What does an ecommerce agency do? A buyer's guide to choosing one
Hiring an ecommerce agency is one of the biggest spending decisions a growing online brand makes. Get it right and you gain specialist skills you couldn’t afford to hire. Get it wrong and you lose months, budget and momentum.
This guide explains what ecommerce agencies actually do, the main types, when you need one (and when you don’t), and how to choose. It includes a scorecard you can use to compare agencies side by side.
What an ecommerce agency does
An ecommerce agency is a specialist firm that helps businesses sell online. Depending on its focus, it builds and improves online stores (design and development), drives traffic and sales (SEO, paid advertising, email and social), improves conversion rates, or does all of these as a full-service partner.
Unlike a general marketing agency, an ecommerce agency works with the specific mechanics of online retail: product catalogs and feeds, Shopping ads, cart and checkout behavior, inventory, repeat purchase and platform ecosystems such as Shopify and Magento.
Typical services include:
Store design and development: building, redesigning or replatforming your store
SEO: organic visibility for categories and products
Paid media: Google Shopping, search, Meta, TikTok and Amazon ads
Email and SMS: retention flows and campaigns
Conversion rate optimization (CRO): research and testing to lift sales from existing traffic
Strategy and analytics: growth planning, measurement and reporting
The main types of ecommerce agency
Here’s how the main types compare at a glance:
Store + marketing + CRO
Retainer, often plus projects
One accountable team
Uneven depth across disciplines
Paid, SEO, email, creative
Monthly retainer
Channel expertise
Can’t fix store-side problems
Builds, redesigns, integrations
Fixed-price projects + support
Technical depth
Little growth accountability
One channel or platform, deeply
Retainer or project
Deep expertise
You coordinate the pieces
Full-service growth agencies
One partner for both the store and the marketing. Best for brands that want a single accountable team and fewer hand-offs. Watch for agencies that are “full-service” in name but strong in only one area. Ask to see work in each discipline.
Marketing and performance agencies
Focused on traffic and revenue: paid media, SEO, email, sometimes creative. Best for brands whose store is in good shape and whose priority is growth.
Design and development agencies
Focused on building and maintaining the store. Best for launches, redesigns, replatforming and complex integrations.
Specialist channel and platform agencies
How agency engagements typically work
Most ecommerce agency relationships follow one of three models:
Project-based: a defined deliverable with a fixed price and timeline, such as a new store, a redesign, a migration or an audit. You know the cost up front; changes in scope cost extra.
Monthly retainer: ongoing work such as SEO, paid media, email or CRO, for an agreed monthly fee. Good retainers have a clear scope, a plan and agreed KPIs, not just “hours.”
Hybrid: a build project followed by a growth retainer, often with the same agency.
Do you need an agency?
You probably do if:
- you need specialist skills (technical SEO, feed management, Klaviyo, Shopify development) that wouldn't keep a full-time hire busy
- growth has stalled and you need an outside diagnosis
- you're launching or replatforming and need a team for a defined project
- You may not if:
- you're pre-revenue and still testing product-market fit, where founder-led marketing often teaches you more
- you already have a capable in-house team and only need occasional freelance help
- PHASE 2: when published, add: "For a fuller comparison, see our guide [comparing an agency with an in-house team."]
How to choose: a practical scorecard
Score each shortlisted agency from 1 (weak) to 5 (strong):
Type
Most clients are ecommerce brands like you
Relevant proof
Case studies with real numbers, from similar businesses
Platform expertise
Proven work on your platform (Shopify, Magento…)
Strategy before tactics
Asks about margins, CAC and LTV before pitching services
Reports on revenue, CAC and profit, not just traffic and ROAS
You meet the people who’ll actually do the work
Transparency
Clear pricing, contract terms and account ownership
Communication
Defined cadence, a named lead, responsive in your time zone
Understands your stage, market and constraints
How to use the scorecard
Score each agency independently, with at least two people from your team, then compare. Weight the criteria that matter most to you; for example, platform expertise matters more for a replatform than for an SEO retainer. Treat a score of 1 or 2 on “relevant proof” or “transparency” as a warning sign, however polished the pitch.
Questions to ask before you sign
1
Who exactly will work on our account, and what’s their experience?
2
3
4
5
Who owns our ad accounts, analytics, content and code?
6
What’s the contract term and notice period?
7
How do you price, and what’s not included?
8
Can we speak to two current clients?
Comparing common headless approaches
On the team: named people, with roles and relevant experience, and a clear statement of how much of their time your account gets
On measurement: business metrics first (revenue, new customers, CAC, contribution margin), with channel metrics underneath
On the first 90 days: a specific discovery process, quick wins and a plan they’ll commit to in writing
On ownership: “Everything is in your name, and we’re added as users”
On pricing: a clear scope of what’s included, what isn’t, and how changes are handled
Vague answers to any of these are worth probing before you sign.
Red flags
Guaranteed rankings or ROAS. Nobody controls Google or Meta.
Reporting that leads with impressions and clicks instead of revenue
You can’t meet the team before signing
Long lock-in contracts with no performance exit
The agency owns your ad accounts or analytics
No ecommerce-specific case studies
One-size-fits-all packages that ignore your margins and stage
How to run a fair agency selection
1
Write a short brief: your goals, current numbers, platform, budget range, timeline and what success looks like in 12 months.
2
Shortlist three to five agencies using referrals, directories such as Clutch, and agencies whose work you’ve seen.
3
4
Request proposals against the same brief, so you’re comparing like with like.
5
Score proposals with the scorecard above, involving at least two people.
6
Check references, ideally from clients who’ve worked with the agency for over a year, and one who left.
7
Agree a 90-day plan and review point before committing long term.
What it costs
Ecommerce agency pricing varies widely by service, scope and agency size. Marketing services are usually monthly retainers; builds are usually fixed-price projects; paid media management is often a percentage of ad spend or a flat fee. For typical US ranges and what drives them, read our pricing guide.
Contract terms to check
Term and notice: minimum commitment and how you can exit
Scope: exactly what’s included each month
Ownership: your accounts, data, creative and code belong to you
IP and confidentiality
Fees: setup fees, ad spend handling and pass-through costs
Performance reviews: scheduled checkpoints to reassess fit
Frequently asked questions
What’s the difference between an ecommerce agency and a digital marketing agency?
Should I hire one full-service agency or several specialists?
How long should I give an agency before judging results?
How much should I spend on an ecommerce agency?
Can I switch agencies without losing data?
Yes, if you own your accounts. Make sure your ad accounts, analytics, Merchant Center, email platform and store are registered to your business, with the agency added as a user, before you start.