Notes

SQLite is an embedded database that holds a SQL database in a single file. It is one of the most frequently chosen options for local storage in desktop and mobile apps.

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cmd.exe is the command processor on Windows NT-family systems. It debuted in 1993 with Windows NT 3.1 and ships with every Windows release. Since PowerShell arrived, cmd's role as an entry point for new code has shrunk,…

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iOS app builds go through similar steps to Android (compile → bundle resources → sign → package), but the tools, distribution channels, and policies look quite different. The biggest difference is that macOS and the App…

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The trend of running large language models directly on personal computers has taken hold rapidly since 2023. Where there used to be only cloud APIs, the combination of quantization formats like GGUF, inference runtimes…

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Even with the same language and the same code, the basics like paths, line endings, shells, and permissions shift once the operating system changes. Linux falls on the macOS side of this split (both are Unix-flavored).

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Most of AWS lives in magical data centers across the internet, charging money to do work. To verify on a developer machine, three costs apply daily: (1) creating a PoC account on real AWS, (2) paying somewhere, (3) stal…

Some external SaaS providers have no emulator: OAuth login · payments · dynamic DNS · Slack Webhook · AI providers, plus services where the official side never built one, such as Firebase Cloud Messaging. When you want…

When programs exchange data with each other they need an agreed-upon notation. The four we meet most often in config files, API responses, CI workflows, and environment variables are JSON, YAML, TOML, and XML.

JWT is a lightweight way to carry claims, but it does not by itself answer every question an authentication system needs. We cover the short-access-token / long-refresh-token pattern, invalidation strategies, algorithm…

The Agent Development Kit (ADK) Google released in 2025 is an open-source framework for building LLM-based agents and multi-agent systems. It assumes integration with Vertex AI but stays relatively neutral on models and…

Developing on Windows often runs into "Linux-only tools" — Docker, certain CLIs, shell scripts, compilation environments. WSL2 raises a real Linux environment inside the same machine without dual-booting or a heavyweigh…

Testing code that depends on external systems like a DB, Redis, or Kafka usually splits into two paths. We either mock the dependency, or we boot a real instance and verify against it. Testcontainers is the library that…

Storing passwords in plaintext is obviously wrong, but the choice of hash function and how to use it has changed across eras. The MD5 → SHA-1 → bcrypt → scrypt → Argon2 progression is not fashion but the result of an ar…

The question "OOP or functional?" used to be treated like a tribal feud. Today's modern languages support both, and real-world code mixes the two paradigms naturally. This article covers the origin of each paradigm, the…

Distributing traffic across backends, removing dead servers, and managing certificates from a single place are common needs across nearly every web service. AWS's seat for this is ELB (Elastic Load Balancing) — four fla…

A repository hosts documents for two kinds of readers: humans, and code-assistant agents (LLM-based IDE assistants and AI coders). This article covers the standards and conventions for both.

As LLM-based code assistants become routine, "how should we mark that AI helped?" has split into different team decisions. This article objectively organizes the relevant facts (lawsuits, OSS license positions, commit t…

The Model Context Protocol (MCP) is a protocol for connecting LLM clients to external data, tools, and prompts in a standardized way. Anthropic released it in November 2024 and other AI tools and IDEs adopted it quickly…

When running several containers on a single host (web, DB, cache, queue) Compose is the lightest path. One YAML file ties together dependencies, networks, volumes, and healthchecks. Not being a full orchestrator is both…

RAG (Retrieval-Augmented Generation) is an approach to supplement an LLM's limited training cutoff and memory limits with external knowledge. By separating retrieval and generation, you can handle new material without r…

After variables and functions, data structures are the next topic you meet most often when starting out in programming. The simplicity and speed of code shifts dramatically depending on which container you choose for th…

The word "observability" tends to suggest rolling out a full stack, but introducing a full stack from a small system makes operational cost outpace value pretty quickly.

Operating a relational DB directly is an area heavy with backup, recovery, HA, tuning, and version upgrades. RDS (Relational Database Service) takes a large share of those operational responsibilities off the user's han…

EC2 (Elastic Compute Cloud) is the first compute service AWS released, and it popularized the cloud "virtual machine" abstraction. As managed services have grown, the share of direct usage has diversified, but EC2 remai…

DNS, which resolves domain names to IPs, is one of the oldest pieces of internet infrastructure. AWS's managed DNS service is Route 53 — named after the standard DNS port (53).