Why I built this

Fill the gap between heavy government sites and high-bar paid platforms with free, in-browser micro tools. Inputs never leave your device, and the free tier of every existing tool is permanent. The goal: small tools you can build once and use for life.

Concretely: most "small Korean life decisions" — checking jeonse risk before signing a lease, comparing capital-gains vs. gifting tax, validating a fixed-wage contract, drafting a certified notice, calculating Black Friday customs duty — should not require an accountant, a lawyer, or a paid SaaS subscription. They should take 60 seconds in a browser tab. bal.pe.kr is the portfolio that makes that possible.

Trend-driven SaaS tends to rebrand or reprice itself every 6 to 18 months — basically a self-renunciation cycle. Users pay the migration tax every time: re-learning shortcuts, re-importing data, getting a fresh invoice. The bal.pe.kr tools opt out of that cycle by design — there is no account, no server-stored state, so there is no "migration" event to inflict on you.

Concrete example: the fixed-wage validator (pogalwage) has not changed its input form since it shipped in 2024. When the labor-standards enforcement decree gets amended, the formula updates silently — but the screen the user already memorized stays put. The fact that 119 of these "learn once, use forever" tools have piled up is exactly why I keep building one more every weekend.

Not a temporary ad farm. The single rule that runs through this whole portfolio is: in five years, even ten years, the same URL should still do the same calculation.

jkRaccoon · @jk_raccoon

Day job: software engineer. Side project: this place.

I work as a software engineer by day. bal.pe.kr is what I build in the evenings, on weekends, and during my newborn's nap windows. Unlike work deadlines, the only release criterion here is "will I want to use this again next month?"

It started simple. A friend texted me right before signing a jeonse lease — "this looks like a phantom-deposit case, how do I check?" The next month a junior who had just changed jobs asked, "my new contract is fixed-wage; is this even legal?" The month after that, my parents asked, "capital-gains tax versus gift tax — which is cheaper?" After explaining the same math three or four times, I figured it was less wasteful to ship a permanent free tool that any friend, or any stranger, could reuse forever. That habit eventually grew into 119 tools.

• GitHub @jkRaccoon
• Threads @jk_raccoon
• comsamo84@gmail.com

Why I keep doing this

The default fate of a side project is "hot for a quarter, then dead." The reward of this portfolio is the opposite shape. The fixed-wage tool I shipped last year still gets the same weekly traffic this year. The capital-gains calculator from two years ago gets a steady search volume regardless of where the property market is. The joy is watching "forever-lasting tools accumulate, one by one" — that is the difference from a single-shot SaaS. One a week is fifty in a year, two-hundred-fifty in five years — a quietly compounding library of utilities that just keep working.

How the parenting tools started

Our first child was born on May 27, 2025. Suddenly daily life was full of tiny counters — "how many hours did the baby sleep," "how many diapers did we change," "when was the last feed?" The existing apps for this either demanded a signup, or were ad-saturated, or both. So I built yebang (vaccination calendar), suyu (feeding timer), and diaper (diaper counter) myself — no login, inputs only in localStorage, ads only below the result. Other parents of newborns are dealing with the exact same friction, so I shipped them in Korean and English.

Solo developer jkRaccoon. Focused on Korean real-estate, tax, and labor domains; some code is open at GitHub @jkRaccoon. The shared infra lives in microsaas-infra.

These are not marketing copy — they are operational rules. Every new tool is reviewed against them before it ships, and a tool that cannot meet them (e.g., needs a server-side login) is rejected from this portfolio.

The six principles, with concrete examples

1. 01

   🔓No login or signup — every tool is instantly usable

   Example: pogalwage, yebang, and yangdo all open straight to the input form. There are zero signup, email-verification, or social-login steps. The average first-input latency across the portfolio is under one second.

2. 02

   🛡️No personal data collected — inputs stay in the browser

   Example: yebang stores the child's birthday and vaccination history only in the user's browser localStorage — nothing is sent to any server. Even the operator cannot see which child got which shot.

