Master Essential Web Utilities

In-depth Guides & Tutorials from Kestrel Tools. Unlock the full potential of developer tools with expert insights, practical tutorials, and tips.

Explore Kestrel Tools Read Latest Articles

Latest Insights

Kestrel Tools Base64 Encoder showing café and an emoji encoded correctly using the modern TextEncoder pattern

engineering

Why `btoa("café")` Throws (And How to Base64-Encode Unicode the Right Way)

btoa unicode javascript fails on accents and emoji because btoa assumes Latin-1. Here's the modern TextEncoder fix, with copy-paste code and roundtrip tests.

Kestrel Tools JWT Decoder showing a decoded token's header, payload, and signature side by side with a 'signature not verified' warning

developer-tools

JWT Decoder vs Token Introspection: When 'I Read the Token' Isn't 'I Trusted It'

JWT decoder vs token introspection: decoding a JWT proves nothing about trust. Here's when to validate, when to introspect, and when reading is enough.

Kestrel Tools JSON Formatter showing a 19-digit ID rounded by JavaScript's IEEE 754 number type

engineering

What's Actually Inside Your JSON Numbers? (Why Big IDs Lose Precision)

JSON number precision in JavaScript silently rounds IDs above 9,007,199,254,740,991. Here's why, how to spot it, and the fixes that actually work in 2026.