Sorted by the job you're hiring them for, finding products, reading price and demand history, or digging into keywords, because no single tool wins all three.
"Best Amazon seller extension" is the wrong question, these tools do different jobs, and the right answer depends on which job you're doing today. Three distinct jobs:
A serious seller ends up using one tool from the first group and Keepa from the second, the two cover most of the work between them.
| Tool | Main job | Free tier | Paid from | Best for |
|---|---|---|---|---|
| Helium 10 | Research + keywords | Limited | ~$99/mo (annual) | Established brands |
| Jungle Scout | Product research | Trial only | ~$29/mo (annual) | Beginners, smaller sellers |
| Keepa | Price & sales history | Yes (core) | ~$15–19/mo | Everyone, buyers too |
| AMZScout | Product research | Trial | ~$45/mo | Mid-budget sellers |
| CamelCamelCamel | Price tracking | Free | — | Buyers & light sellers |
| SellerApp | Keywords + analytics | Limited | ~$49/mo | Keyword-focused sellers |
We don't publish invented "accuracy: 94%" figures, sales estimates are modelled, every tool's numbers differ, and no one can verify a single percentage from the outside. What we can compare honestly: what each tool's job is, what its free tier genuinely includes, its published entry price, and who it suits. Where a sales estimate is involved, treat it as a directional signal, not gospel, and cross-check big decisions against Keepa's actual history.
Helium 10's Xray extension overlays estimated sales, revenue and competition right on Amazon search results, and it's the front door to the deepest toolkit in the category, keyword research (Cerebro, Magnet), listing optimisation, refund and inventory tools. If you're running a real operation, the breadth pays off. The honest limitation: it's expensive and, after the Starter plan was discontinued in 2026, there's no cheap on-ramp, so the entry cost is now a real barrier for beginners. It can also be overwhelming until you grow into it.
Jungle Scout's extension does the same on-page overlay, estimated sales, revenue, demand, with a cleaner, more guided experience that beginners find easier to act on. Crucially it's around 50–60% cheaper than Helium 10 at every tier, which makes it the sensible starting point for most new sellers. The honest limitation: it's less deep than Helium 10 on keywords and operational tooling, so fast-scaling brands often graduate to Helium 10 later.
AMZScout sits between the two: a capable research overlay with niche and product-database tools, priced below Helium 10. A reasonable middle option. The honest limitation: it lacks the brand weight and ecosystem depth of the top two, so it's rarely the standout pick unless its price lands exactly in your budget.
Keepa is the one tool almost everyone in this list ends up using, because its price-history graph appears right on the product page and is genuinely free. The free tier also covers price-drop alerts and tracking up to 5,000 products. The paid plan adds sales-rank history (a proxy for demand), detailed product data and API access. The honest limitation: the most seller-relevant data, sales-rank history, sits behind the subscription, so free Keepa is fantastic for price context but you'll pay for full demand analysis.
The long-running free price tracker. Its companion extension (The Camelizer) shows price history and lets you set drop alerts at no cost. The honest limitation: it's narrower than Keepa, price-focused, with less seller-grade demand data, so sellers use Keepa while many buyers are perfectly served by Camel.
SellerApp focuses on keyword discovery, listing quality and PPC analytics, useful if optimisation rather than product-finding is your bottleneck. The honest limitation: Helium 10 covers much of the same ground inside a single subscription, so SellerApp makes most sense if its keyword workflow specifically fits you better, otherwise you risk paying twice for overlapping tools.
Be clear-eyed: the serious research suites (Helium 10, Jungle Scout, AMZScout, SellerApp) are paid, and the free "trials" are short. The genuinely free value is concentrated in Keepa (price and basic tracking) and CamelCamelCamel (price tracking). A sensible starter stack for a new seller is free Keepa plus one paid research tool, Jungle Scout for most, not three overlapping subscriptions. Add Helium 10 when your volume justifies its depth and cost.
Reading public product data with a browser extension is standard practice and the major tools are established companies; Amazon acts on abuse (review manipulation, fake orders, automating actions against its terms), not on research overlays. On the extension-safety side, these tools request access to Amazon pages and send data to their servers to compute estimates, which is expected, but the category attracts cheap imitators promising "free Helium 10 data". Install only the official vendor's extension. If you're unsure about any seller tool before installing, run it through our Extension Safety Checker.
Keepa and CamelCamelCamel have the widest reach, with Firefox versions alongside Chrome, and all of these install on the Chromium browsers (Edge, Brave, Opera, Vivaldi) straight from the Chrome Web Store. The full seller suites, Helium 10, Jungle Scout, AMZScout, are built Chrome-first; Firefox support is partial and Safari support is rare. Since serious Amazon research happens in a desktop Chromium browser, that's where these tools are designed to live.