Practical engineering insights on backend systems, system design, databases, infrastructure and AI engineering, for developers, architects and engineering leaders.https://varcore.dev/en-ushttps://varcore.dev/blog/node-js-from-zero-part-11-best-practices-for-production-ready-node-js/https://varcore.dev/blog/node-js-from-zero-part-11-best-practices-for-production-ready-node-js/The habits, tools and settings that turn a Node.js app that works on your laptop into a service you can run, debug and trust for years.Sat, 14 Nov 2026 09:37:10 GMTNode.jsNode.jsJavaScriptBackendhttps://varcore.dev/blog/node-js-from-zero-part-10-testing-with-the-built-in-test-runner/https://varcore.dev/blog/node-js-from-zero-part-10-testing-with-the-built-in-test-runner/Node.js ships with a fast, capable test runner. Here’s how to write unit tests, mocks, HTTP tests and coverage reports without installing…Sat, 14 Nov 2026 09:36:29 GMTNode.jsNode.jsJavaScriptBackendhttps://varcore.dev/blog/node-js-from-zero-part-9-worker-threads-child-processes-and-scaling-out/https://varcore.dev/blog/node-js-from-zero-part-9-worker-threads-child-processes-and-scaling-out/Node runs your code on one thread. Here’s how to handle CPU-heavy work and use every core with worker threads, child processes and multiple…Sat, 14 Nov 2026 09:35:51 GMTNode.jsNode.jsJavaScriptBackendhttps://varcore.dev/blog/node-js-from-zero-part-8-building-an-http-server-from-scratch/https://varcore.dev/blog/node-js-from-zero-part-8-building-an-http-server-from-scratch/Build a working JSON API with nothing but Node’s built-in http module, and learn exactly what frameworks do for you.Sat, 14 Nov 2026 09:35:10 GMTNode.jsNode.jsJavaScriptBackendhttps://varcore.dev/blog/node-js-from-zero-part-7-buffers-and-streams/https://varcore.dev/blog/node-js-from-zero-part-7-buffers-and-streams/How Node.js handles raw bytes, and how streams let you process gigabytes of data with a tiny, steady amount of memory.Sat, 14 Nov 2026 09:34:26 GMTNode.jsNode.jsJavaScriptBackendhttps://varcore.dev/blog/node-js-from-zero-part-6-files-paths-processes-and-environment/https://varcore.dev/blog/node-js-from-zero-part-6-files-paths-processes-and-environment/Working with the file system, paths, environment variables, command-line arguments and the process itself, the Node.js way.Sat, 14 Nov 2026 09:33:25 GMTNode.jsNode.jsJavaScriptBackendhttps://varcore.dev/blog/node-js-from-zero-part-5-error-handling-that-doesnt-crash-your-server/https://varcore.dev/blog/node-js-from-zero-part-5-error-handling-that-doesnt-crash-your-server/How errors flow through sync and async Node.js code, how to design good error types, and how to keep one bad request from taking down your…Sat, 14 Nov 2026 09:32:41 GMTNode.jsNode.jsJavaScriptBackendhttps://varcore.dev/blog/node-js-from-zero-part-4-the-event-loop-promises-and-async-await/https://varcore.dev/blog/node-js-from-zero-part-4-the-event-loop-promises-and-async-await/How Node.js handles thousands of things at once on a single thread, and how to write async code that’s fast and easy to read.Sat, 14 Nov 2026 09:32:03 GMTNode.jsNode.jsJavaScriptBackendhttps://varcore.dev/blog/node-js-from-zero-part-3-modules-npm-and-package-json/https://varcore.dev/blog/node-js-from-zero-part-3-modules-npm-and-package-json/How to split Node.js code into modules, how npm and package.json really work, and how to keep dependencies safe.Sat, 14 Nov 2026 09:31:26 GMTNode.jsNode.jsJavaScriptBackendhttps://varcore.dev/blog/node-js-from-zero-part-2-modern-javascript-you-need-for-node-js/https://varcore.dev/blog/node-js-from-zero-part-2-modern-javascript-you-need-for-node-js/The parts of modern JavaScript you’ll use in every Node.js