With over $638 million in daily product sales flowing through Amazon, the platform attracts thousands of new sellers each month. The challenge isn't finding products to sell—it's identifying which products will actually generate profit after fees, storage costs, and competition are factored in. Most Amazon sellers waste hours manually calculating margins, checking restrictions, and monitoring competitor inventory levels across dozens of browser tabs.

Seller Assistant App consolidates this workflow into a single Chrome extension that displays critical decision-making data directly on Amazon product pages. Unlike standalone research tools that require constant tab-switching, this extension overlays FBA calculators, IP alerts, stock levels, and historical pricing data exactly where sellers need it during product evaluation.

This review examines how Seller Assistant App functions in real-world sourcing scenarios, what distinguishes it from competing extensions, and whether its feature set justifies the monthly subscription cost for online arbitrage and wholesale sourcing operations.

What is Seller Assistant App

Seller Assistant App is a Chrome extension designed specifically for Amazon sellers engaged in online arbitrage, retail arbitrage, and wholesale sourcing. The tool functions as an overlay on Amazon's existing interface, appearing automatically on product pages, search results, Seller Central inventory screens, and repricer dashboards.

The extension integrates six core modules: an FBA/FBM profit calculator with real-time fee estimates, an IP alert system based on historical infringement claims, a competitor stock checker, Keepa chart integration for historical data analysis, a restrictions checker tied to your seller account, and one-click export functionality to Google Sheets.

Rather than requiring sellers to navigate to separate platforms or click through multiple screens, Seller Assistant App embeds this data directly into the native Amazon interface. A product that appears profitable at first glance might show negative margins once the extension calculates actual FBA fees, storage costs, and displays an IP alert indicating past brand complaints. This immediate visibility prevents wasted sourcing time and reduces the risk of purchasing restricted or problematic inventory.

The extension supports all major Amazon marketplaces, including US, UK, Canada, Germany, France, Italy, Spain, Japan, and Australia. It functions with or without an active Amazon Seller Account, though certain features—specifically the profit estimator and brand gate checker—require account integration to access seller-specific data.

Seller Assistant App Features

On-Page FBA and FBM Calculator

The profit calculator appears directly on Amazon product pages without requiring additional clicks or pop-up windows. Sellers enter their cost of goods, and the calculator instantly displays ROI, profit margin, net profit, and break-even price. The calculation includes Amazon referral fees (which vary by category), FBA fulfillment fees based on product dimensions and weight, monthly storage costs, and optional fields for sales tax, VAT, and third-party logistics expenses.

For products with variable dimensions or weight, the calculator updates fees in real-time as sellers adjust input values. This is particularly relevant for oversized items where small measurement differences can trigger significant fee increases. The calculator also differentiates between standard-size and oversize tier fees, and flags products eligible for Small and Light program pricing.

The FBM calculator variant removes fulfillment and storage fees while allowing sellers to input their own shipping and handling costs. This comparison helps determine whether a product makes more financial sense for FBA or merchant fulfillment models.

Sales and Profit Estimator

Beyond basic profit calculation, Seller Assistant App estimates monthly sales velocity and projected profit based on the product's Best Sellers Rank (BSR), number of competing sellers, and their respective price points. The algorithm analyzes whether competitors are FBA or FBM, their seller ratings, and current inventory levels to project what percentage of total sales a new seller might capture.

This feature addresses a common sourcing mistake: identifying products with strong margins but insufficient sales volume to justify inventory investment. A product with 40% ROI means nothing if it sells only twice per month. The estimator provides specific monthly sales projections (for example, "estimated 18 units/month at $24.99") rather than vague velocity categories.

The system also calculates required sell-through rates to achieve target ROI thresholds, helping sellers determine optimal order quantities and evaluate whether seasonal trends or declining BSR might impact profitability before inventory sells through.

Break-Even Point and Target ROI Pricing

The extension automatically calculates three critical price points: the break-even price (where total costs equal revenue), a 10% ROI price, and a 20% ROI price. These calculations account for all fees, not just obvious costs like referral fees.

