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The Largest SEO Companies in the U.S. in 2024

SEO Blog
Top Seo Companies In Us

Last Updated: December 29, 2023

Company size may not be the first factor you consider when it comes to choosing an SEO agency to work with, but it’s an indicator that a company is successful, well managed, and has the resources to make your campaign successful. Often, firms that describe themselves as “SEO agencies” are small 1–5 person companies that are able to provide technical advice and backend updates, but don’t have the staff necessary to manage a multi-faceted campaign. A firm that’s among the largest in the US will necessarily have a proven track record and be a reliable option for businesses looking to outsource their SEO.

In addition to ranking SEO agencies by size, our team also conducted a meta analysis of the agencies’ online reviews in order to produce an overall average. We included reviews from Clutch, G2, Upcity, Sitejabber, Capterra, and Google in our dataset, weighting “pure” review sites that do not solicit payment from agencies for inclusion over those with a more commercial focus.

Finally, because SEO is such a wide field, we’ve separated our list into 10 different niches. We’ve chosen to only list companies that have a laser focus on their particular niche of SEO rather than simply creating a list of the largest digital marketing companies that happen to offer SEO.

The Largest SEO Companies In The U.S. in 2024

COMPANY HEADQUARTERS SPECIALTY AVERAGE REVIEWS
1 First Page Sage San Francisco, CA Thought leadership-based SEO, content marketing, lead generation 4.6
2 Duffy Agency Dover, NH International SEO, multilingual content marketing 4.5
3 Boostability Lehi, UT White label SEO 4.3
4 LocaliQ Woodland Hills, CA Local SEO, Google Business Profile optimization 3.9
5 Epsilon Irving, TX Enterprise digital marketing, traditional marketing 4.0
6 Seller Interactive Markham, ON Amazon SEO & account management for Amazon eCommerce companies 4.4
7 Aumcore New York, NY Voice and mobile search SEO 4.7
8 Clay Agency San Francisco, CA Conversion rate optimization for SEO, UI/UX design, web design  4.6
9 Marketing Eye Atlanta, GA Technical SEO, web design 3.9
10 Community Boost Bethesda, MD Nonprofit SEO  4.6

For Thought Leadership-Based SEO – First Page Sage

First Page Sage is the largest overall SEO firm in the US, having attained its growth from continual specialization within the field of SEO, as opposed to the more typical agency trajectory of expanding horizontally into other marketing services.

The firm’s strength is combining SEO and thought leadership—a high quality form of content marketing—to turn its clients’ websites into Google-trusted industry resources, essentially automating lead generation for them. The majority of its clients are in technical B2B industries such as SaaS, IT, and manufacturing, with clients including Cadence Design Systems, Logitech, and US Bank; however they also work with a number of large B2C businesses such as Chanel, Nerdwallet, and Wix.

Their campaigns are comprehensive, consisting of SEO strategy, keyword research, technical SEO, content marketing, analytics, marketing attribution, and detailed reporting.

Location: San Francisco, CA
Founded: 2009
Price Range: $$$
Average Review Score: 
4.6
Services: SEO, Content Marketing, Web Design

Summary of Online Reviews
First Page Sage prioritizes “excellent content” which leads to “provable lead generation and ROI”; but their results require “an in-depth onboarding period” that can take longer than that of firms that focus on paid marketing.

For White Label SEO – Boostability

Due to SEO’s demanding nature and the specialized skillset required, digital marketing agencies often find themselves in need of additional support to help manage clients’ SEO campaigns. Many SEO agencies are happy to act as a white label partner, but few make it their specialty. Boostability is the largest SEO firm that specializes in providing white label services to other marketing agencies, partnering with digital marketing agencies that don’t have the resources to offer SEO on their own.

Boostability has also worked directly with small businesses. They offer low-cost packages that are designed specifically for companies that are just getting started, are in low-competition markets, and not yet ready to post blog content regularly. They also provide solutions for scaling businesses, so they can grow with their clients. Clients of Boostability include Bloom Studios, KIARO Computer Solutions, and Peterson Family Orthodontics.

Location: Lehi, UT
Founded: 2009
Price Range: $
Average Review Score: 
4.3
Services: White Label SEO, Small Business SEO, Web Design

Summary of Online Reviews
Boostability is “professional and knowledgeable“, and their representatives are “eager to help” and “responsive” but they suffer from “too much account manager turnover“.

For Multilingual SEO – Duffy Agency

Multilingual SEO is a difficult practice: as if translation weren’t enough of a nuanced process, when you add keyword strategy and deciphering search intent to the mix, it becomes even more complex. Duffy agency has been successful at doing all that, including in a few more technical markets where an understanding of specialized jargon matters.

