Official portfolio of S.M. Obaydur Rahman (Obaydur Rahman, Shimanto Rehman) — full-stack software developer, IEEE QPAIN 2026 researcher, backend & middleware engineer at Mutual Trust Bank, fintech APIs, AI automation, and data science in Dhaka, Bangladesh.https://obaydur.vercel.app/en-ushttps://obaydur.vercel.app/blog/dotnet-dispute-automation/https://obaydur.vercel.app/blog/dotnet-dispute-automation/A production-grade .NET 9 Web API for utility-bill disputes — layered architecture, repository + service-invoker patterns, two-level logging, and a step-by-step partner onboarding flow.Thu, 30 Apr 2026 00:00:00 GMThttps://obaydur.vercel.app/blog/fintech-payment-integration/https://obaydur.vercel.app/blog/fintech-payment-integration/The full integration lifecycle — partnership onboarding, IP whitelisting, payer-type classification, routing, reconciliation, and OTC agent networks — from inside the payments aisle of a tier-1 bank.Thu, 30 Apr 2026 00:00:00 GMThttps://obaydur.vercel.app/blog/payment-apis-architecture/https://obaydur.vercel.app/blog/payment-apis-architecture/Notes on production-grade payment REST APIs — token authentication, two-phase commit, bill locking, idempotency keys, and the dispute-resolution patterns that actually hold up in audit.Thu, 30 Apr 2026 00:00:00 GMThttps://obaydur.vercel.app/blog/hybrid-deep-learning-solar/https://obaydur.vercel.app/blog/hybrid-deep-learning-solar/A stacked ensemble combining Random Forest, XGBoost, Gradient Boosting, AdaBoost and a Neural Network meta-learner reaches ~95% accuracy on Bangladesh solar-irradiance data.Fri, 12 Dec 2025 00:00:00 GMThttps://obaydur.vercel.app/blog/ecommerce-sales-time-series/https://obaydur.vercel.app/blog/ecommerce-sales-time-series/A deep dive into seasonal patterns and predictive modeling for online retail sales using Python and statistical methods including ARIMA.Fri, 15 Nov 2024 00:00:00 GMThttps://obaydur.vercel.app/blog/ml-algorithm-comparison/https://obaydur.vercel.app/blog/ml-algorithm-comparison/Comprehensive evaluation of five ML algorithms on a customer-churn classification problem — comparing accuracy, precision, recall, and computational efficiency.Mon, 28 Oct 2024 00:00:00 GMThttps://obaydur.vercel.app/blog/data-pipeline-etl-airflow/https://obaydur.vercel.app/blog/data-pipeline-etl-airflow/Designing and implementing a robust data pipeline using Apache Airflow — handling millions of records daily with error handling, retries, and monitoring.Sun, 22 Sep 2024 00:00:00 GMThttps://obaydur.vercel.app/blog/deep-learning-image-classification/https://obaydur.vercel.app/blog/deep-learning-image-classification/Building and training a convolutional neural network using TensorFlow and Keras to classify images with 95 %+ accuracy on CIFAR-10.Sun, 18 Aug 2024 00:00:00 GMThttps://obaydur.vercel.app/blog/sql-query-optimization/https://obaydur.vercel.app/blog/sql-query-optimization/Analyzing a 45-second reporting query in production and implementing indexing, materialized views, and query rewriting to cut execution time to 4.2 seconds.Wed, 10 Jul 2024 00:00:00 GMThttps://obaydur.vercel.app/blog/ab-testing-statistical-analysis/https://obaydur.vercel.app/blog/ab-testing-statistical-analysis/Designing and analyzing A/B tests for website conversion rates, using proper statistical methods to ensure reliable, actionable results.Wed, 05 Jun 2024 00:00:00 GMThttps://obaydur.vercel.app/blog/realtime-analytics-dashboard-react/https://obaydur.vercel.app/blog/realtime-analytics-dashboard-react/Creating an interactive dashboard to visualize real-time data streams — WebSocket connections, dynamic chart updates, and TimescaleDB for time-series storage.Mon, 20 May 2024 00:00:00 GMThttps://obaydur.vercel.app/blog/postgresql-beginners-guide/https://obaydur.vercel.app/blog/postgresql-beginners-guide/A practical walkthrough of PostgreSQL installation, your first database, table creation, basic queries, and essential administration tasks.Fri, 12 Apr 2024 00:00:00 GMThttps://obaydur.vercel.app/blog/database-indexes-performance/https://obaydur.vercel.app/blog/database-indexes-performance/How database indexes work, when to use them, the different types available in PostgreSQL, and how they can dramatically improve query performance.Mon, 25 Mar 2024 00:00:00 GMThttps://obaydur.vercel.app/blog/database-backup-recovery/https://obaydur.vercel.app/blog/database-backup-recovery/Essential backup and recovery techniques every database administrator should know to protect critical data — including full, incremental, and continuous backup approaches.Sun, 18 Feb 2024 00:00:00 GMThttps://obaydur.vercel.app/blog/git-version-control-beginners/https://obaydur.vercel.app/blog/git-version-control-beginners/Learn the fundamentals of Git — from basic commands and branching to working with remote repositories and common workflows.Mon, 15 Jan 2024 00:00:00 GMThttps://obaydur.vercel.app/blog/git-advanced-branching-strategies/https://obaydur.vercel.app/blog/git-advanced-branching-strategies/Master advanced Git techniques including Git Flow, rebasing vs merging, stashing, conflict resolution, and effective team collaboration patterns.Sun, 10 Dec 2023 00:00:00 GMThttps://obaydur.vercel.app/blog/codeigniter-installation-guide/https://obaydur.vercel.app/blog/codeigniter-installation-guide/Step-by-step guide to installing and configuring CodeIgniter 4 — from Composer to your first controller, view, and route in under 30 minutes.Sun, 05 Nov 2023 00:00:00 GMThttps://obaydur.vercel.app/blog/why-codeigniter-php-developers/https://obaydur.vercel.app/blog/why-codeigniter-php-developers/A deep look at the advantages of CodeIgniter for PHP development — rapid development, MVC architecture, security features, and how it compares to alternatives.Fri, 20 Oct 2023 00:00:00 GMThttps://obaydur.vercel.app/blog/covid-sentiment-bangladesh/https://obaydur.vercel.app/blog/covid-sentiment-bangladesh/Classical ML, ensemble classification and LSTM with Word2Vec embeddings applied to Bengali / English-mixed social-media chatter — best 78.8% accuracy.Sat, 04 Mar 2023 00:00:00 GMT