Your brand shouldn’t just be different, it should also be antifragile.

GST Impulse Agency is an Amazon agency based in Solsona (Catalonia, Spain) that manages seller accounts for niche food, supplement and cosmetics brands: account setup and Brand Registry, listings, visual design, Amazon Ads, profitability and scaling. It is run by Guillem Sarri Testagorda, who has been selling on Amazon since 2021 and holds 8 official Amazon Ads Academy certifications.

Guillem Sarri Testagorda, the founder. He is a technical engineer by training and, before Amazon, was a production manager in manufacturing: project management, systems, shop-floor teams, processes, deadlines and quality control. He started selling on Amazon in 2021 with his own brands and his own money.

Yes. Guillem has been selling on Amazon since 2021 with his own brands: he has built two and a third is under construction. The same niche-differentiation approach he applies to clients is first tested on his own brand.

Only niche food, supplement and cosmetics brands. GST Impulse Agency currently manages 5 active brands on Amazon marketplaces in the European Union and the United States, including Korean facial skincare, dog supplements and cosmetics resale.

Because these categories have their own regulations and a very specific buyer. Specialising means knowing which claims Amazon allows and which ones get a listing taken down, and how someone shopping for collagen or a serum at 11 p.m. actually buys. A specialist doesn't learn the category on your account.

GST Impulse Agency is based in Solsona (Lleida, Catalonia) and works remotely with brands across Spain and with accounts on other European marketplaces such as Amazon.it. Day-to-day communication is via WhatsApp, email and phone calls.

Guillem himself. GST Impulse Agency is deliberately small: you talk to the person who reviews your numbers and runs your campaigns, with no intermediaries and no account-manager turnover.

Four rules: every figure shown comes from a report, none is made up; one client, one dataset, your numbers are never mixed with anyone else's; the target is set in month one and reviewed together every two months; and if a month goes badly, you're told so, with the cause and no spin. On top of that, the agency doesn't just manage: it differentiates the brand by niche so it's hard to copy.

Full Amazon account management across seven areas: account setup and Brand Registry; listing upload and optimisation; niche viability before investing; Amazon Ads managed to a TACoS target; ASIN-by-ASIN profitability down to real net margin; catalogue scaling and preparation for expansion or exit; and visual design (packaging, infographics, A+ Content and product photography).

Yes. GST Impulse Agency manages Sponsored Products, Sponsored Brands, Sponsored Display and video ads, always to a TACoS target rather than a spend target. It currently manages over €10,000 a month in Amazon Ads spend. Guillem is certified by Amazon Ads Academy in sponsored ads (including advanced), video, Amazon DSP, retail, campaign planning and Amazon Marketing Cloud.

Yes. GST Impulse Agency handles the visual side too, not just management: packaging, infographics, A+ Content and product photography. Each Sprint includes 9 listing images per product.

Yes. GST Impulse Agency uploads and optimises product listings built for conversion: title, bullet points, description, backend keywords and visual content. Each Sprint includes an SEO strategy for the product.

Yes. GST Impulse Agency sets up Amazon Seller and Vendor accounts and enrols the brand in Amazon Brand Registry to protect it from day one.

Yes. It is one of GST Impulse Agency's services: market analysis of the niche before investing, not after, to see whether there is demand, what the competition looks like and whether the margin can carry advertising.

Amazon marketplaces in the European Union and the United States. Active accounts include stores on Amazon.es and Amazon.it.

Yes, as part of account management: FBA shipments and inventory, which countries to enable in the Pan-European FBA programme and the registration numbers (such as EPR) that Amazon requires. The tax side, such as VAT registration in other countries, is handled by the brand's tax advisor; the agency prepares the Amazon data for them.

Yes. That's why the agency works only in these categories: knowing which claims Amazon allows on a supplement or cosmetic and which get a listing removed. It is not a substitute for legal advice, but it avoids the mistakes that take down the most listings.