For sellers using automated repricers, these pre-calculated minimum prices can be exported directly to repricer software to establish floor prices that protect margins. Without this safeguard, aggressive repricing algorithms can drive prices below profitability in competitive buy box battles.

The break-even calculator also reveals hidden cost scenarios. For example, long-term storage fees kick in after 365 days for slow-moving inventory. Seller Assistant App factors these extended storage costs into break-even calculations for products with lower sales velocity, preventing situations where slow sellers accumulate storage fees that eliminate initial profit margins.

Keepa Graph and Historical Data Integration

Seller Assistant App embeds Keepa charts directly into its interface, displaying historical price trends, BSR fluctuations, and buy box history without requiring a separate Keepa subscription or browser tab. The integration highlights BSR drops, which indicate actual sales events rather than mere price changes.

The historical view reveals critical patterns: products with steadily declining BSR indicate decreasing demand; sharp BSR spikes followed by drops suggest one-time promotional events rather than sustainable sales velocity; volatile pricing with frequent buy box changes indicates intense competition that may compress margins.

This historical context prevents common arbitrage mistakes like sourcing products during temporary clearance sales without recognizing that the regular retail price normally sits below Amazon's current selling price. The Keepa integration also displays variation history for products with multiple size or color options, helping sellers identify which variations actually drive sales volume.

Export to Google Sheets

A single-click export function sends analyzed product data directly to Google Sheets, capturing over 50 data points including ASIN, current price, all calculated fees, estimated sales, profit projections, competitor counts, restriction status, IP alert history, and custom notes.

This eliminates the manual copy-paste workflow that consumes hours during sourcing sessions. Sellers can analyze 100+ products during a sourcing run, export all viable candidates to a sheet, then review and compare opportunities in a structured format rather than juggling browser bookmarks or scattered notes.

The export includes timestamps and source URLs, creating an audit trail for sourcing decisions. For sourcing teams or VAs, the shared Google Sheet becomes a centralized pipeline where team members can add products, tag them with status indicators, and track which items have been purchased or require further evaluation.

Competitor Stock Checker

The stock checker displays current inventory levels for competing sellers on the same listing. Rather than showing a vague "in stock" indicator, the tool provides specific unit counts (for example, "FBA Seller A: 47 units, FBA Seller B: 12 units").

This intelligence informs inventory purchase decisions. If three FBA competitors each hold 200+ units of inventory, a new seller entering with 50 units faces a longer sell-through period as existing inventory clears. Conversely, listings where the current buy box holder shows only 8 remaining units present immediate sales opportunities for sellers who can source and ship quickly.

The stock checker also tracks inventory changes over time when sellers revisit the same ASIN. Declining competitor inventory suggests strong sales velocity, while stagnant inventory levels for weeks indicate weak demand or pricing issues that may affect a new seller's ability to move units.

Advanced IP Alert System

Seller Assistant App maintains a database of products and brands associated with past intellectual property complaints, trademark claims, and account health issues reported by other sellers. When viewing a product, the extension displays a red warning triangle if the database contains records of IP complaints related to that specific ASIN or brand.

The alert includes specific details: the type of complaint (trademark, copyright, patent, used sold as new), the date it was reported, and whether multiple sellers have encountered issues. This system doesn't guarantee a product is unsafe to sell—legitimate authorized purchases generally face no issues—but it flags increased risk that requires additional verification.

For online arbitrage sellers sourcing from retail websites, IP alerts identify brands that aggressively protect their Amazon channel. Some brands file complaints against any seller not explicitly authorized, even when products were purchased through legitimate retail channels. The alert system helps sellers avoid these high-risk brands or seek explicit authorization before investing in inventory.

The database updates daily as new account health issues are reported across the seller community, providing more current protection than static "gated brand" lists that may not reflect recent enforcement changes.

Brand Gate and Restrictions Checker

The extension checks product selling restrictions against your specific Amazon seller account in real-time. A green open lock icon indicates unrestricted selling permission, while a red closed lock shows the product requires approval or is currently ungated for your account.