file, explained with short examples you can run.Sat, 14 Nov 2026 09:30:51 GMTNode.jsNode.jsJavaScriptBackendhttps://varcore.dev/blog/node-js-from-zero-part-1-why-node-js-setting-it-up-and-your-first-script/https://varcore.dev/blog/node-js-from-zero-part-1-why-node-js-setting-it-up-and-your-first-script/What Node.js really is, why it runs so much of the web, and how to write and run your first script.Sat, 14 Nov 2026 09:30:01 GMTNode.jsNode.jsJavaScriptBackendhttps://varcore.dev/blog/go-from-zero-part-12-building-a-rest-api-with-the-standard-library/https://varcore.dev/blog/go-from-zero-part-12-building-a-rest-api-with-the-standard-library/Everything from the series in one place: a complete, tested JSON API with routing, validation, middleware, logging and graceful shutdown…Sat, 14 Nov 2026 04:13:40 GMTGolangGolangBackendhttps://varcore.dev/blog/go-from-zero-part-11-best-practices-for-production-ready-go/https://varcore.dev/blog/go-from-zero-part-11-best-practices-for-production-ready-go/The idioms, tools and habits that turn Go code that works into Go code you can run, debug and maintain for years.Sat, 14 Nov 2026 04:13:02 GMTGolangGolangBackendhttps://varcore.dev/blog/go-from-zero-part-10-testing-benchmarks-and-fuzzing/https://varcore.dev/blog/go-from-zero-part-10-testing-benchmarks-and-fuzzing/Go ships with everything you need to test your code. Here’s how to write tests people enjoy maintaining.Sat, 14 Nov 2026 04:12:17 GMTGolangGolangBackendhttps://varcore.dev/blog/go-from-zero-part-9-generics-without-the-headache/https://varcore.dev/blog/go-from-zero-part-9-generics-without-the-headache/Write a function once, use it with many types, and keep full type safety. Plus when not to use generics at all.Sat, 14 Nov 2026 04:11:09 GMTGolangGolangBackendhttps://varcore.dev/blog/go-from-zero-part-8-sync-context-and-concurrency-patterns/https://varcore.dev/blog/go-from-zero-part-8-sync-context-and-concurrency-patterns/Mutexes, WaitGroups, context cancellation, worker pools and pipelines: the concurrency toolkit you’ll use in real services.Fri, 13 Nov 2026 05:12:07 GMTGolangGolangBackendhttps://varcore.dev/blog/go-from-zero-part-7-goroutines-channels-and-select/https://varcore.dev/blog/go-from-zero-part-7-goroutines-channels-and-select/Go’s most famous feature, explained with simple pictures and runnable examples: doing many things at once, safely.Fri, 13 Nov 2026 05:10:10 GMTGolangGolangBackendhttps://varcore.dev/blog/go-from-zero-part-6-packages-modules-and-project-layout/https://varcore.dev/blog/go-from-zero-part-6-packages-modules-and-project-layout/How to split Go code into packages, manage dependencies with modules, and lay out a project that stays tidy as it grows.Fri, 13 Nov 2026 05:08:31 GMTGolangGolangBackendhttps://varcore.dev/blog/go-from-zero-part-5-error-handling-the-go-way/https://varcore.dev/blog/go-from-zero-part-5-error-handling-the-go-way/No exceptions, no try/catch. Just values you can inspect, wrap and handle on purpose. Here’s how to do it well.Fri, 13 Nov 2026 05:07:03 GMTGolangGolangBackendhttps://varcore.dev/blog/go-from-zero-part-4-methods-interfaces-and-composition/https://varcore.dev/blog/go-from-zero-part-4-methods-interfaces-and-composition/Go has no classes and no inheritance. Here’s what it gives you instead, and why many people end up preferring it.Fri, 13 Nov 2026 05:05:39 GMTGolangGolangBackendhttps://varcore.dev/blog/go-from-zero-part-3-arrays-slices-maps-and-structs/https://varcore.dev/blog/go-from-zero-part-3-arrays-slices-maps-and-structs/How Go stores collections of data, how slices really work under the hood, and the traps to avoid.Fri, 13 Nov 2026 05:04:03 