Engineering leader and coach. I lead with clarity, help teams get more out of AI, and coach engineers early in their careers.https://karthiksubramanian.dev/https://karthiksubramanian.dev/writing/stop-testing-your-ai-start-measuring-it/https://karthiksubramanian.dev/writing/stop-testing-your-ai-start-measuring-it/Unit-test thinking breaks down for LLM features. How I measured an AI-generated training simulator instead, by simulating players and ranking models.Sun, 14 Jun 2026 13:15:03 GMThttps://karthiksubramanian.dev/writing/the-setup-is-the-strategy/https://karthiksubramanian.dev/writing/the-setup-is-the-strategy/How I set up Claude Code to carry a product migration across four repositories: the planning, the development loop, the review process and what it cost.Thu, 16 Apr 2026 13:49:55 GMThttps://karthiksubramanian.dev/writing/knight-to-h3-making-chess-feel-alive-with-amazon-nova/https://karthiksubramanian.dev/writing/knight-to-h3-making-chess-feel-alive-with-amazon-nova/A 3D chess game where adventurers clash with Skeleton Warriors, and an AI mentor powered by Amazon Nova teaches you to play.Tue, 10 Feb 2026 15:50:54 GMThttps://karthiksubramanian.dev/writing/navigating-aws-neptune-graph-with-ai/https://karthiksubramanian.dev/writing/navigating-aws-neptune-graph-with-ai/Building an AI agent with Strands that queries an Amazon Neptune graph in plain English, and handles results too large for the model's context.Fri, 03 Oct 2025 03:08:16 GMThttps://karthiksubramanian.dev/writing/chat-with-my-digital-twin/https://karthiksubramanian.dev/writing/chat-with-my-digital-twin/My AWS Builder Challenge entry: a personal website on the AWS Free Tier with a chatbot that runs in the browser on Chrome's built-in AI.Fri, 03 Oct 2025 01:06:30 GMThttps://karthiksubramanian.dev/writing/building-a-multiplayer-triviasnake-game-with-amazon-q-developer/https://karthiksubramanian.dev/writing/building-a-multiplayer-triviasnake-game-with-amazon-q-developer/How far Amazon Q Developer could carry a full build: a multiplayer snake game with trivia questions on serverless AWS, made in about a dozen hours.Sat, 21 Jun 2025 20:24:15 GMThttps://karthiksubramanian.dev/writing/rapid-learnings-from-rapid-prototyping/https://karthiksubramanian.dev/writing/rapid-learnings-from-rapid-prototyping/What started as a one-day AI prototype became a week of lessons about building fast, designing for users and the practical side of AI features.Sun, 15 Jun 2025 11:11:04 GMThttps://karthiksubramanian.dev/writing/building-a-real-time-ai-tutoring-assistant/https://karthiksubramanian.dev/writing/building-a-real-time-ai-tutoring-assistant/How to build an AI assistant that notices when a student is struggling and offers help in real time: the architecture, core components and prompts.Sun, 15 Jun 2025 10:10:17 GMThttps://karthiksubramanian.dev/writing/partyrock-with-bedrock/https://karthiksubramanian.dev/writing/partyrock-with-bedrock/A first look at PartyRock, AWS's playground for building small generative AI apps without code, and the trip planner I built with it.Thu, 16 Nov 2023 17:56:37 GMThttps://karthiksubramanian.dev/writing/the-kinesis-analytics-apache-flink-playlist/https://karthiksubramanian.dev/writing/the-kinesis-analytics-apache-flink-playlist/My videos and notes on stream processing with Apache Flink and Kinesis Data Analytics, from a few years of building with them.Tue, 15 Aug 2023 06:44:32 GMThttps://karthiksubramanian.dev/writing/aws-lambda-ecr-nuances/https://karthiksubramanian.dev/writing/aws-lambda-ecr-nuances/Part 7 of the serverless series: two surprises from running Lambda functions as container images, ephemeral storage and ECR image cleanup.Thu, 22 Sep 2022 13:56:00 GMThttps://karthiksubramanian.dev/writing/downloading-a-file-from-s3-using-api-gateway-aws-lambda/https://karthiksubramanian.dev/writing/downloading-a-file-from-s3-using-api-gateway-aws-lambda/Part 6 of the serverless series: an endpoint that returns a request's status and a time-limited download link for its CSV in S3.Thu, 22 Sep 2022 13:55:00 GMThttps://karthiksubramanian.dev/writing/writing-a-csv-to-s3-from-aws-lambda/https://karthiksubramanian.dev/writing/writing-a-csv-to-s3-from-aws-lambda/Part 5 of the serverless series: turning the scraped results into a CSV file and saving it to S3 from Lambda.Thu, 22 Sep 2022 13:54:00 GMThttps://karthiksubramanian.dev/writing/web-scraping-with-selenium-aws-lambda/https://karthiksubramanian.dev/writing/web-scraping-with-selenium-aws-lambda/Part 4 of the serverless series: a second Lambda that reads requests from the SQS queue and scrapes the page with Selenium.Thu, 22 Sep 2022 13:53:00 GMThttps://karthiksubramanian.dev/writing/storing-aws-sqs-messages-to-dynamodb-with-aws-lambda/https://karthiksubramanian.dev/writing/storing-aws-sqs-messages-to-dynamodb-with-aws-lambda/Part 3 of the serverless series: saving each request to DynamoDB and sending it to an SQS queue for processing, all defined in the SAM template.Thu, 22 Sep 2022 13:52:00 GMThttps://karthiksubramanian.dev/writing/building-a-rest-api-with-aws-api-gateway-lambda/https://karthiksubramanian.dev/writing/building-a-rest-api-with-aws-api-gateway-lambda/Part 2 of the serverless series: an API Gateway endpoint backed by a Python Lambda that accepts requests, built and deployed with the SAM CLI.Thu, 22 Sep 2022 13:51:00 GMThttps://karthiksubramanian.dev/writing/aws-serverless-architecture-with-sam/https://karthiksubramanian.dev/writing/aws-serverless-architecture-with-sam/Part 1 of a series on a serverless scraping backend: the overall architecture, setting up the SAM CLI and deploying the first stack to AWS.Thu, 22 Sep 2022 13:50:00 GMThttps://karthiksubramanian.dev/writing/hosting-api-documentation-with-postman-springboot/https://karthiksubramanian.dev/writing/hosting-api-documentation-with-postman-springboot/Generating HTML API docs from a Postman collection on every build, and serving them from the Spring Boot app itself so they stay inside your network.Sun, 09 Aug 2020 17:43:12 GMT