635: quantum of sollazzo
#635: quantum of sollazzo – 9 December 2025
The data newsletter by @puntofisso.
Hello, regular readers and welcome new ones :) This is Quantum of Sollazzo, the newsletter about all things data. I am Giuseppe Sollazzo, or @puntofisso. I've been sending this newsletter since 2012 to be a summary of all the articles with or about data that captured my attention over the previous week. The newsletter is and will always (well, for as long as I can keep going!) be free, but you're welcome to become a friend via the links below.
Quantum #627 had an open rate of 50.1% and a click rate of 14.78%.
The most clicked link was ColorPalette.Pro.
PERSONAL NEWS KLAXON
As you might have seen on LinkedIn, in January I'll be joining HM Revenue & Customs as Deputy Director of Innovation Strategy. For those of you who don't know, HMRC is the United Kingdom's department working predominantly on tax collection, and I'll be leading its AI Accelerator focused on Enterprise Transformation.
I'm pretty excited. Thinking about my career, it looks like I keep swapping between open-ended innovation-related roles and those mostly focussed on running existing services (although the latter roles always have an aspect of transformation and innovation). So it's going to be pretty busy at the beginning of 2026, but I still hope to be able to write Quantum during the weekends as usual.
AMA – Ask Me Anything! Submit a question via this anonymous Google form. I'll select a few every 4-5 weeks and answer them on here :-) Don't be shy!
The Quantum of Sollazzo grove now has 35 trees. It helps managing this newsletter's carbon footprint. Check it out at Trees for Life.
'till next week,
Giuseppe @puntofisso.bsky.social
🛎️ Things that caught my attention
Switzerland keeps amazing me for its ability to share great open data, and visualize it, often via initiatives run by local administrations. In this application that my Zürich-based friend Ettore Ferranti sends me, data is used to generate a "4D" map of the city, showing its architectural development from the past through the present to the future. This is inspirational, and I'd love to see UK local authorities offering some of the same!
✨ Topical
Godless men, saintly daughters and finding yourself at 25 ⛪
Leo Benedictus looks at UK census data on religious habits, and makes the interesting analysis of gender differences. captured in the chart below.
From luxury to fast fashion: How green are European brands?
"DW and EDJNet investigated almost 500 sustainability claims to find which fashion companies keep their commitments, and which skirt the issue."
Kira Schacht reports.
Huh. Apparently cars don't have to kill people.
"This past summer, Helsinki made an astonishing announcement: as of August, the Finnish capital went an entire year without any traffic deaths."
The UK doesn't fare too badly, by the way.
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🛠️📖 Tools & Tutorials
FediMeteo: How a Tiny €4 FreeBSD VPS Became a Global Weather Service for Thousands
Aside from the subject matter, weather data, that is very interesting, this blog post also discusses how very often you don't need huge infrastructure to run solid, reliable, scalable services.
(via Luis Natera)
A modern guide to SQL JOINs
"There are many SQL JOINs guides and tutorials, but this one takes a different approach. We try to avoid misleading wording and imagery, and we structure the material in a different way. The goal of this article is to clarify your mental model."
FLOWSQL
"FlowSQL is a free, privacy-focused SQL editor that runs entirely in your browser. You can write and execute SQL queries, import CSV files, and work with SQLite databases - all without sending any data to a server."
Project Wallace
"Project Wallace is a set of CSS analyzers that check your complexity, specificity, performance, Design Tokens and much more. And all of that in a single web app."
A5 Grid System
"A5 is a geospatial index that partitions the world into pentagonal cells. The cells are available at 31 different resolution levels, with the largest cell covering the whole world, and the smallest less than 30mm². Within each resolution level the cells have equal area, as per the OGC definition."
Obviously you've heard about rectangles and squares (including a famous three word based services), hexagons from Uber's H3, etc. No grid is perfect because the earth's geometry is not perfect, but pentagons have some distinct use cases (e.g. if you need equal areas) in which they perform better.
It's all pretty well discussed in this episode of the Geomob podcast with Felix Palmer, A5's creator.
Writing a good CLAUDE.md
"Since Claude doesn't know anything about your codebase at the beginning of each session, you should use CLAUDE.md to onboard Claude into your codebase."
Finally a well-explained but not 100-pages long write-up of how to get a good CLAUDE.md :-) I've used this approach in a few projects (e.g. Better Word Counter) and it does really help in building solid, testable applications.
Note that "this post is also applicable to AGENTS.md, the open-source equivalent of CLAUDE.md for agents and harnesses like OpenCode, Zed, Cursor and Codex."
However, note the issue with too much instructions as per chart below.
Better than JSON
This coder stopped using JSON for something safer and faster (Protobuf). I'm not sure I'd want the extra faff for simple data exchanges, but as your product grows it might be worth looking at this.
Introduction to Asynchronous JavaScript
A good and clear course.
"Now, tasks queued on the main thread can include asynchronous actions, like responses to requests made with fetch, timers specified with setTimeout or setInterval, or handlers for user interaction registered via addEventListener. These are all approaches to asynchronous JavaScript that depend on callback functions (usually just “callbacks”) — functions that are invoked when a condition is met."
🤯 Data thinking
What makes something data?
"There are many different conceptualizations of “data” in many different fields of study, but machine learning and “AI” especially stand out for eschewing the idea that what makes something data crucially involves a connection to some research question and careful, replicable collection."
📈Dataviz, Data Analysis, & Interactive
Credit Union Mortgages: Updated Daily
"...we built a daily-updated comparison of mortgage rates from over 120 credit unions across the United States."
Costco Damage to Wallet - Fork
A personal project to create a dashboard to track the OP's own Costco expenditure, turned into a (broadly) reusable script to harvest the data and a website to visualize it. I presume this is based on US-based Costco, but it might work (maybe with some adaptation) to other countries.
The Globe of History
This is "an ongoing effort to visualize significant events and people from the last 6,000 years of human history on an interactive map.".
It's not just a nice visualization, but it's based on a good methodology (for the AI era): a pipeline that combines programmatic harvesting, and AI enrichments, and manual quality controls.
(via Geomob)
Half year of birb data collecting update
Randy Au: "Winter is here and bird season by my office window has been winding down, and so I went back to the birdnet server I have running and checked up on the data it was collecting."
Where does my trash go?
Linus Aarnio for Datawrapper looks at recycling.
Which states contribute the most and least to federal revenue?
"In 2024, Californians paid about $275.6 billion more to the federal government than they received."
It varies wildly by state, USAFacts report. Some of the charts here are really pretty.
🤖 AI
Part 3: The Proposed Solutions
Part 3 of Nicky Case's brilliant comic series on AI Safety is now out.
Don't Push AI Down Our Throats
"AI is being done wrong.
It's being pushed down our throats. It’s in our search bars, our operating systems, and even our creative tools, whether we asked for it or not. It feels less like an upgrade and more like a force-feeding.
It doesn’t need to be this way. Technology can be adopted slowly. Organically. One piece at a time."
This is true of every technology, which is why I always say to stop treating AI as something magic.
How I Reverse Engineered a Billion-Dollar Legal AI Tool and Found 100k+ Confidential Files
Alex Schapiro, a Yale student and freelance pentester, talks about his practical research into LLM vulnerabilities: "Zero authentication, full admin access, and a privacy nightmare for lawyers."
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