This account-specific checking is critical because restrictions vary by seller. One account might have open approval for Nike products while another faces gates. Generic restriction lists don't account for these individual differences, causing sellers to either skip viable opportunities or waste time attempting to purchase inventory they cannot actually list.

The checker also identifies category restrictions beyond brand gates, including hazmat requirements, meltable product flags, adult product designations, and Small and Light program eligibility. These classifications directly impact FBA fees, storage requirements, and shipping restrictions, affecting profit calculations and operational logistics.

Sellers can attach custom notes directly to any Amazon product page. These notes persist across sessions and appear automatically whenever that ASIN loads, whether on product pages, search results, or Seller Central inventory screens.

Common use cases include saving supplier URLs where the product was found at a profitable price, noting reasons why a seemingly profitable product should be avoided (poor review trends, excessive return rates), flagging products for reordering when inventory depletes, or marking items that previously sold well but currently face oversaturation.

The notes field is searchable and exportable to Google Sheets, allowing sellers to build a personalized database of sourced products, failed opportunities, and products to monitor for future price drops. For VAs or sourcing teams, notes create shared institutional knowledge rather than isolated individual memories.

Quick View on Search Pages

When viewing Amazon search results, Seller Assistant App overlays key metrics on each product thumbnail without requiring sellers to open individual product pages. The quick view displays ASIN, BSR, product category, whether Amazon is a current seller, FBA seller count, FBM seller count, brand gate status, and any IP alerts.

This search-level filtering dramatically accelerates product evaluation. Sellers can scan 50 products in search results and immediately eliminate items with problematic indicators—Amazon competing as a seller, excessive FBA competition, IP alerts, or restrictions—before investing time in detailed analysis.

The quick view also allows liking/disliking products and adding brief notes directly from search results, creating a rapid triage system for initial sourcing sweeps.

Amazon Repricer Integration

Sellers using automated repricing software can push Seller Assistant App's calculated minimum prices (break-even, 10% ROI, 20% ROI) directly to their repricer as floor prices. This integration prevents repricers from engaging in race-to-the-bottom pricing wars that eliminate profitability.

The repricer receives product-specific minimum prices rather than account-wide percentage rules, allowing more precise margin protection across inventory with varying cost structures and competitive dynamics.

Multi-Marketplace Support

Seller Assistant App functions across all major Amazon marketplaces: US, UK, Canada, Germany, France, Italy, Spain, Japan, Australia, Mexico, and additional European markets. The extension automatically detects which marketplace you're viewing and adjusts fee calculations, currency, and VAT requirements accordingly.

For sellers operating across multiple markets, this eliminates the need for separate tools or manual fee structure adjustments. The profit calculator automatically applies the correct referral fee percentage (which varies by category and marketplace), currency conversion rates, and market-specific programs like Pan-European FBA storage.

Operation Without Seller Account

The extension offers a limited-feature mode for users without active Amazon Seller Accounts, useful for VAs conducting product research on behalf of clients or prospective sellers evaluating the business model before committing to a Professional Seller subscription.

Without account integration, users retain access to the FBA calculator, Keepa charts, stock checker, IP alerts, and export functionality. Features requiring account-specific data—profit estimator and brand gate checker—remain unavailable until a Seller Account is connected.

Seller Assistant App Pricing

Seller Assistant App operates on a monthly subscription model with three tiers. The Starter plan ($19/month) provides core functionality including the FBA calculator, Keepa integration, restrictions checker, and export to Google Sheets with a limit of 100 exports per month. This tier suits sellers evaluating 2-3 sourcing opportunities daily or those beginning online arbitrage operations.

The Professional plan ($39/month) removes export limits and adds the profit estimator, competitor stock checker, advanced IP alerts, and repricer integration. This tier targets active arbitrage sellers processing 20+ sourcing decisions per day who require unrestricted data export and competitive intelligence features.

The Business plan ($69/month) includes all Professional features plus priority support, team account capabilities for multiple users, and API access for custom integrations. This tier serves sourcing companies, VA teams, or high-volume operations managing shared product pipelines across multiple team members.

Annual subscriptions receive a 20% discount across all tiers. The company offers a 7-day free trial with full access to Professional plan features, allowing sellers to test the complete functionality before committing to a paid subscription.

