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Practical guides covering developer tools, health metrics, SEO, converters and more — written to be actually useful.
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The 300-Year Unbreakable Cipher That Got Broken — Vigenère, Enigma, and What Every "Unbreakable" Cipher Has in Common
FD Calculator — Optimise Your Fixed Deposit for Maximum Return
Learn how compounding frequency affects FD returns, why non-round tenures often offer better rates, how to build a deposit ladder, and how to use a free FD calculator to optimise your fixed deposit strategy.
Fertility Awareness Methods: How the Symptothermal Method Differs from the Calendar Method
The calendar method fails 14–47% of the time. The symptothermal method, properly taught, achieves 0.4–2% failure with perfect use — comparable to hormonal methods. Here's how modern fertility awareness works, how Natural Cycles got FDA clearance, and the contraceptive effectiveness hierarchy.
Your Menstrual Cycle Is a Vital Sign — Here's What Irregular Periods Signal
The menstrual cycle is a vital sign — not just a calendar event. Here's what cycle length, irregularity, and symptoms reveal about stress, thyroid health, PCOS, and nutrition status, and how to track more than just the next period date.
Date Calculator — Calculate Exact Deadlines, Notice Periods & Milestones
Learn why date arithmetic is harder than it looks, the three core date calculation operations, and how to handle legal notice periods, contract milestones, visa limits, and medical schedules with a free date calculator.
How Due Dates Are Calculated — And Why Most Babies Don't Arrive on Them
Only 4–5% of babies are born on their due date. Here's how the 40-week calculation works, why it's imprecise, what "term" actually means, and the real distribution of when babies arrive.
Body Fat Percentage Ranges: What the Numbers Mean and Why Fat Location Matters
Body fat percentage reveals what weight alone can't — but the ranges need context. Here's what different percentages actually mean, why visceral fat carries more risk than subcutaneous fat, and which measurement methods are accurate.
Muscle, Metabolism, and Sarcopenia: Why Building Muscle Is the Best Long-Term Metabolic Investment
Muscle tissue burns roughly 3× more calories per kg at rest than fat. Sarcopenia causes 1–3% muscle loss per year from age 35 onward, gradually lowering BMR. Here's the case for resistance training as a long-term metabolic investment and the protein requirements to support it.
How Much Protein Do You Actually Need? The Evidence-Based Answer
Protein is the macro where most people fall short of the evidence-backed optimal amount. Here's how much you actually need, why leucine triggers muscle protein synthesis, and which foods deliver protein most efficiently per calorie.
JWT Security Vulnerabilities: alg:none, Algorithm Confusion, and Secure Token Storage
The alg:none attack, RS256/HS256 algorithm confusion, weak HS256 secrets, localStorage vs httpOnly cookies, and revocation without statefulness — JWT security vulnerabilities are specific and avoidable. Here's how each one works and how to fix it.
Secure Randomness: Why Math.random() Fails for Security Tokens — and the Right Alternatives
Math.random() in JavaScript is predictable from 128 observations. Python's random module explicitly warns it's not for security. Here's why PRNGs fail for tokens, the secure alternatives in every major language, and the specific bit lengths needed for different security contexts.
API Authentication Methods Compared: Keys, Bearer Tokens, OAuth 2.0, and HMAC
API keys, Bearer tokens, Basic Auth, OAuth 2.0, and HMAC signatures each fit different authentication scenarios. Here's how each method works, when it's the right choice, and how to test each one in an API checker — with the specific header formats.
SSL Certificate Types: DV vs OV vs EV, Certificate Chains, and Preventing Expiry Outages
DV, OV, and EV certificates verify different things. Let's Encrypt is as secure as paid certs for encryption. The chain matters as much as the certificate itself. Here's what SSL certificates actually prove and how to prevent expiry outages.
