoices. Nobody needed to break in. An endpoint returned data it should never have retu…
Reclazz: free, open-source hot reload for Spring Boot and SAP Commerce (no restart)
If you work on Spring Boot or SAP Commerce (Hybris), you know the tax: change one line, wait for a context restart or, on Hybris, an ant clean all a…
The Modular Layer JasperReports’ Powerful Engine Was Missing. Part 1: Where Jasper Came From and Why It Lacked Modularity
Researching such big and complex products as JasperReports, and even more building your own practical tool for it, is clearly not a trend of 2026. T…