Storefront tracking software monitors specific Amazon sellers and tells you the moment they add a new product or restock an old one. It matters because a seller who keeps rebuying a product has already proven that product sells and makes money, so their catalog is research someone else paid for. As of August 2026 the practical options are Arbitrage Stalker for continuous seller monitoring with capped feeds and sub-90-second alerts, Threecolts Seller 365 if you want bulk retailer scanning bundled with back-office tools, Keepa for the price and rank history underneath every decision, and SellerAmp SAS for fast per-product analysis once a lead is in front of you. Below is how they differ, and where each one loses.
Straight disclosure before you read further: I build Arbitrage Stalker. This is a first-party comparison, so I have written it the way I would want to read one, including the parts where other tools beat mine. Prices are as of August 2026 and every one of these companies changes them, so check before you buy.
Why storefront tracking beats scanning retailers cold
Most sourcing advice tells you to open twenty retailer tabs and start pasting UPCs into a calculator. The problem is the hit rate. When you scan a catalog cold, almost everything you look at fails on margin, on sales velocity, or on a Buy Box you cannot win. You only find that out after spending a few minutes per product. Across a full session, you spend most of your time confirming that products do not work.
Storefront tracking inverts that. Instead of asking "does this product sell," you start from products that demonstrably already sell, because a real competitor is spending real money to keep them in stock. That single change is why reverse sourcing became the default method for sellers who source consistently.
The catch is that doing it by hand does not scale. Checking even thirty storefronts manually is a part-time job, and restocks do not wait for you to refresh. That is the job software is for.
The comparison
| Arbitrage Stalker | Threecolts Seller 365 | Keepa | SellerAmp SAS | |
|---|---|---|---|---|
| Core job | Watches sellers, alerts on adds and restocks | Bulk retailer catalog scanning plus back office | Price and sales rank history | Per-product profitability analysis |
| Continuous seller monitoring | Yes | No | No | No |
| Alert speed on restocks | Under 90 seconds | Not an alerting tool | Price-drop alerts only | Not an alerting tool |
| Feed exclusivity | Capped per plan | Shared scan results | Public data | Public data |
| Entry price | $29/mo | $69/mo | Euro-denominated, check site | $19.95/mo |
| Free trial | 7 days, card required | 14 days | Free tier available | 14 days |
Prices as of August 2026.
Arbitrage Stalker: best for continuous seller monitoring
Arbitrage Stalker watches roughly 1,900 storefronts around the clock and catalogues about 342,000 products. You choose which proven sellers to track. When one of them adds a product or restocks, the find lands in your feed and pings Discord, Slack, or Telegram in under 90 seconds.
The part that matters more than speed is the cap. Every feed is capped by plan and tied to sellers you personally choose, which means your finds are not blasted to a few hundred other subscribers at the same moment. A lead that five hundred people already have is not a lead, it is a race to zero margin that you are entering last. Capping the feed is the entire point.
Three supporting pieces close the loop. Apex, the buy-or-pass call, reads demand, competition, and profit math before you spend a dollar. Source Radar shows you where to actually buy a winner. Profit Pipeline carries the deal from saved lead through buy, sell, and rebuy, so a product that worked once comes back around instead of getting forgotten.
Where it loses: if what you want is to scan an entire retailer catalog against Amazon in bulk, that is a different job and Tactical Arbitrage inside Seller 365 does it better. Stalker is a seller tracker, not a catalog crawler.
Plans run $29, $59, and $239 per month, with a 7-day trial that requires a card. Full breakdown on the pricing page.
Threecolts Seller 365: best for bulk scanning plus back office
Worth knowing if you have been out of the loop: tacticalarbitrage.com/pricing now redirects to Threecolts Seller 365. Tactical Arbitrage is one of ten tools in that bundle, alongside InventoryLab, ScoutIQ, Scoutify, ScoutX, SmartRepricer, and the FeedbackWhiz products.
For a seller who wants bulk retailer-to-Amazon matching and accounting and repricing under one subscription, that consolidation is good value. Reseller pricing is $69 per month for one user, $129 for teams up to ten, and $199 for the Pro tier with premium support, on a 14-day trial.
Where it loses: none of the ten tools continuously watches a chosen set of seller storefronts and alerts you on restocks. Bulk scanning tells you what exists in a retailer catalog. It does not tell you what a proven competitor just rebought.
Keepa: the layer underneath everything
Keepa is the price and sales-rank history for Amazon, and effectively every serious sourcing decision in this industry rests on it. It is not a storefront tracker and does not try to be. It answers "what has this product done over time," which is exactly the question you need answered once a lead reaches you.
Arbitrage Stalker runs on Keepa data, so I am not going to pretend there is a rivalry here. The honest framing is that Keepa is the data and a tracker is the workflow. Keepa prices in euros and changes its tiers, so check keepa.com rather than trusting a number in a blog post.
SellerAmp SAS: best for fast per-product analysis
SellerAmp answers one question quickly: is this specific product worth buying, at this cost, right now. Profit calculator with fees, ROI, eligibility and IP alerts, Buy Box analysis, historical charts, in a Chrome extension plus web and mobile apps.
Pricing is $19.95, $29.95, and $49.95 per month with a 14-day trial. The tiers share the same features and differ on usage.
Where it loses: it is a decision tool, not a discovery tool. It is excellent at telling you whether a lead is good and does nothing to put leads in front of you. Most sellers who run it well pair it with something that generates the leads. If you want the head-to-head, we wrote a full Arbitrage Stalker vs SellerAmp breakdown.
How to pick
Match the tool to the gap you actually have.
- You cannot find enough leads. That is a discovery problem. A storefront tracker fixes it. Bulk scanners help too, at the cost of sharing results.
- You have leads and keep buying losers. That is a validation problem. SellerAmp or Apex fixes it, and no amount of extra leads will.
- You find good deals but never rebuy them. That is a pipeline problem, and it is the most expensive one on this list because you already did the hard part.
- You want fewer subscriptions. Seller 365 consolidates ten tools. That is a real argument.
For the wider tool landscape beyond tracking, see our roundup of the best Amazon arbitrage software, and if you are just starting out, the beginner tool guide is a better entry point than this page.
The honest summary
If you already know how to evaluate a deal and your bottleneck is finding enough of them without buying into a shared list, a storefront tracker is the subscription that pays back fastest. That is the case Arbitrage Stalker is built for, and it is the only one on this list doing continuous seller monitoring with capped feeds.
If your bottleneck is anywhere else, buy the tool that fixes your actual bottleneck. Tool sprawl is how sellers end up paying $300 a month to stay exactly as stuck as they were.
Let the deals come to you
Arbitrage Stalker watches proven storefronts, scores every lead against your numbers, and tracks each deal to sold and rebuy. Capped feeds keep your finds exclusive.
Start your 7-day free trial