Exploring Tech, Finance & Productivity
Practical articles, free developer tools, and finance calculators. No jargon, no fluff.
Design Price Alert System (Stock / Amazon) - System Design
“Notify me when AAPL hits $250” or “tell me when this Amazon item drops below Rs 1,999” sounds like a WHERE price >= target query. Then you …
Read MoreESOP Tax for Salaried Employees: Exercise Year vs Sale Year Changes Everything
Most people think ESOPs are taxed when they cash out. They are not. They are taxed twice, on two different dates, at two completely …
Read MoreThe Management Track Is Not a Promotion - Why Engineers Choose Wrong
The single most expensive career mistake I see senior engineers make is treating the management track as a promotion. It is not a promotion. …
Read MoreDesign A/B Testing System (Optimizely) - System Design
An A/B testing platform is deceptively easy to describe and brutal to get right. “Show half the users the blue button and half the green …
Read MoreDesign ETA Service & Live Location Sharing (Uber) - System Design
Once a rider is matched to a driver, the interesting problem is not “who is my driver” - it is the little car crawling across the map toward …
Read MoreDesign Netflix Screen Limit - System Design
Everyone thinks the screen limit is a counter. “Each plan allows N streams, keep an integer per account, increment when a play starts, …
Read MoreNSC vs Tax-Saver FD vs ELSS: The Real Post-Tax Winner Under 80C
Here is a fact that trips up almost everyone parking money in a tax-saver FD: your fixed deposit and an NSC certificate bought on the same …
Read MoreThe LTCG Exemption Most Indian Equity Investors Leave on the Table
Almost every article on this topic stops at the arithmetic: book Rs 1.25 lakh of gain a year, save 12.5% tax on it, do it fifteen times …
Read MoreDesign Sort 1TB Dataset on Commodity Hardware - System Design
The whole problem is one sentence: the data does not fit in memory. You have 1TB to sort and 16GB of RAM per machine, so the data is roughly …
Read MoreDesign Surge Pricing System (Uber) - System Design
Surge pricing looks like a multiplication. Base fare times some number, show it to the rider, done. The interviewer lets that sit for about …
Read MoreDesign Top K Elements at Scale (App Store Rankings) - System Design
Everyone thinks App Store rankings are a SELECT app_id, COUNT(*) FROM downloads GROUP BY app_id ORDER BY count DESC LIMIT 100. Count the …
Read MoreLTCG Harvesting Every April: The Tax You Are Leaving on the Table
The most common piece of tax advice for equity investors in India is “just buy and hold, don’t churn, LTCG is only 12.5% anyway.” It is not …
Read MoreRate Limiting Is Not Just a Redis INCR Call
Ask most engineers to build a rate limiter and you get the same answer: INCR a Redis key, set a 60 second TTL, reject when the count crosses …
Read MoreCorporate Bond Funds vs FD vs Debt Funds: Post-Tax in 2026
Since April 2023, the standard advice has flattened into a shrug: “debt funds and FDs are taxed the same now, so just pick whatever.” That …
Read MoreDesign Distributed Queue (RabbitMQ-like) - System Design
There are two completely different things people call “a message queue,” and confusing them is the fastest way to fail this interview. One …
Read MoreDesign Google Analytics Pipeline - System Design
Everyone thinks Google Analytics is a counter with a chart on top. “Drop a snippet on every page, count the pageviews, draw a line graph, …
Read MoreDesign Google Calendar - System Design
“Design Google Calendar” sounds like a CRUD app: a user creates an event, it shows up in a grid, the phone syncs it. The interviewer lets …
Read MoreZero-Downtime Deployments Are Hard - Especially When the Database Changes
Most “zero-downtime deployment” tutorials show you two identical stacks, a load balancer, and a switch you flip from blue to green. Traffic …
Read MoreDesign Distributed Stream Processing System (Kafka-like) - System Design
“Stream processing” sounds like a for loop over a queue: read a message, do a thing, write a result. That mental model dies the moment the …
Read MoreDesign Top K Most Shared Articles in Time Windows - System Design
Everyone thinks top-K is a SELECT article_id, COUNT(*) FROM shares GROUP BY article_id ORDER BY count DESC LIMIT 100. Store every share, …
Read MoreDeveloper Tools
JSON Formatter
Format, validate & minify JSON instantly in your browser.
Open ToolJWT Decoder
Inspect JWT header, payload, and expiry without sharing tokens.
Open ToolProtobuf Encoder
Encode JSON to Protobuf binary or decode binary back to JSON.
Open ToolRegex Tester
Test regex patterns with real-time matching and group highlights.
Open ToolBase64 Encoder
Encode and decode Base64 strings with a single click.
Open ToolHash Generator
Generate MD5, SHA-1, SHA-256, and SHA-512 hashes instantly.
Open ToolUUID Generator
Generate random v4 UUIDs. Copy with one click.
Open ToolUnix Timestamp
Convert between Unix timestamps and human-readable dates.
Open ToolFinance Calculators
SIP Calculator
Calculate monthly SIP growth with the power of compound interest.
EMI Calculator
Find your EMI for home loans, car loans, or personal loans.
1 Crore SIP
Figure out how much SIP you need to build 1 crore.
Emergency Fund
Calculate exactly how much emergency fund you should have.
HRA Calculator
Compute your tax exemption under Section 10(13A).
Investment Growth
Project your portfolio's future value with annual step-ups.
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