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

Understand pdf file structure object streams, xref tables, and content streams—and why merging PDFs requires real parsing, not concatenation.

General

PDF File Structure Object Streams Explained: Why Merging PDFs Is Hard (2026)

Understand pdf file structure object streams, xref tables, and content streams—and why merging PDFs requires real parsing, not concatenation.

Unix timestamp timezone conversion DST explained: why 2:00 AM happens twice in November, and how UTC timestamps solve the ambiguity your code gets wrong.

General

Unix Timestamp Timezone Conversion DST: What Actually Happens When Clocks Fall Back

Unix timestamp timezone conversion DST explained: why 2:00 AM happens twice in November, and how UTC timestamps solve the ambiguity your code gets wrong.

Learn how application x-www-form-urlencoded vs multipart form-data actually work, when each breaks down, and which to use for files, binary data, and nested payloads.

General

application/x-www-form-urlencoded vs multipart/form-data: What's Actually on the Wire

Learn how application x-www-form-urlencoded vs multipart form-data actually work, when each breaks down, and which to use for files, binary data, and nested payloads.