Duffy specializes in providing SEO, online marketing, and social media marketing services to companies who have brands with international reach. They’ve worked with clients in fields ranging from Consumer Foods to Medical Services, and their past clients include Napapijri, Cavidi, and the United Nations World Food Programme.

Location: Dover, NH
Founded: 2009
Price Range: $$$$
Average Review Score:
 4.5
Services: International SEO, Strategic Consulting, Online Brand Management

Summary of Online Reviews
Duffy Agency services are “ambitious“, but manage to find success “without increasing campaign cost“. Their results are often “quite good“, but must “build over a long period of time“.

For Local SEO – LocaliQ

Not all companies need to compete nationally. A construction firm based in a single city, for instance, will gain nothing from being seen by searchers across the country. Instead, they can focus all of their efforts on geotargeted keywords, which are both lower competition and much more likely to lead to a sale.

LocaliQ (formerly ReachLocal) is the largest SEO agency with a focus on increasing local search visibility. They specialize in working with inherently location-bound companies in industries such as real estate, home services, and automotive sales and service, and their clients have included TGM Associates, Mr. Rooter, and Central Washington University.

Location: Woodland Hills, CA
Founded: 2004
Price Range: $$
Average Review Score:
3.9
Services Offered: Local SEO, PPC Marketing, Marketing Automation

Summary of Online Reviews
LocaliQ is a “great asset” to their clients, offering “exceptional web design” and digital media services. Some former clients report “missed deadlines” and poorly optimized PPC campaigns however.

For Amazon SEO – Seller Interactive

Google accounts for over 90% of all general search engine traffic, which is why nearly all SEO agencies dedicate themselves to understanding the nuances of Google’s algorithm. But for many B2C eCommerce companies, making it to the top of Amazon’s search results is just as important as reaching the first page of Google and requires a partner that understands not just Amazon’s search algorithm, but can also help manage their clients’ Amazon marketplace and listings.

As of 2023, Seller Interactive is the largest Amazon-focused SEO agency in the US. They’ve been helping businesses manage their AMS accounts since 2012, and have had particular success partnering with companies in the consumer technology, food &  beverage, and cosmetics industries.

Location: Markham, Ontario
Founded: 2012
Price Range: $$
Average Review Score:
4.4
Services Offered: Amazon SEO, Amazon Account Management, Demand-Side Platform Advertising (DSP)

Summary of Online Reviews
Seller Interactive is “knowledgeable of Amazon processes” and their clients are “impressed with the quality of their work“, which tends to “exceed expectations” even if “communication can sometimes be difficult“.

For Full-Service Enterprise Digital Marketing – Epsilon

Enterprises not only need to ensure that their marketing partner is familiar with enterprise-specific SEO strategies, but because of their size and entrenched processes, often find that they need to find a single agency to handle all of their digital marketing. Attempting to contract with multiple agencies often leads to internal enterprise purchasing processes delaying campaigns, which can result in lowered ROI and poorly coordinated marketing pushes.

Epsilon combines SEO, personalized messaging, and customer data platforms to give enterprises a single-provider option for all of their digital marketing needs. They’re particularly successful in their work with global consumer brands, and their past clients include Walgreens, Coach, and Volvo.

Location: Irving, TX
Founded: 1969
Price Range: $$$
Average Review Score: 
4.0
Services Offered: Digital Media, Data Solutions, Customer Insights

Summary of Online Reviews
Epsilon is “responsive to feedback” and provides “attentive project oversight” for their clients, but their services “are very costly.”

For Technical SEO – Marketing Eye

Not all businesses need an SEO agency to write top tier content for them. If producing content is already a core part of their business model, they should look to their SEO agency to provide conversion-optimized website design, technical SEO, and strategy.

Marketing Eye offers a broad range of marketing services, but their strength is in their technical and strategic consulting. Their 15 years of experience has seen them work with clients in consumer goods, logistics, and financial services, counting Botani, Star Source Pty. Ltd., and Mint Money among their clients.

Location: Atlanta, GA
Founded: 2004
Price Range: $$
Average Review Score: 
3.9
Services Offered: Marketing Automation, Marketing Consulting, Web Development

Summary of Online Reviews
Clients report that Marketing Eye  is “competent and professional” with “superior” service offerings, but employees report needing “additional training.”

For Conversion Rate Optimization – Clay Agency

Conversion rate optimization is a difficult skill to find in an agency; while many companies mention it on their website, few treat it as an art. Because CRO is a mixture of web design, UI/UX design, and analytics, an SEO agency that is strong in this area will naturally have dedicated UI/UX and analytics experts on staff.

Clay Agency places their focus squarely on digital strategy and UI/UX design, making them a good fit for clients whose primary SEO need is improving their conversion rate from organic visitors. Their service involves considerable online research and detailed UI/UX audits.

