Every calculation runs in your browser — nothing is uploaded Editorial policy About Contact
SkyZap Journal

Guides to the decisions behind the numbers

Long-form, practitioner-written explanations of the money, business and technical decisions our tools help you model. No filler, no affiliate padding.

Developer

JSON-LD vs Microdata: Which Structured Data Format to Use

Schema.org vocabulary can be expressed in three syntaxes: JSON-LD, Microdata and RDFa. They can describe identical information, and search...

February 8, 20263 min read
Finance

The True Cost of Homeownership Nobody Budgets For

First-time buyers budget for the mortgage payment and are then surprised, usually within eighteen months, by how much more the house...

February 5, 20263 min read
Energy

How to Read a Solar Quote: Seven Numbers That Decide Your Payback

Solar proposals are long, glossy and structured to make direct comparison difficult. Two quotes for the same roof will present entirely...

February 3, 20263 min read
Finance

The Price-to-Rent Ratio: A 30-Second Test Before You Buy

Before running any detailed model, there is a single calculation that tells you which way a market leans. It takes half a minute and it is...

January 29, 20263 min read
Business

Factor Rate vs APR: Why a 1.3 Factor Is Not 30% Interest

Factor rates exist because they make expensive money sound cheap. A quote of "1.3" reads as thirty percent. Converted properly, a 1.3...

January 27, 20264 min read
Developer

How to Cut LLM API Costs by 70% Without Changing Models

Most teams' first response to a large AI bill is to switch to a cheaper model, which trades quality for cost. There is usually a great...

January 25, 20263 min read
Finance

Debt Snowball vs Avalanche: What Three Real Payoff Plans Show

The debate is older than personal finance blogging and it usually gets argued in the abstract. Avalanche people say the maths is settled....

January 22, 20263 min read
Business

How to Set Your Freelance Rate: The Backwards Method

The usual method is to look at what other freelancers charge and pick a number in the middle. That tells you what the market tolerates. It...

January 20, 20263 min read
Business

Net Revenue Retention: Why It Predicts Valuation Better Than Growth

If you have one metric on the first slide of a SaaS deck, it should be net revenue retention. It compresses churn, contraction and...

January 16, 20263 min read
Finance

How Much Life Insurance Do You Need? The DIME Method Explained

The most common answer to "how much life insurance do I need" is a multiple of salary — usually ten. It has the virtue of being memorable...

January 14, 20263 min read
Legal

Do You Legally Need a Privacy Policy? A Practical Checklist

The threshold for needing a privacy policy is far lower than most site owners assume. It is not about running a shop or holding accounts....

January 11, 20264 min read
Business

Invoice Payment Terms That Get You Paid Twice as Fast

Late payment is rarely malice. It is almost always friction — an invoice that arrived at the wrong address, missed an approval window,...

January 8, 20263 min read