Chrome extension + web app
Smart shopping is about the effective price.
Track Amazon, Rakuten, and Yahoo! prices, and compute the true effective price after Rakuten SPU and shopping marathon bonuses — in one click. The Rakuten reality Keepa cannot show.
No card · Setup in 30 seconds · Browser data only — no PII
- products tracked
- 0
- active alerts
- 0
- drop notifications delivered
- 0
Four differentiators Keepa and Kakaku cannot match
Only on PriceWatch JP
List price − Points back = Effective price
The math Keepa and Kakaku do not show. Enter your multipliers and we factor in Rakuten SPU, shopping marathon, and shop bonuses to compute the real-yen effective price in real time.
- 16.5x SPU stack, shopping marathon, and shop bonuses
- Per-programme monthly caps and the global cap honoured
- Stable yen accounting at 1 point = 1 yen
The total price you would pay
Example: a 5× shop = enter 4
Shopping marathon and similar (max 9)
0 = no cap. Shopping marathon caps at 7,000.
List price10,000 yen
Points earned100 yen
Effective price9,900 yen
1% off
| Feature | PriceWatch JP | Keepa | Kakaku.com |
|---|---|---|---|
| Amazon price history | ✓ | ✓ | ✗ |
| Rakuten Ichiba price history | ✓ | ✗ | Limited |
| Yahoo! Shopping price history | ✓ | ✗ | Limited |
| Rakuten SPU effective price | ✓ | ✗ | ✗ |
| Chrome extension | ✓ | ✓ | ✗ |
| Drop alerts (Web Push) | ✓ | ✓ | ✗ |
| AI buy-timing verdict | ✓ | ✗ | ✗ |
| Japanese-language support | ✓ | ✗ | ✓ |
Two simple plans
Free with 30-day history and 3 alerts. Premium at ¥380/month.
Free
For casual shoppers
¥0
- 30-day price history
- Up to 3 alerts
- Current Amazon / Rakuten / Yahoo prices
Premium
Premium
For serious savers
¥380/mo
- Full-history charts
- Unlimited alerts
- Cross-site comparison
- AI buy-timing verdict
- Automatic Rakuten SPU effective price