Latest
63

WebP vs PNG vs JPEG: which format for which image
How the three main web image formats actually differ, what each costs in bytes, and a decision rule you can apply without thinking about it.
2 min readAug 29, 2026
WHOIS is dead and RDAP replaced it: what changed
Why WHOIS returns less than it used to, what RDAP gives you instead, and how to read registrar status codes like clientTransferProhibited.
4 min readAug 29, 2026
XML sitemaps: what to include, and how to split them
How sitemaps actually affect indexing, which URLs belong in one, when to split into multiple files, and how to use them to diagnose coverage problems.
3 min readAug 29, 2026
What this blog covers
This is a working blog rather than a content marketing programme. The guides come out of building a verification product: checking domain records, reading analytics connections, parsing payment data, and keeping a Next.js site indexed while doing it. Each one exists because we needed the answer and the available answers were vague.
The writing is organised into hubs - technical SEO, developer reference, links and authority, tracking and analytics, images and page weight, launching, SaaS metrics, domains and infrastructure, and everyday converters and reference. Each hub has a pillar guide that covers the subject end to end and shorter pieces that go deep on one question, and every piece links to the tools that do the job it describes.
Where a claim is contested, we say which way the evidence points and how strong it is rather than picking the more confident-sounding version. A lot of widely repeated SEO advice is either outdated, true but too small to matter, or an artefact of correlation, and saying so is more useful than adding another confident post to the pile.
Guides are dated and updated in place rather than reposted. If something here is wrong or has gone stale, the correction goes into the original page with the updated date changed, so a link you saved keeps pointing at the current version.
Common questions
- Is this blog about RankCert?
- Rarely. Most of it is general-purpose technical writing about SEO, domains, analytics and metrics that applies wherever you ship. Product news lives in the changelog.
- Can I republish or quote these guides?
- Quote freely with a link. Full republication is not permitted, mostly because the guides get corrected in place and copies do not.