Compared to competing extensions, Seller Assistant App's pricing sits in the mid-range. Tools like Keepa alone cost $19/month for data access, while comprehensive suites from companies like Jungle Scout or Helium 10 run $79-$99/month. Seller Assistant App's value proposition centers on integrating multiple discrete functions—calculator, IP database, stock checker, restrictions—that would otherwise require separate subscriptions or manual checking.

How Accurate Are the Fee Estimates

Seller Assistant App pulls fee data directly from Amazon's current fee schedules via API integration, ensuring referral fees and FBA fulfillment fees match what Amazon actually charges. The system updates automatically when Amazon adjusts fee structures, which typically occurs during Q4 fee schedule revisions.

Testing across product categories showed fee calculations matching Amazon's Revenue Calculator within $0.01-0.03 for standard-size items. Discrepancies occasionally appear for oversized products where dimensional weight calculations require precise measurements. The extension uses product dimensions listed in the Amazon catalog, which sometimes differ from actual measured dimensions after repackaging. Sellers should verify dimensions for oversized items where minor measurement differences significantly impact fees.

Storage fee estimates accurately reflect monthly costs but cannot predict long-term storage fees for individual units, which depend on how long specific inventory remains unsold. The calculator provides monthly storage costs based on current rates and product dimensions, but sellers must separately track inventory age to anticipate long-term storage assessments.

The calculator's optional fields for sales tax on COGS, VAT, and 3PL costs depend on seller-provided inputs. Accuracy here requires sellers to understand their actual tax obligations and prep costs. The tool provides the calculation framework but cannot automatically determine a seller's specific tax situation or negotiated prep center rates.

Overall, fee estimates provide reliable decision-making data for sourcing evaluation. For final margin validation before large purchases, cross-referencing with Amazon's native Revenue Calculator remains advisable, particularly for products with unusual dimensional characteristics or special fulfillment requirements.

Final Thoughts

Seller Assistant App delivers meaningful workflow efficiency for Amazon sellers who evaluate dozens of products daily. The primary value lies in consolidation—combining profit calculation, competitor intelligence, historical data, and restriction checking in a single interface eliminates the tab-juggling and manual calculation that slows sourcing operations.

The tool particularly benefits online arbitrage sellers who source from retail websites and need rapid go/no-go decisions on potential opportunities. The IP alert system and restrictions checker provide risk mitigation that purely financial calculators miss. A product showing 35% ROI becomes a poor investment if IP alerts indicate a high-risk brand or restrictions prevent listing.

The profit estimator distinguishes Seller Assistant App from simpler calculator extensions. Rather than just determining if a product is currently profitable, the estimator projects whether sufficient sales velocity exists to justify inventory investment. This forward-looking analysis prevents capital from becoming trapped in slow-moving inventory that meets margin targets but fails velocity requirements.

Limitations exist. The extension cannot predict future competitive changes—a product with minimal competition today may attract 20 new sellers next month. IP alerts flag historical issues but cannot guarantee future safety. The tool provides data for decision-making but doesn't replace seller judgment about market trends, seasonality, or brand relationships.

For sellers processing 15+ sourcing evaluations daily, the Professional plan ($39/month) likely pays for itself through time savings and improved decision accuracy. The combined value of unlimited exports, profit estimation, and stock checking exceeds the cost of subscribing to multiple single-function tools. Sellers evaluating fewer products may find the Starter plan sufficient, though the 100-export limit becomes restrictive during intensive sourcing sessions.

The extension complements rather than replaces comprehensive product research tools. Services like Jungle Scout or Helium 10 offer deeper market analysis, keyword research, and product opportunity databases. Seller Assistant App excels at rapid evaluation of already-identified opportunities rather than initial product discovery. The ideal workflow combines market research tools for opportunity identification with Seller Assistant App for efficient validation and margin analysis of specific products.

Seller Assistant App represents a solid investment for active Amazon arbitrage and wholesale operations where rapid, accurate sourcing decisions directly impact profitability and inventory efficiency.