Ranjan Kumar
AI & ML Engineer · Author · Educator
I help AI builders design, build, and ship production-grade AI systems that actually work, cost-effectively, through hands-on writing, books, and practical engineering guidance.
Latest Posts
View all →FastAPI + LangGraph: What a Client Disconnect Commits
Your handler's shape, not your checkpointer, decides whether an interrupted agent run stops, finishes, or leaves a charge nobody recorded.
ai_mlThe ChatML Handbook, Second Edition: What Won and What Fragmented
The role-tagged message list became the universal format. The specific tokens did not. The second edition says so in the preface, and rebuilds the practical half around a support bot that actually runs.
ai_mlChatML: What It Is, Why OpenAI Removed It, What Replaced It
The spec was deleted in 2023. Qwen still ships the tokens, four papers since 2025 weaponise them, and the format your model expects was never a choice you got to make.
ai-engineeringLangGraph Names the Guarantee, Not the Unit
Seven parts of measurement found one recurring shape: the bound is real, it is correctly enforced, and it is scoped to something you did not assume.
My Books
The ChatML (Chat Markup Language) Handbook
A Developer’s Guide to Structured Prompting and LLM Conversations
Learn how to structure prompts using ChatML for predictable, production-ready LLM behavior.
Building Real-World Agentic AI Systems with LangGraph
Designing, building, evaluating, and shipping stateful, durable, multi-agent systems on LangGraph 1.x
A practitioner's guide to designing, deploying, and operating reliable agentic AI systems in the real world.
The Chat Templates Handbook
A Developer’s Guide to Jinja, apply_chat_template, and Rendering Model-Ready Prompts
A curated collection of battle-tested templates for common LLM tasks and workflows.
My Toolkit
A collection of tools I've built to boost productivity and simplify workflows.
Developer & AI Tools
Test Your Knowledge
Quiz yourself on AI engineering, observability, and production LLM systems
MedhaV - मेधावी
Start every day with clarity
Imagelly
AI-Based SaaS Image Edit/Enhancement Tool
Mermaid Diagram Generator
Create flowcharts, sequence diagrams, and more
MermAniSt — Mermaid Animation Studio
Turn Mermaid diagrams into animated presentations
LinkedIn Text Formatter
Format your LinkedIn posts with bold, italic, and more
MarkMelon: Markdown Editor
Edit, generate docs from Markdown and more
Slides Creator from Markdown
Generate beautiful presentations from Markdown
What I Write About
AI & ML Engineering
Production-ready AI systems, LLMs, and machine learning deployment strategies.
System Design
Scalable architectures, distributed systems, and infrastructure for AI applications.
Real-World Projects
Case studies, lessons learned, and practical insights from production deployments.
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