SQL

PortSwigger Web Security Academy offers free online training and interactive labs for web application security.

Aito is a predictive database that serves calibrated predictions from live data in a query.

CS50x is Harvard’s introduction to computer science and programming for students with or without prior experience.

RegexLearn teaches regular expressions through interactive lessons and practice at different levels.

Apache Flink performs stateful computations on data streams for stream processing applications.

Build blogs, presentations, and online stores with Vvveb, an open-source content management system and drag-and-drop site builder.

Mockaroo generates custom test datasets in CSV, JSON, SQL, and Excel formats, with an API mocking tool for software testing.

backend-challenges lists open-source coding challenges based on real job requirements.

Programiz offers free online compilers and code editors alongside programming tutorials for languages including Python, JavaScript, SQL, and C++.

Mage automates production data pipelines with SQL and Python workflows, data-quality checks, failure recovery, and performance tuning.

StudyLion is a Discord bot that tracks study time and provides to-do lists, Pomodoro timers and reminders.

TutorialKart collects online courses, learning materials, and interview questions across programming, databases, SAP, and other subjects.

PostgreSQL vector search can use pgvecto.rs, an extension described as scalable and low latency.

Rivestack provides managed PostgreSQL with pgvector on NVMe for AI vector search.

Tallinn's open data API supports queries for dataset tables, selected columns, filters, ordering, and paginated results.

Tony Hudson’s site includes technical posts, including a guide to installing software described in a recent article.

CodeAnalogies teaches CSS and JavaScript concepts through visual guides, analogies, and imagery.

Data Engineer Handbook collects links and resources for data engineering.

Zerve supports research and analytics workflows, with AI agents for data discovery, analysis, reports and production deployment.

For data engineering and business intelligence practitioners, The Data Engineering Show podcast discusses practical data challenges.

CS50’s Python course introduces programming with Python, covering code reading and writing, testing, debugging, and core concepts.

Refraction uses AI to refactor code, generate documentation, and create unit tests from code samples.

Apache Spark is a unified engine for large-scale data processing and analytics.

SemanticDiff provides language-aware diffs for reviewing GitHub commits and pull requests.