GMTGolangGolangBackendhttps://varcore.dev/blog/go-from-zero-part-2-variables-types-control-flow-and-functions/https://varcore.dev/blog/go-from-zero-part-2-variables-types-control-flow-and-functions/The building blocks you’ll use in every Go file, explained with small examples you can run.Fri, 13 Nov 2026 05:02:40 GMTGolangGolangBackendhttps://varcore.dev/blog/go-from-zero-part-1-why-go-setting-it-up-and-your-first-program/https://varcore.dev/blog/go-from-zero-part-1-why-go-setting-it-up-and-your-first-program/What Go is, why so many teams pick it, and how to write, run and build your very first program.Fri, 13 Nov 2026 05:00:56 GMTGolangGolangBackendhttps://varcore.dev/blog/llm-seo-in-2026-a-technical-guide-to-getting-cited-by-ai-answer-engines/https://varcore.dev/blog/llm-seo-in-2026-a-technical-guide-to-getting-cited-by-ai-answer-engines/A few months ago I ran an experiment on a site I look after. I took twenty questions our customers actually ask, put each one into ChatGPT…Thu, 12 Nov 2026 11:31:01 GMTAI EngineeringLLMClaudeAI Toolinghttps://varcore.dev/blog/nats-dashboard-a-free-self-hosted-web-ui-for-nats-and-jetstream/https://varcore.dev/blog/nats-dashboard-a-free-self-hosted-web-ui-for-nats-and-jetstream/If you run NATS in production, you have probably juggled the nats CLI, raw /varz JSON and a Grafana board just to answer simple questions…Thu, 12 Nov 2026 10:45:12 GMTInfrastructure & DevOpsNATSMessagingSelf-Hostedhttps://varcore.dev/blog/claude-duet-explained-how-technical-people-should-use-anthropics-new-personal-ai-agent/https://varcore.dev/blog/claude-duet-explained-how-technical-people-should-use-anthropics-new-personal-ai-agent/It runs in the cloud, checks your apps every few hours, and messages you only when something needs your attention. Here is what it is, how…Thu, 12 Nov 2026 10:02:58 GMTAI EngineeringLLMClaudeAI Toolinghttps://varcore.dev/blog/starrocks-indexes-and-best-practices-part-2-n-gram-full-text-vector-and-verifying-index-usage/https://varcore.dev/blog/starrocks-indexes-and-best-practices-part-2-n-gram-full-text-vector-and-verifying-index-usage/Part 2 of 2: N-gram Bloom filter, full-text inverted index, vector index, and how to prove your index is actually used.Thu, 12 Nov 2026 05:58:18 GMTDatabasesStarRocksOLAPAnalyticshttps://varcore.dev/blog/starrocks-indexes-and-best-practices-part-1-sort-keys-prefix-bitmap-and-bloom-filter/https://varcore.dev/blog/starrocks-indexes-and-best-practices-part-1-sort-keys-prefix-bitmap-and-bloom-filter/Part 1 of 2: sort keys, the built-in indexes, and when to add Bitmap and Bloom filter indexes.Thu, 12 Nov 2026 05:57:06 GMTDatabasesStarRocksOLAPAnalyticshttps://varcore.dev/blog/how-to-use-claude-the-right-way-in-go-development-a-practical-playbook/https://varcore.dev/blog/how-to-use-claude-the-right-way-in-go-development-a-practical-playbook/A practical playbook for using Claude Code on real Go codebases, from project setup and gopls integration to prompts, tests and review.Thu, 12 Nov 2026 05:43:32 GMTAI EngineeringLLMClaudeAI Toolinghttps://varcore.dev/blog/why-starrocks-an-engineers-guide-to-choosing-it-for-real-time-and-lakehouse-analytics/https://varcore.dev/blog/why-starrocks-an-engineers-guide-to-choosing-it-for-real-time-and-lakehouse-analytics/One SQL engine for your dashboards, your fresh data and your Iceberg tables, and why that matters more than another benchmark chart.Thu, 12 Nov 2026 05:23:12 GMTDatabasesStarRocksOLAPAnalyticshttps://varcore.dev/blog/mongodb-indexes-a-practical-guide-to-faster-queries/https://varcore.dev/blog/mongodb-indexes-a-practical-guide-to-faster-queries/Why your queries are slow, and how the right index fixes themThu, 12 Nov 2026 04:52:55 GMTDatabasesMongoDBIndexing