# Notes

> Eighteen short reference pages, each answering one specific question: what a platform, card processor or payout provider actually keeps from a sale, what a platform or a web form counts as one character, which date a military transition deadline is measured from. Every page names the primary source it was checked against together with the date of that check, and says plainly when a figure could not be verified. No account, no upload, no LLM call on any page here — every page is static HTML written once and updated only when a fact it cites changes. This site does not sell anything.

## Pages

- [LinkedIn post character limit: where "see more" actually cuts it off](https://notes.hdg-os.workers.dev/linkedin-post-character-limit): LinkedIn publishes no official character limit, so this documents the observed truncation points and sends readers to Character Limit Checker for the platforms that do publish one.
- [Discord embed character limits explained](https://notes.hdg-os.workers.dev/discord-embed-character-limit-explained): the field, description and 6,000-character embed total limits, with the auto-splitter on Character Limit Checker as the fix once you're over.
- [Twitter/X character limit in 2026: history and why your emoji count differently](https://notes.hdg-os.workers.dev/twitter-x-character-limit-2026): 140 to 280 and the weighted-character rule, then the live counter on Character Limit Checker.
- [Convert a 4.5-scale Korean GPA to the US 4.0 scale](https://notes.hdg-os.workers.dev/convert-4-5-gpa-to-4-0): why three accepted conversion methods disagree, then the calculator that runs all three at once.
- [How many days of terminal leave can you actually take before ETS?](https://notes.hdg-os.workers.dev/army-terminal-leave-how-many-days): the terminal-leave / ETS date / last-duty-day distinction in plain language, then the date calculator.
- [ETS date vs. separation date: which one the paperwork actually uses](https://notes.hdg-os.workers.dev/ets-date-vs-separation-date): ETS, EAOS and EAS name the end of a term, DD Form 214 block 13b records a separation date, and every 365-day and 180-day transition deadline is measured from the latter rather than from your last duty day.
- [What a terminal leave calculator needs before it can give you a number](https://notes.hdg-os.workers.dev/terminal-leave-calculator-what-it-needs): the 2.5 day monthly accrual, the 60 day fiscal-year carryover ceiling, the separate 60 day career sell-back ceiling, and the transition administrative absence that explicitly excludes ordinary end-of-term separations.
- [Your DD214: when you get it, and how long a copy takes later](https://notes.hdg-os.workers.dev/dd214-how-long-after-separation): the form is delivered before departure by regulation and the data reaches DMDC within a day, while a replacement copy years later is a National Archives queue whose own guidance is not to follow up for 90 days.
- [Secret Santa generator vs. a random wheel: which one is actually fair?](https://notes.hdg-os.workers.dev/secret-santa-generator-vs-random-wheel): why a spinning wheel or a naive shuffle can self-match or land unevenly, and what a ghost-leg ladder guarantees instead.
- [Ko-fi vs. Patreon: what each platform actually keeps](https://notes.hdg-os.workers.dev/ko-fi-vs-patreon-fees): a tiered percentage vs. a flat rate with a flat-fee opt-out, then the calculator with your own numbers.
- [What Lemon Squeezy actually charges](https://notes.hdg-os.workers.dev/lemon-squeezy-fees-explained): the 5% + card fee base rate plus the two add-ons a flat-rate estimate misses, then the dedicated calculator.
- [Gumroad vs. Payhip fees: one rate includes the card fee, one doesn't](https://notes.hdg-os.workers.dev/gumroad-vs-payhip-fees): 10% + $0.50 all-in against a 5/2/0 percent plan ladder with Stripe or PayPal billed separately, the algebra showing the cheaper route at every price, and the three monthly-plan breakevens.
- [Stripe vs. PayPal fees: why the gap depends on your price tag](https://notes.hdg-os.workers.dev/stripe-vs-paypal-fees): 2.9% + 30 cents against 3.49% + $0.49 worked at $5, $25 and $200, showing the fixed fee rather than the percentage dominates on cheap products.
- [Payoneer vs. PayPal: what it costs to actually receive the money](https://notes.hdg-os.workers.dev/payoneer-vs-paypal-fees): one provider charges on arrival and the other on conversion, followed end to end on a single $2,000 cross-border invoice.
- [How to block GPTBot and ClaudeBot with robots.txt (and confirm it worked)](https://notes.hdg-os.workers.dev/how-to-block-gptbot-robots-txt): copy-paste rule, then AI Crawler Checker to verify the block actually took effect.
- [애플 구독 환불, 며칠 안에 되나 — 이용약관이 실제로 정한 조건](https://notes.hdg-os.workers.dev/apple-subscription-refund-korea): the 7-day refund window, the e-commerce-law cancellation right and its digital-content limit, quoted from Apple's Media Services Terms, then the full clause lookup. (Korean.)
- [자소서 글자수, 공백 포함인가 — 입력창이 실제로 세는 단위](https://notes.hdg-os.workers.dev/korean-cover-letter-character-count): why "characters including spaces" is the safe default when a job posting does not say, and why a web form counts UTF-16 code units and CRLF-normalized line breaks rather than what a person would count, then Character Limit Checker for the three numbers side by side. (Korean.)
- [해외 후원·판매 플랫폼 수수료, 한국 거주자 기준으로 다시 계산하기](https://notes.hdg-os.workers.dev/korea-creator-payout-fees): South Korea is not on Stripe's supported-country list, which forces the payout route before any headline rate matters, and non-US residence adds surcharges on top; then Creator Payout Calculator for the five-platform net comparison. (Korean.)

## Free tools by the same developer

- [Character Limit Checker](https://char-limit-checker.hdg-os.workers.dev/)
- [GPA 4.5 Converter](https://gpa-convert.hdg-os.workers.dev/)
- [Army ETS Date Calculator](https://ets-calculator.hdg-os.workers.dev/)
- [Ghost Leg Picker](https://ghost-leg-picker.hdg-os.workers.dev/)
- [Creator Payout Calculator](https://creator-payout-calc.hdg-os.workers.dev/)
- [AI Crawler Checker](https://ai-crawler-checker.hdg-os.workers.dev/)
- [Days Until](https://days-until.hdg-os.workers.dev/)
- [한국 서비스 약관 쉬운 말 요약](https://terms-summary.hdg-os.workers.dev/)

## Optional

- [robots.txt](https://notes.hdg-os.workers.dev/robots.txt)
- [sitemap.xml](https://notes.hdg-os.workers.dev/sitemap.xml)