React Interview Question: What Is the Virtual DOM and Reconciliation?
Short answer: when state changes, React calls your components to produce a new tree of plain JavaScript objects describing the UI (often cal...
Free tutorials & developer tools
Tech concepts, explained simply.
Clear, practical tutorials on PHP, Laravel, MySQL, JavaScript, Vue JS, Angular, REST APIs, Git and more — plus handy tools to speed up your everyday development work.
Animated examples of SQL, Laravel, PHP and JavaScript code being written and run, from Technical Simple tutorials.
0:00 / 1:00
Fresh from the blog
Latest articles
SQL Interview Question: WHERE vs HAVING
Short answer: WHERE filters individual rows before grouping. HAVING filters groups after GROUP BY , so it can use aggregate functions like C...
System Design Interview Question: How Should You Approach a Design Problem?
System design interviews are open-ended on purpose. Interviewers want to see structured thinking and trade-off reasoning more than a "correc...
Streaming LLM Responses to the Browser with Server-Sent Events
Long answers can take many seconds to generate. Streaming shows text as it is produced, so users see progress immediately instead of staring...
Free utilities
Developer tools
Quick tools that run in your browser — nothing to install.
HTML Editor
Write HTML and preview it live, with formatting, import and export.
Open toolJSON Formatter
Format, validate, minify and sort JSON with exact error positions.
Open toolRegex Tester
Test regular expressions with live highlighting and capture groups.
Open toolCase Converter
Convert text to UPPER, lower, Title, Sentence and more in one click.
Open toolBase64 Encoder
Encode and decode Base64 with full Unicode and URL-safe support.
Open toolJWT Decoder
Inspect a JSON Web Token’s header, payload and expiry.
Open toolCron Helper
Explain cron schedules in plain English and see the next runs.
Open toolHash Generator
Generate MD5, SHA, PBKDF2 and Bcrypt hashes right in your browser.
Open toolTodo List
A simple, private task list that remembers your work between visits.
Open toolNever miss a new tutorial
Join the newsletter and get new articles delivered to your inbox. Free, and you can unsubscribe anytime.