Location: San Francisco, CA
Founded: 2016
Price Range: $$$
Average Review Score: 
4.6
Services Offered: UI/UX Design, Product and Brand Strategy

Summary of Online Reviews
Delivering “top-notch quality” at a “competitive price“, Clay Agency pays “close attention to detail” and provides “high-quality design.”

For Voice Search Optimization – Aumcore

Second only to AI-based search, voice search is the newest SEO niche, and is growing in importance as users begin to rely more and more on Siri, Alexa, and Google Assistant. This user segment is of particular importance for B2C companies, as the natural language processing technologies used in those assistants are currently optimized for everyday, non-technical speech. Aumcore includes Voice SEO as one of their core services, and understands that keyword targeting strategies are fundamentally different for spoken and typed language.

More important than this new niche, however, is mobile search. Google has officially completed their transition to mobile-first indexing, and over half of all web traffic is accessed from mobile devices. Prioritizing mobile users is especially important for B2C companies, as consumers are more likely to be browsing on their phone than professional users. Aumcore is experienced with working with both types of businesses, and their clients have included Comodo Cybersecurity, eviCore, and Delonghi.

Headquarters: New York, NY
Founded: 2010
Price Range: $$
Average Review Score:
4.7
Services Offered: Voice Search Optimization, Social Media, Brand Strategy

Summary of Online Reviews
Aumcore’s work is “excellent“,  and they boast a “well-rounded and responsive team“.

For Nonprofits & Charities – Community Boost

Nonprofits and charitable organizations can benefit just as much from SEO as for-profit businesses. The inherent trust that searchers afford to organic search results is just as—if not more—important for nonprofits, who are seeking donations from difficult-to-reach high net worth individuals and sponsors.

As this is a smaller niche, SEO companies that fall into this category are relatively rare and the largest we’ve found is Community Boost. While Community Boost offers a suite of digital marketing services, SEO is one of their core services.

Headquarters: San Diego, CA
Founded: 2012
Price Range: $$
Average Review Score: 
4.6
Services Offered: Nonprofit SEO, Youtube & Display Ads, Google Ad Grant Management

Summary of Online Reviews
Community Boost is “dedicated to their craft” and is an “incredible partner” for nonprofits, but still has “small tweaks to iron out“.

The Top SEO Agencies in the US by Industry

Our team also ranked the top SEO agencies in the US based on industry specialty. In doing so, we considered average review score; notable clients; # of employees; and the quality of the firm’s leadership team. We were able to compile data in the following 6 industries:

The Top SaaS SEO Agencies
# Name Clients
1 First Page Sage Salesforce, Verisign, Cadence Design Systems
2 REQ Katabat, Verint, ActiveNav
3 Clay Agency Slack, Zenefits, Hint
4 Epsilon CDW, Faraday
5 Marketing Eye Construx Solutions, Innovent CRM, JESI
The Top Financial SEO Agencies
# Name Clients
1 TOP Agency Discover, Fidelity Investments, Oppenheimer Funds
2 Yes& Agency United Bank, Resources Global Professionals
3 First Page Sage US Bank, Credit Sesame, SoFi, defi Solutions
4 CSTMR Lending Tree, SELFi, Credit Karma
The Top Healthcare SEO Agencies
# Name Clients
1 RNO1 Healto, Fluxa
2 First Page Sage Dignity Health, City of Hope, Institute on Aging
3 k2md Health True Health, Lovelace Health System, UT Health
4 REQ Centene, Health Net, PhRMA
5 iHealthSpot The Centers for Advanced Orthopaedics
The Top Home Services SEO Agencies
# Name Clients
1 First Page Sage Orkin, Fortress Building Products, Rainbow Waterproofing
2 LeadHub Champion AC, Gotelli Plumbing, Window World
3 Lemonade Stand Rightime Home Services
4 C Squared Fiber Mortgage Group, RealtyTek
The Top Real Estate SEO Agencies
# Name Clients
1 REQ The Empire State Building, Golden Gate Hotel & Casino
2 First Page Sage Corcoran, Apollo Group, We Buy Ugly Houses
3 Portal Ventures RealAdvisor, Sidespace
4 ReachLocal CuliQuip, TGM Associates
5 Jives Media LBI Living, Gulf Living Group
The Top SEO Agencies for Manufacturers
# Name Clients
1 First Page Sage Swagelok, Tempo, Zetec
2 Kula Partners Emmerson Packaging, Essex Active, Reliable Automatic Sprinkler
3 Industrial Strength Marketing ExxonMobil, Sentry, UPS
4 Windmill Strategy Fast Test, Summit Engineered Automation

First Page Sage Staff