Early access · Amazon.co.jp
Buy, price and ship on profit.
EC THUNDER connects your Amazon sales, competitors, suppliers and books. It shows what to buy, what to charge and what to send in, catches problems while they're small, and does the slow work for you, so your time goes on what earns.
Now onboarding a small number of Amazon Japan sellers.
Thunder-fast
The slow parts, done in seconds
- Secondsto plan a restock
- Every product, open order and Amazon's own restock sheet, scored and ready to order.
- 1 clickfrom plan to PO
- Draft the purchase order straight from the plan, split by how you'll pay.
- 0Seller Central visits
- To build an FBA shipment, from choosing what to send to printing the box labels.
- 1confirmation
- Only where Amazon charges you for freight, with the price on screen first.
Restock planning
Restock for profit, not just volume.
- Why each product is bought, or left out
- Seasons, Subscribe & Save and lead times included
- Your rules: always buy, never buy, prioritise
Amazon's restock recommendation is built to keep you in stock, from your sales history. But Amazon can't see what you actually pay your suppliers, your payment terms or the cash you have. EC THUNDER plans with all of it, so the same budget goes first to the products that leave the most profit. Amazon's recommendation is costed the same way and kept beside it, so you can compare and adjust either one at any time.
How planning worksBuy ¥100 of stock. Once it sells and Amazon's fees and freight to FBA are paid, this is what your ¥100 comes back as.
- Buy ¥100 of stock
- It sells on Amazon
- Paid out after fees and freight
- Your ¥100 comes back as ¥147.5
Measured on our own account, October 2026: same budget, both plans costed the same way.
These numbers are one example. Results vary with timing, budget, products, prices and each item's margin. Check yours with your own data during the trial.
Competitor analysis
See exactly where you stand against every rival.
- Rivals found and compared for you
- Accurate price, sales rank and offer count
- Rival stock-outs and lost Buy Box flagged fast
Price against sales rank on one map. Rivals that are cheaper and selling better land in the red zone. Prices are compared per unit of your pack size, and every rival shows what you'd keep if you matched it.
Competitors and pricingRepricing with guardrails
AI proposes. Rules protect. You decide.
- A loss-making price can't go live
- Gradual raises and sales covered too
- Every proposal, approval and refusal recorded
The AI reads your competitors and suggests one price. Code checks it twice, when it's proposed and again right before it's written, against your floor price, step size, 24-hour limit and the Buy Box. A price that loses money can't reach Amazon.
See the safety checksYour AI companion
Rules do the math. AI explains it.
- Context, automatically
- Open it on a product and it has that product's sales, stock, margins and competitors loaded.
- One click or any question
- Pick a suggested question for the page you're on, or ask anything in your own words.
- The model you trust
- Choose between Claude and GPT models for each question, from fast to most capable.
- Advice, never actions
- Figures come from your data and fixed formulas. The AI can't change Amazon, your prices or your books.
An assistant follows you through every page of the app. It already knows which product or screen you're on and reads the data it needs by itself, then gives you analysis and advice with its sources cited.
✓ Loaded: this product's sales, stock and rivals
Plan → PO → prep → FBA
From restock plan to FBA shipment, without opening Seller Central.
- FNSKU labels just like Amazon's
- Part shipments: just change the number
- One confirmation: the freight
Draft the purchase order from the plan. When the goods arrive, the prep sheet tells the bench what to build and prints FNSKU and recipe labels. Tick what to send and create the shipment: EC THUNDER runs Amazon's free steps and stops only where money is spent.
Prep and shipments- ✓ Box labels print
Books & analytics
Amazon payouts, straight into your books.
- Payouts booked and matched to the bank
- Invoices and bank statements: just upload
- Wholesale and consulting in the same books
Each Amazon payout is split into sales, fees, advertising and refunds, booked automatically, and checked against the money that actually reached your bank. Consumption tax is kept apart from sales. When sales go up or down, you can see whether visitors, the share who buy, or price caused it.
Books and analyticsAmazon payout · Oct 1–14
Consumption tax kept apart from sales
One place
What EC THUNDER replaces
- The restock spreadsheetA plan scored by profit per yen, within your budget
- A dozen product-page tabsOne map of every rival's price and sales rank
- A repricer you have to watchProposals that can't go below your floor
- An afternoon in Seller CentralPrep sheet, labels and shipment in one flow
- Typing payouts into accounting softwareSettlements posted and matched to the bank
Why we built it
Built by a seller, for our own Amazon business first.
I've been selling online since 2016: on Amazon in the US, Canada and Japan, on eBay, and through several Shopify stores. Before and alongside that, I spent more than ten years in advertising technology, building systems that make fast decisions from large amounts of data.
EC THUNDER is the tool I wanted and couldn't find. It runs MJ World's own Amazon Japan business every day, so every feature on this page was built for a real problem and is used before it's offered to anyone else.
Hamza Ashraf · Founder, MJ World Japan LLC
Careful with your data
Read about security- Two-factor sign-in and six roles: each person sees only what they need
- No buyer names, addresses or emails requested
- Uploaded documents kept private
- Nightly encrypted backups, every action logged
Questions
Can it change my prices without me?
No. Price proposals are checked against your floor price and written to Amazon only after a person approves them. A gradual price ramp is approved once as a whole, and each step is checked again before it's written.
Does it reprice automatically around the clock?
Not by design. Open-ended automatic repricing is where sellers lose money to price wars and bad data. EC THUNDER proposes prices from competitor data and your margins, and you approve them in one click.
Can I still follow Amazon's restock recommendations?
Yes. Amazon's recommendation is always available beside our plan, costed the same way, with a side-by-side view. You can adjust either one before drafting the order.
Which AI models does it use?
You can choose between Claude (Anthropic) and GPT (OpenAI) models for each question. The AI reads only the data needed to answer the question.
Which marketplaces are supported?
Amazon.co.jp today. Wholesale, consulting and other revenue can be added as their own channels.
See it on your own Amazon data.
Tell us about your Amazon Japan business and we'll set up an early-access account.