Tool	Best when you need…	Check before relying on the result
JSON Formatter	API responses, configuration snippets and copied JSON that is difficult to read on one line.	Validate that strings, numbers and booleans still have the expected types.
Base64 Encode/Decode	Inspecting API payload fragments, data URIs, small configuration values and learning how Base64 representation works.	Decode a sample to verify a round trip.
Hash Generator	Checksums, development workflows, examples and verifying that two identical text inputs produce the same digest.	Confirm the same algorithm and text encoding are used on both sides.
Color Picker	Front-end styling, quick mockups and translating a chosen color between common web formats.	Check foreground/background contrast separately.
Percentage Calculator	Discounts, growth rates, markups, score changes and “what percent is X of Y?” calculations.	Write down the original/reference value before calculating change.
Age Calculator	Everyday age checks, forms and understanding the difference between calendar age and a simple day-count approximation.	Check day/month order when copying dates from another locale.
EMI / Loan Calculator	Comparing loan scenarios before speaking with a lender or checking whether a quoted payment is in the expected range.	Compare total repayment as well as monthly EMI.
Unit Converter	Everyday dimensions, DIY, travel, forms and quick cross-system checks.	Keep enough decimal places for the task.

Dev & Calc Tools

Developer