Guides & explainers
15 plain-English guides explaining the formulas, rules and ideas behind our tools — so you understand the numbers, not just see them.
🛠️ Developer Tools
All developer tools →How to Fix Invalid JSON
A practical guide to JSON parse errors: how to read the error message, the eight most common causes (trailing commas, single quotes, unquoted keys) and how to fix each.
GuideWhat is Base64 Encoding?
Base64 explained: what it does, why binary data needs it, how the 3-bytes-to-4-characters scheme works, the = padding, URL-safe Base64 — and why it is not encryption.
GuideWhat is a JWT (JSON Web Token)?
JWTs explained: the header.payload.signature structure, what claims are, why signed is not encrypted, how verification works and where JWTs are used.
GuideURL Encoding (Percent-Encoding), Explained
Why URLs need percent-encoding, what %20 means, reserved vs unreserved characters, encodeURI vs encodeURIComponent, and the bugs (double-encoding) to avoid.
💰 Finance Calculators
All finance calculators →What is GST? A Plain-English Guide
GST explained for India: how the Goods and Services Tax works, CGST vs SGST vs IGST, the current slabs, who must register and how input tax credit works.
GuideGST Slab Rates in India, Explained
Current GST slab rates in India after the 2025 rationalisation: what falls under 0%, 5%, 18% and the 40% demerit rate, how CGST/SGST split works, and how to find your rate.
GuideHow to Calculate GST (Add and Remove)
Step-by-step GST calculation: the formula to add GST to a base price, the reverse formula to remove GST from an inclusive price, worked examples and common mistakes.
GuideGST for Freelancers in India: When You Must Register
Do freelancers in India need GST registration? The ₹20 lakh threshold, export of services and LUT, the 18% rate, invoicing basics and returns — explained simply.
GuideHow EMI Is Calculated, Step by Step
The EMI formula explained with a worked home-loan example: how banks compute your monthly instalment, why early EMIs are mostly interest, and what changes your EMI.
GuideHow to Reduce Your Home Loan EMI
Practical ways to cut a home loan EMI or total interest in India: prepayment strategy, rate negotiation and balance transfer, and the EMI-vs-tenure trade-off explained.
GuideFlat Rate vs Reducing Balance: Why the 'Cheap' Loan Isn't
Flat interest rates look about half the price of reducing-balance rates but cost nearly the same — or more. The difference explained with one worked example.
GuideSimple vs Compound Interest: the Difference That Builds Wealth
Simple and compound interest compared with the same numbers: formulas, a 10-year example, the rule of 72, and where each type shows up in real life.
GuideWhat is a SIP and How Does It Work?
SIP (Systematic Investment Plan) explained: how monthly mutual fund investing works, rupee cost averaging, the role of compounding, and what SIPs do and don't guarantee.
GuideSIP vs Lumpsum: Which Should You Choose?
SIP or lumpsum? When each approach wins, what the math says about time in the market, and the practical answer for salaried investors and windfalls.
GuideSIP vs FD: Which Is Better for Your Money?
SIP vs fixed deposit compared on returns, risk, liquidity and tax — and a simple rule for deciding which fits each financial goal.