Blog
Guides and explainers for developers — written by the team behind NullTools.
What Is a Unix Timestamp and How Do You Use It?
Understand epoch time, why developers store timestamps as numbers, and how to convert them in JavaScript, Python and PHP.
A Practical Introduction to Regular Expressions
Learn the core building blocks of regular expressions, common patterns, and how to test them without guesswork.
How to Format, Validate and Debug JSON Like a Pro
Learn what JSON formatting is, why it matters, and how to pretty-print and validate JSON in JavaScript, Python and PHP.
MD5, SHA-1 and SHA-256 — Which Hash Should You Use?
What hashing is, how the common algorithms differ, and when each one is or is not appropriate.
How JSON Web Tokens (JWT) Work — and What They Do Not Do
A practical breakdown of JWT structure, decoding versus verification, and why you should never trust a token just because it looks valid.
What Is URL Encoding (Percent-Encoding)?
Why URLs need percent-encoding, which characters must be escaped, and how encodeURIComponent differs from encodeURI.
What Is Base64 and When Should You Actually Use It?
A plain-English walkthrough of Base64 encoding — what it is, why it exists, and the common cases where it helps versus hurts.
PNG vs JPEG vs WebP — Which Image Format Should You Use?
A practical guide to choosing between PNG, JPEG and WebP based on transparency, quality and file size.
UUID v4 vs ULID — Which Identifier Should You Use?
A practical comparison of UUID and ULID identifiers, covering randomness, sortability, readability and when to choose each one.
Why NullTools Runs Entirely in Your Browser
The privacy and speed reasons behind building developer tools that process everything locally instead of on a server.
HEX, RGB and HSL — How Color Codes Work
Understand the three most common ways to describe color on the web, and how to convert between them.
A Quick Markdown Syntax Guide
The essential Markdown syntax for headings, links, lists, code and more, with a live-preview mindset.
How to Compress Images Without Uploading Them
A practical guide to shrinking JPEG, PNG and WebP images locally, including when each format performs best.
How to Convert Between CSV and JSON
The differences between CSV and JSON, when to use each format, and how to convert between them in JavaScript, Python and PHP.
How to Create Strong Passwords (and Why Length Matters)
What actually makes a password strong, how to generate one securely, and the mistakes that make passwords weak.
How QR Codes Work (and How Much Data They Can Hold)
What QR codes are, how they store data, and the difference between static and dynamic codes.
How to Convert Images to PDF and PDF to Images Locally
The practical reasons to convert between images and PDF, and how to do it without uploading your files.
How Text Diff and Comparison Tools Work
The idea behind line-by-line diffing, and how to compare text or files programmatically.
Binary, Octal, Decimal and Hex — How Number Bases Work
Understand positional number systems and convert between bases using JavaScript, Python and PHP.
What Are HTML Entities and When Do You Need Them?
How named and numeric HTML entities work, and how to escape or unescape text in JavaScript, Python and PHP.