TeachyLeaf
Free browser-based tool
Format SQL online
Beautify SQL with selectable dialect, indentation, and keyword case. The formatter changes layout, not query logic.
Open the SQL formatter
Programming and electronics resources
Learn technology through clear, practical examples.
Explore browser-based tools and practical lessons in SQL, Laravel, JSON, and electronics circuit theory.
Created by Amit Kumar Das · Meet the founder
Learn with purpose
A practical way to learn technical topics
Build understanding with focused explanations, examples you can follow, and tools that state their limits.
🔬
Start with the idea
Understand the core concept and the assumptions behind it before adding complexity.
💻
Follow a worked example
See sample inputs, expected results, and explanations that connect the steps to the outcome.
📚
Know what to trust
Check each tool's privacy and limitations, then verify examples in the environment where you plan to use them.
Build and check
Free browser-based developer tools
Format SQL and JSON, or explore a circuit calculation. Tool inputs stay in your browser.
Free browser-based tool
Format and validate JSON
Check JSON syntax, format valid data, and get readable parse errors. Your input stays in your browser.
Open the JSON formatter
Free browser-based tool
Encode or decode URL components
Convert text for use as one URL component, or decode percent-encoded text. The tool does not process a complete URL.
Open the URL encoder and decoder
Electronics · Circuit calculator
Explore a Thevenin equivalent
Adjust a loaded voltage divider and calculate its Thevenin voltage, resistance, load voltage, and load current.
Open the circuit calculatorLooking for a particular tool?
Explore all developer toolsLearn by example
Featured tutorials and guides
Explore a few practical starting points, then browse the full library for every published lesson.
SQL · Beginner
Start with SQL SELECT and WHERE
Choose columns, filter rows, sort the results, and compare your work with an expected output.
Read the SQL basics lesson
Laravel · Beginner
Follow a Laravel request from URL to response
Trace a real TeachyLeaf page through routing, middleware, a controller, and its Blade layout.
Read the Laravel request lifecycle lesson
JSON · Debugging guide
Find and fix common JSON syntax errors
See how missing commas, trailing commas, unquoted keys, and mismatched brackets make JSON invalid.
Read the JSON syntax guide
Electronics · Circuit theory
Thevenin’s theorem: simplify a circuit at its load
Find the equivalent voltage and resistance for a loaded voltage divider, then compare the calculated load values.
Read the Thevenin lessonWant to explore more lessons?
Browse all tutorials