ทองที่คุณซื้อตลอดปี — ลอตไหนไหน ตอนนี้เท่าไหร่? บันทึกครั้งเดียว ดูราคาทุกวัน แจ้งเตือนเมื่อถึงราคาที่ตั้งไว้

Source signals

• SIG-20260426-sea-mainland-personal-money-th-gold-investment-portfolio-tracker: "พอดีซื้อทองแท่งลงทุน อยากได้ app คุณสมบัติดังนี้ครับ - ดูราคาปัจจุบัน - ดูราคาย้อนหลังเป็นปีเพื่อใช้ในการตัดสินใจครับ ... อยากได้แบบที่มีคุณสมบัติเหมือน line ประมาณว่าพอมีการเปลี่ยนแปลงราคาในแต่ละวัน ก็จะมีเตือน"

What we ship

**Core features (MVP)**

• Lot entry: purchase date, weight (baht-units, 1 บาท = 15.244g for 96.5% gold), purchase price (auto-prefill from historical spot price on date), shop (dropdown: Hua Seng Heng / MTS-Gold / Aurora / Yaowarat shops / Custom). Optional lot photo (R2 storage)
• Receipt OCR: photo a paper receipt from a Yaowarat shop → Claude extracts weight + price + shop + date → one-tap lot add
• Daily spot price feed (Gold Traders Association of Thailand, 96.5% gold): updated 4×/day, shown on main screen as "ทองคำแท่ง 96.5% — ขาย 32,450 / รับซื้อ 32,350"
• Portfolio P&L: total market value + cost basis + unrealized gain/loss in THB (per lot and aggregate)
• Target alerts: user sets "alert when sell-price > 33,000" → LINE Notify push
• Daily morning summary: LINE Notify "เช้าวันนี้ ทอง 96.5% ขาย 32,500 (+150 จากเมื่อวาน) — พอร์ต ของคุณ มูลค่า 487,500 บาท"
• Sell simulator: "If you sell lot 1 (3 baht @ 28,500) today at 32,450 → profit 11,850 THB"
• Tax helper: physical gold capital gains in TH not subject to consumer income tax (informational disclaimer)

**Primary user flow**

1. Landing "ทองของคุณ ครบทุกล็อต ทุกวันรู้มูลค่า" — CTA "เริ่มฟรี (3 ล็อตแรกฟรี)"

2. LINE Login → quick onboard

3. Add lot 1: "Bought 16 Jan 2024, 5 baht, 28,500 THB/baht, at Hua Seng Heng" → app shows current mark

4. Add lots 2-3 free → unlock paywall (99 THB/mo for unlimited lots + alerts)

5. Daily morning push → user opens app → sees current P&L

6. Sell trigger → user sold lot off-app → marks "sold" → realized gain logged

**What it looks like**

• **Landing**: hero "ทอง 96.5% — ลอตไหนไหน ตอนนี้เท่าไหร่?" + portfolio view screenshot with big THB numbers (large font for older audience) + LINE Notify example
• **Main app screen**: top banner with current spot price (green/red delta), lot list sorted by purchase date, total portfolio value in big font, P&L delta
• **Output / notification**: LINE Notify "เช้านี้ ทอง 96.5% ขาย 32,500 — พอร์ตคุณ +3,250 บาท วันนี้"

**MVP build plan (7 days)**

• Day 1: backend (User, Lot, PriceSnapshot, Alert), JWT, LINE Login
• Day 2: Gold Traders Association price feed + daily cron + historical-price prefill
• Day 3: Lot CRUD + portfolio P&L engine
• Day 4: receipt OCR (Claude) + R2 photo storage
• Day 5: target alerts + LINE Notify + daily morning summary cron
• Day 6: TH-first landing with big-font UI + Omise subscription
• Day 7: deploy CF Pages + Railway, soft launch via Pantip /investment-club + Facebook gold-investor groups

Reasoning

Physical gold is a deeply cultural TH form of savings (wedding gifts, generational, emergency liquidity). Many households hold lots, and Pantip /investment-club regularly shows "อยากได้ app บันทึกเป็นล็อต" requests — but no one builds it. Existing apps (ThaiGoldAlert, GoldPrice Update, SiamGold) are simple tickers, not portfolio trackers. White-space is obvious. Build is trivial (7 days) — Gold Traders Association price feed is public, P&L formula is straightforward, LINE Notify is free, receipt OCR via Claude is ~50 lines. Recurring revenue is sustainable: gold investors are long-term (generational), good retention. Adjacent revenue — affiliate with large gold shops (Hua Seng Heng, MTS-Gold) for buyback flow ("sell lot 1 via MTS-Gold → +0.5% from spot"). Distribution — TH gold-investor communities are active (Facebook groups, Pantip /investment-club, LINE Open Chat).

Quick competitive read

TH market scan — 0 direct portfolio-level competitors:

• **ThaiGoldAlert**: price ticker, alert on absolute price; no lot-tracking
• **GoldPrice Update**: ticker + historical price; no portfolio
• **SiamGold**: ticker + weight unit converter; no portfolio
• **Aurora app**: shop-specific ticker from Aurora chain; not aggregator
• **Excel in Google Drive**: status quo, manual, no current P&L
• International: **Goldstockportfolio.com** — desktop web, not TH (USD, no THB/baht-weight)
• White-space: **TH-localized portfolio tracker for physical gold with lot-level P&L + LINE Notify + receipt OCR** — none on market. Competitive pressure 8/10.

Initial pricing hypothesis

Freemium: 3 lots free, then 99 THB/mo for unlimited lots + price alerts + daily morning summary. Premium 199 THB/mo — receipt OCR + sell simulator + tax helper + Hua Seng Heng buyback affiliate. Plus affiliate revenue from buyback at large gold shops (typical commission 0.3-0.5% of sell-side amount). 5K paying users × 99 THB × 12 mo = 5.94M THB/year ≈ $170K USD ARR (target year-1).

Distribution hypothesis

Pantip /investment-club soft-launch by replying to "อยากได้ app บันทึกเป็นล็อต" questions. Facebook groups: "ลงทุนทองคำ", "ทองคำแท่งวันนี้", "Gold Investor Thailand". LINE Open Chat for gold traders. TikTok video: "บันทึกลอตทอง 5 ปี — กำไรจริง 240,000 บาท" storytime. Aommoney.com guest post on gold portfolio diversification. Yaowarat shop partnerships — print "บันทึกลอตของคุณฟรี" QR on paper receipts in exchange for affiliate buyback.