3. 03

   ✨All tools free — ads cover hosting, free tier is permanent

   Example: all 119 tools are committed to a forever-free tier. Hosting is funded by ads; in months where ad revenue does not cover the AWS bill, my day-job paycheck covers the gap. There will never be a surprise paywall on a tool you already use.

4. 04

   📚Sources cited — every statute, ruling, and public dataset

   Example: the capital-gains tool cites Income Tax Act article 95 and enforcement decree 167-5; the fixed-wage tool cites Supreme Court ruling 2010 Da 91046. Every calculation has its statutory source linked at the bottom of the tool.

5. 05

   🤝Experts first — outputs are advisory, decisions belong to licensed pros

   Example: every tool's result screen ends with the standard footer "This is informational. Please review with a licensed tax accountant or labor attorney before filing or signing." That footer is auto-injected, not optional.

6. 06

   🔄24-hour fix policy — bug and law-change reports welcome

   Example: November 2024 comprehensive-real-estate-tax fair-market-value ratio change, March 2025 four-major-insurance rate change — both reflected in the affected tools within 24 hours of the effective date. The average fix time for user-reported calculation bugs is roughly nine hours.

Live

213

Planned

0

Hubs

12

Of the 213 live tools, 172 are Korea-specific (real estate, labor, retirement, seller hubs) and 41 are language-agnostic developer / media utilities. Monthly visitor count is in the low five-figures and growing roughly 15–25 % month-over-month as new hubs come online.

Hubs are not arbitrary buckets — they are domains I have personally lived in for at least a year before grouping the tools. Every hub answers exactly one question for the visitor.

• 🏠Real Estate & Tax20 live

  Buy, rent, capital gains, gifting, loans — Korea edition

• ⚖️Labor & Contracts10 live

  Work, lease, demand, and notice documents auto-generated

• 💍Wedding & Events7 live

  Invitations, gifts, budget — tools for once-in-a-lifetime events

• 🏦Retirement & Finance6 live

  National pension, reverse mortgage, retirement health insurance

• 🧑‍💻Developer & Digital Tools30 live

  Small utilities usable anywhere in the world

• 🍚Life & Health78 live

  Korean daily life tools: food, health, lifestyle

• 🚗Automotive10 live

  Car tax, fuel economy, and used-car calculators for Korea

• 🐶Pets4 live

  Pet owner calculators: feeding, age conversion, health

• 🛒Shopping & Overseas5 live

  Overseas customs, Black Friday FX, and Smart Store SEO — for shoppers and sellers

• 💼Seller & Commerce25 live

  Fee, settlement, and margin calculators for Korean marketplace sellers

• 🍼Parenting11 live

  Feeding, weaning, diapers, vaccines, and development tools

• 🎮Games7 live

  Tools for gamers: LoL MMR, MapleStory EXP, Steam pricing, season calendar

Frontend

React 19 · React Router 7 · Vite 6 · Tailwind CSS 3 · i18next

Build & SSG

Vite SSR pre-rendering · ISR-style static export · sitemap.xml generator

Hosting

AWS S3 (origin) · CloudFront (CDN, KR + Global PoP) · ACM TLS · Route 53

Infra-as-code

AWS CDK 2 (TypeScript) · shared OAC + CloudFront Function for path rewrites · per-tool stack reuse

Analytics

Google Analytics 4 (anonymized) · Naver Webmaster Analytics · Search Console / Naver Search Advisor

Monetization

Google AdSense (Auto + manual placements after 80% content fill)

CI / Deploy

Local CDK deploy script (microsaas-infra/scripts/local-deploy.sh) — GitHub Actions on standby

None of this was built in a sprint. It is the cumulative answer to moments when a friend, a family member, or I myself muttered "I really do not want to compute this by hand again." A few of the early dates are reconstructed from memory and marked as such.

1. 2024-09approx.

   bal.pe.kr domain registered. First Korean micro-tool — pogalwage (fixed-wage validator) — shipped on its own subdomain as a weekend project.

2. 2024-10 ~ 12approx.

   Five to ten early tools built (yangdo capital-gains, jeonse-risk, naeyong notice generator, etc.) — mostly answering tax / contract / lease questions friends had texted me about.

