Blog
Guides and how-tos on DNS, image formats, encoding, password security, data formats and web tools.
What Is a UUID? Versions, Uniqueness and When to Use One
What UUIDs are, how version 4 and version 7 differ, how unique they really are, and the trade-offs of using them as database keys.
How to Find the Domain Name Behind an IP Address
Turn an IP address into a hostname with a reverse DNS (PTR) lookup, online or with nslookup and dig. Learn how to read the result, why many IPs show a hosting company or no name at all, and which lookup to use when you want the owner or the website instead.
How to Check MX Records (and Fix Email That Isn't Arriving)
See any domain's MX records in seconds, online or with nslookup and dig, learn to read the priority numbers, and work through the checks that find out why email is not arriving.
What Is GZIP Compression, and Is It Working on Your Site?
How GZIP and Brotli compression make pages load faster, what should and should not be compressed, how to switch it on, and how to check it is working.
Which AI Crawlers Do the Top 1,000 Websites Block? (robots.txt Study, October 2026)
We read the robots.txt files of the 1,000 most popular websites: 20.9% block at least one of 16 AI bots. Per-bot shares, site strategies, common mistakes and open data.
How to Make a QR Code That Actually Scans: Size, Contrast and Testing
Practical rules for creating QR codes that scan first time, in print and on screen: what to encode, how big to print, colours, quiet zones and testing.
Unix Timestamps Explained: Epoch Time for Humans
What a Unix timestamp is, why it counts from 1970, seconds vs milliseconds, time zones, the year 2038 problem, and how to convert timestamps quickly.
How to Fix Invalid JSON: The 8 Most Common Errors
Trailing commas, single quotes, unquoted keys and the other mistakes that break JSON, with before-and-after examples and a quick way to find the problem.
