Guides from the people who built the tools
Practical writing on images, code, PDFs, colour and money — each piece tied to a tool on this site that does the work for you.
Unix Time: Seconds, Milliseconds, and the Bugs in Between
Unix time counts seconds since 1970. JavaScript counts milliseconds. Almost every mysterious date bug is one of those two being mistaken for the other.
Reading a JWT: What the Three Segments Mean, and What a Decoder Cannot Tell You
A JWT decoder shows you the claims. It cannot tell you the token is genuine — that needs the signing key, which a decoder does not have and should not want.
CodingUUIDs and Hashes: Two Things That Look Random and Are Not Interchangeable
A UUID is an identifier. A hash is a fingerprint. Both are hex strings of fixed length, and using one where the other belongs causes distinct, predictable problems.
CodingBase64 Is Not Encryption, and Three Other Things Worth Knowing
Base64 makes binary data survive a text channel. It is not encryption, not compression, and not a checksum — and anyone can reverse it in one line.
FinanceSIP and FD: What Compounding Actually Does to Your Money
A 12% SIP does not give you 12% on everything you invested. Your first instalment compounds for the full term; your last one compounds for a month.
FinanceGST, Inclusive and Exclusive: The Calculation Everyone Gets Backwards
Removing 18% GST from ₹1,180 does not mean subtracting ₹212.40. The reverse calculation is division, not subtraction, and the difference shows up on every invoice.
PrivacyHow to Merge PDFs Without Uploading Them Anywhere
The documents people most need to merge are the ones they should least want to hand to a stranger's server. There is a better way.
How-ToHow to Compress Images for the Web Without Wrecking Quality
Images are the single biggest cause of slow web pages. Here is what actually moves the needle — in the order that matters.
CodingJSON: The Four Mistakes That Cause Almost Every Parse Error
JSON looks like JavaScript and is not. Four specific differences cause almost every parse error you will ever hit.
CodingRegex for People Who Keep Googling Regex
You do not need to memorise regex. You need about nine building blocks and an understanding of why your pattern matches too much.
DesignColour Contrast: The Accessibility Rule Most Sites Fail
Low-contrast text affects far more people than is usually assumed — and it is one of the easiest accessibility failures to prevent.
SecurityPassword Advice That Is Actually Current
The advice most people follow was formally withdrawn by the organisation that invented it. Here is what replaced it.
FinanceUnderstanding Your Home Loan EMI (and Why Tenure Costs More Than Rate)
Lenders know borrowers compare monthly payments. That is precisely why the monthly payment is the wrong number to compare.
DesignCSS Gradients: Why Yours Looks Muddy, and How to Fix It
Blue to yellow should look vivid. It comes out grey in the middle. Here is why, and what to do about it.