3. 2025-01

   Shared infra (microsaas-infra: CDK + S3 + CloudFront + ACM + ACM-DNS-validation pattern) extracted. Per-tool repo template standardized so a new tool only needs a fresh subdomain and a stack import.

4. 2025-05-27

   Our first child was born. The motivation for the parenting hub (yebang vaccination calendar, suyu feeding timer, diaper counter) came directly from running these counters by hand at 3am.

5. 2025-06

   bal.pe.kr consolidated as the canonical hub. ~50 live tools across 6 hubs.

6. 2025-10

   Bilingual KR / EN routing rolled out for every tool; XML sitemap and IndexNow wired up.

7. 2026-01

   Crossed 100 live tools and 12 hubs. Seller hub launched targeting Korean marketplace operators (Coupang, Naver Smart Store, 11st, GMarket, Olive Young, Musinsa, Baemin, Cafe24).

8. 2026-04-20

   Started the "Useless Development 100" Threads series — one tool per day introduced publicly. #1 was ytchapter (YouTube chapter generator).

9. 2026-05-04 / 05

   Two of the tools (yebang and firekr) went viral on Threads back-to-back, validating the "permanent free Korean micro-tool" niche.

10. 2026-05-09 (today)

    119 live sites, 24 long-form blog and guide articles, AdSense review in progress, hub portal (this site) shipping the operator section you are reading right now.

• 서울 / 수도권 청약 가점 자동 계산기 (정부 청약홈 데이터 매핑)
• 내년 4대 보험 요율 적용 월급 시뮬레이터
• 프리랜서 종합소득세 1분 추정기 (단순·기준·간편 비교)
• 소상공인 카드수수료 환급 자가 진단
• 전세 사기 위험도 — 등기부등본 PDF 1장 업로드 진단
• 아이폰·안드로이드 영수증 자동 OCR → 가계부 CSV
• 한국 학원비 영수증 발행 자동화
• 결혼식 좌석 배치 드래그 앤 드롭 도구
• 강아지·고양이 사료 비교 — 단백질·g당 칼로리 자동 정렬

Tool requests are tracked alongside search-demand data and law-change calendars. The most upvoted requests get prioritized — see the Roadmap page for live status.

Q.Is this really all free? How is it funded?

A.Funded entirely by AdSense. There is no plan — ever — to charge users. It works because labor cost is zero (one operator, side project) and the AWS S3 + CloudFront bill for static sites is on the order of tens of dollars per month.

Q.How does one person ship 119 tools?

A.There is a shared CDK library (microsaas-infra) that gets reused for every tool. Domain, SSL, CDN, sitemap, and analytics are added with a few lines of code per launch. Average build time per tool is one to two weekend afternoons; most of that time is research, citation checking, and UX polish — not the tool logic itself.

Q.Won't the ads get more aggressive over time?

A.AdSense review is in progress. Even after approval, ads will not be placed on tool input forms or result areas — protecting the calculation flow is an operating rule. Ads only appear below the 80%-content threshold and on blog or guide pages. UX wins over ad density, always.

Q.Can I contribute or suggest something?

A.Please do. The fastest channel is the microsaas-infra GitHub issue tracker. New tool ideas and calculation bug reports also go to the operator email (comsamo84@gmail.com). Pull requests are accepted mostly for the shared infra repo.

Q.What happens if the site shuts down? Will I lose my data?

A.No. Every tool runs entirely browser-side, so there is no server-stored data to lose. The values you enter live in localStorage or in-memory only. Site downtime simply means "no new inputs accepted" — it never means "your existing records vanished." The core logic of several tools is also published on GitHub, so self-hosting remains an option even if the hosted site ever goes away.

Every guide, blog post, and tool description on bal.pe.kr is reviewed against five fixed editorial rules before it ships. The rules exist so a single-operator portfolio can still be held to the same evidence and update bar as a multi-person editorial team.

1. 1. Cite primary sources

   Every legal, tax, fee, or safety claim is anchored to a primary Korean government or financial source — the National Tax Service (hometax.go.kr), MOLIT (rt.molit.go.kr), HUG, MOEL (moel.go.kr), the Korea Customs Service, the National Pension Service, the Health Insurance Service, etc. Secondary sources are used only as supplements, never as the sole authority for a numeric claim.

