"I built JustOnlyOneThing because I am a software engineer who actively manages personal investments and uses developer utilities on a daily basis."
Most financial websites on the web today act as commercial lead generators: they capture salary, debt, and mortgage figures to sell to banks and insurance aggregators. Meanwhile, developer utilities frequently send raw authentication tokens, JSON payloads, and encryption keys to untrusted third-party servers.
JustOnlyOneThing was designed with a strict engineering principle: 100% Client-Side Execution. Every calculation runs locally in the browser memory using modern ECMAScript and native Web APIs (SubtleCrypto, FileReader, Canvas). Zero tracking cookies, zero backend servers, zero ads.
A technical exploration into why compounding interest is exponential algorithmic scaling, why sub-millisecond feedback loops eliminate decision friction, and why client-side security is essential for personal financial data.
Read Full Article →30-year unrecoverable cost evaluation comparing mortgages against renting with equity compounding.
Mutual fund compounding schedules with annual contribution increment models.
Format, lint, tree-inspect, query, and compare JSON documents side-by-side in browser memory.
Decode Base64URL claims, expiration countdowns, and client-side Web Crypto signature verification.