Amazon Seller Central and the Amazon Ads console as data sources, sellerboard for real profitability per ASIN, and Helium 10 and SellerSprite for keyword and market research.

Yes. GST Impulse Agency scales catalogues in a structured way and prepares the account for expansion into new markets or for an exit, with per-ASIN numbers in order.

There are three ways to start with no long contracts: a free 20-minute strategy call; a 1-product Sprint for €149 (one-off: 9 listing images and a product SEO strategy); or a 3-product Sprint for €297 (27 images and SEO strategy for all 3, saving €150). If the result convinces you, you move on to full management.

The 1-product Sprint (€149) includes 9 listing images and the product's SEO strategy. The 3-product Sprint (€297) includes 9 images per product, 27 in total, and the SEO strategy for all 3. It is a one-off payment to try the agency's work before hiring full management.

It's 20 minutes in which Guillem looks at your Amazon account with you and tells you, with no obligation, the 3 things currently costing you sales. It's a real analysis, not a sales pitch.

No. GST Impulse Agency doesn't use long contracts: you can start with the free call or a one-off Sprint and decide, with the result in front of you, whether to continue with full management.

Esencia de Alda, premium Korean facial skincare on Amazon.es: between January and September 2026 TACoS fell from 28.9% to 18.22% and net margin went from -5.6% to 16.36%, with higher revenue. Best month: May, with a 17.7% net margin. Figures from the account's sellerboard reports.

Dognity, dog supplements on Amazon.es: between May and September 2026 TACoS fell from 24.3% to 13.03%. Net margin in those months doesn't yet reflect the work because of a product being removed from the catalogue, and the site says so plainly.

Natecos, resale of LEPO cosmetics on Amazon.it: from a baseline of around €3,400-3,600 a month to a peak of €9,138 in August 2026, while spending less on advertising, not more.

With the account's real reports: Seller Central, Amazon Ads and sellerboard for net margin per ASIN. The target is set in month one and reviewed with the client every two months. If something goes wrong, you're told, with the cause.

ACoS is ad spend divided by the sales attributed to advertising. TACoS (Total ACoS) is ad spend divided by the account's total sales, organic included. If TACoS falls while revenue rises, advertising is lifting organic sales: that's why GST Impulse Agency manages to a TACoS target.

There's no universal number: it depends on each product's margin. Break-even ACoS is the margin before advertising divided by the selling price; above it, every ad-driven sale loses money. That's why the target is calculated product by product using real costs.

It's Amazon's programme for owners of a trademark registered (or pending) with an accepted trademark office. It gives control over listing content, access to A+ Content, Sponsored Brands and the brand store, and tools to report copies and infringements.

A sub-niche is a specific customer, need or pain point within a broad category. Focusing a brand on a sub-niche makes it the go-to solution for that buyer, raises barriers to entry and makes it hard to copy, instead of competing on price alone.

It's enhanced content (images, comparison modules and designed text) shown on the product page below the description. It's available to brands in Brand Registry and usually helps conversion.

It's the programme where Amazon spreads your inventory across its warehouses in several EU countries to deliver faster in each one. Storing stock in a country can create VAT obligations there, so the countries are best decided together with a tax advisor.

It's almost always one of three things: lack of traffic (you don't show up in search or advertising isn't well targeted), low conversion (images, title or price that don't persuade) or a margin that can't carry advertising. On the free 20-minute call GST Impulse Agency reviews your account and tells you your 3 specific problems.

If you have time to learn advertising, SEO, logistics and regulations, you can do it yourself. A specialist agency pays off when every unoptimised month costs you more than the management fee, or when you don't know whether you really make money per product. That's why GST Impulse Agency lets you start with a free call or a one-off Sprint, so you can check before committing.

By WhatsApp at +34 639 467 280, by email at guillem@gstimpulse.com, or by booking the free 20-minute strategy call on gstimpulse.com.

Spanish, Catalan and English.