2. 2. Date every number

   Tax rates, brackets, FX rules, fee schedules, and benefit thresholds are tagged with the year (and where relevant, the month) they apply to. A statement like "the rate is 6%" is rejected; "the 2026 rate is 6%" is the minimum format.

3. 3. No professional-advice claims

   Tools and articles are explicitly self-diagnostic. Where a decision is legally binding (real estate purchase, contract dispute, medical dose), the article ends with a recommendation to consult a licensed Korean professional (공인노무사 / 세무사 / 변호사 / 의사). bal.pe.kr never claims to replace that consult.

4. 4. Update on law changes within 7 days

   When a Korean law, tax rate, or fee schedule changes, the relevant tool and articles are updated within 7 days of the change taking effect. Older content is corrected in-place and the update date is reflected in the `updatedAt` field shown at the top of each article.

5. 5. User-reported errors fixed within 24 hours

   Calculation or factual errors reported via email or GitHub Issues are triaged by the operator within 24 hours. If a fix takes longer, the affected page is temporarily marked with a "검토 중" notice rather than left silently incorrect.

Below are the primary government, financial, and statistical sources cited across the portfolio. Each tool description and each guide article links to the specific source page used for its numbers, but this is the master list for transparency.

• Tax & income

  National Tax Service (hometax.go.kr) · NTS yearly notices · Local-tax-law amendments

• Real estate

  MOLIT real-transaction database (rt.molit.go.kr) · HUG jeonse-deposit insurance · Korea Real Estate Board · iros.go.kr (e-registry)

• Labor & wage

  MOEL (moel.go.kr) · Minimum Wage Council · Korea Workers’ Compensation & Welfare Service (kcomwel.or.kr)

• Pension & insurance

  National Pension Service (nps.or.kr) · National Health Insurance Service (nhis.or.kr) · Korea Employment Information Service

• Customs & overseas

  Korea Customs Service (customs.go.kr) · Bank of Korea exchange rates · OECD

• Marketplace fees

  Coupang seller center · Naver Smart Store · 11st · GMarket · Olive Young · Musinsa · Baemin · Yogiyo (each platform’s published fee schedule)

• Statistics

  KOSIS (kosis.kr) · Statistics Korea · KCDC for vaccination schedules · Korea Pet Health Council

• Developer & format

  Apple HEIF / HEIC reference · libheif source · Crontab.guru cross-check · WHATWG / W3C standards

Each tool and each long-form article has an explicit update cadence. Korean tax brackets, jeonse deposit insurance rules, marketplace fee schedules, vaccination intervals, and minimum wage figures all change at predictable points in the year, so the portfolio operates on an annual review cycle plus an event-driven cycle for ad-hoc legal changes.

• Annual review — every January, all tax / fee / insurance tools are revalidated against the new year’s government notices before being marked "2026-current".
• Event-driven update — when a Korean law or tax rate changes mid-year, related tools / guides are updated within 7 days of effective date.
• User-reported errors — calculation or factual errors flagged through comsamo84@gmail.com or GitHub Issues are triaged within 24 hours.
• Change history — material updates are logged on the operations log page in reverse-chronological order, separately from the marketing-style blog.

This site shows Google AdSense ads. Ads are kept independent of tool accuracy and follow AdSense policies (original content, distinct value). Personalized-ad opt-out is available at https://adssettings.google.com.

Ad placements only appear on pages whose primary content fills at least 80 % of the viewport above the ad slot. AdSense Auto Ads are disabled on tool input forms and result pages so as not to interfere with calculations.

No personally identifiable information (PII) is collected anywhere on bal.pe.kr — no signup, no name, no phone, no email at rest. The only data we look at is anonymous Google Analytics 4 page-view aggregates and Search Console query reports. The full policy is on the Privacy page.

Bug reports, new-tool suggestions, and partnership pitches all go to email → comsamo84@gmail.com

Or visit the dedicated Contact page for all channels (email / GitHub / Threads).