Last Updated: September 16, 2024
Our staff recently conducted an analysis of the largest B2B SEO agencies in the United States. While being the largest agency is no indication of being the best, the size of a B2B SEO agency implies a track record of success. It also correlates with economies of scale, in which specialists in multiple facets of B2B SEO are likely to be on staff to support the breadth of the agency’s client base; thus, if you have a conversion optimization or UX design need, for example, there will be an expert available.
The table below lists the top 8 largest B2B SEO agencies in the US, with the criteria being that the firm has greater than $10M in revenue and/or 100 employees—both of which correlate with an established professional services business that has a quality product. We also consider each firm’s notable clients, leadership, employee tenure, client review, and specialties.
The Largest B2B SEO Agencies In The US – 2024
| Rank | Company | Established | Founder Led | Leadership Experience Score | Average Review Score | Median Employee Tenure | Notable Clients | Specialty |
| 1 | First Page Sage | 2009 | Yes | 5.0 | 4.9 | 4.3 years | Salesforce, Logitech, US Bank | Thought Leadership-based SEO |
| 2 | Duffy Agency | 2009 | Yes | 4.8 | 4.6 | No data | Cavidi, the UN World Food Programme | International & Multilingual SEO |
| 3 | Marketing Eye | 2004 | Yes | 4.0 | 4.4 | 7.1 years | Safeway, Denticare, Cirrus Networks | Technical SEO & Web Design |
| 4 | Clay Agency | 2016 | Yes | 4.4 | 4.6 | 2.4 years | Slack, Coinbase, UPS | Conversion Rate and UX Optimization for SEO |
| 5 | Epsilon | 1969 | No | 4.7 | 4.3 | 4.6 years | Walgreens, Coach, Volvo | Full-Service Enterprise Marketing |
| 6 | Community Boost | 2012 | Yes | 4.1 | 4.6 | 1.9 years | The Trevor Project, The Humane Society, Seniors At Home. | SEO for Nonprofits |
| 7 | AMP Agency | 1995 | No | 4.5 | 4.6 | 2.8 years | Microsoft, Vizio, Asus | Video SEO |
| 8 | Metric Theory | 2012 | Yes | 4.3 | 4.6 | 3.1 years | GoFundMe, Lyft, LexisNexis | SEO & Paid Search |
The Largest B2B SEO Agencies in the US, Summarized
For Thought Leadership & SEO – First Page Sage
First Page Sage is the largest B2B SEO agency in the US. Their approach prioritizes publishing thought leadership content rather than standard SEO content, and requires a longer alignment period than most SEO agencies as they learn their client’s brand.
First Page Sage describes their campaign process as beginning with a dedicated team interviewing subject matter experts, studying the client’s market, and publishing several pages of new content on a weekly basis. Most of First Page Sage’s listed clients are in technical B2B industries such as SaaS, healthcare, and manufacturing, with notable clients including Salesforce, Logitech, and US Bank.
- Year Founded: 2009
- Headquarters: San Francisco, CA
- Services: Thought Leadership-based SEO, SEO Strategy Consulting, Conversion Optimization
| Summary of Online Reviews |
| First Page Sage uses “an in-depth onboarding process” in order to create “excellent content” that supports their “heavy focus on ROI and lead generation”, but some customers find that their focus on excellence requires a longer alignment period. |
For International SEO – Duffy Agency
The Duffy Agency specializes in international and multilingual SEO. They specialize in working with aspiring international brands to develop marketing strategies that target markets in multiple countries and languages.
SEO requires developing a working knowledge of the technical jargon and language that signals expertise to buyers, and international SEO is no different. The Duffy Agency works with their clients to translate nuanced industry knowledge into various languages to make content tailored for each target market. Their clients have included Cavidi and the UN World Food Programme.
- Year Founded: 2009
- Headquarters: Dover, NH
- Services: International SEO, Multilingual SEO
| Summary of Online Reviews |
| Duffy Agency targets “ambitious” goals for their services but often succeed “without increasing campaign cost“. While their results must “build over time“, they are “dramatic“. |
For Technical SEO – Marketing Eye
Marketing Eye is a creative marketing services firm based out of Atlanta, GA, that focuses on the technical and web design aspects of SEO.
Unlike other marketing agencies that offer total content production, Marketing Eye looks to optimize existing content for keyword relevancy and search intent. This makes them a good fit for companies that already have strong in-house content teams but lack SEO or technical expertise, and their clients have included Safeway, Cirrus Networks, and Denticare.
- Year Founded: 2004
- Headquarters: Atlanta, GA
- Services: Marketing Automation, Marketing Consulting, Web Development
| Summary of Online Reviews |
| Marketing Eye’s team are both “competent and professional” despite sometimes needing “additional training.” Nevertheless, their service is “superior“. |
For UX and Conversion Optimization – Clay Agency
Clay Agency was founded in 2016, and they’re the youngest agency on this list. They place their focus squarely on the difficult process of conversion rate and UX optimization, and increasing conversion rates of organic visitors.
SEO requires conversion optimization to be effective: organic traffic is only as valuable when it converts into actual sales leads. Clay Agency is a good fit for companies that have strong organic traffic numbers but struggle with their conversion rates. Their clients have included Slack, Coinbase, and UPS.
- Year Founded: 2016
- Headquarters: San Francisco, CA
- Services: UI/UX design, Product & Brand Strategy, Conversion Rate Optimization.
| Summary of Online Reviews |
| Clay Agency’s design focus is “high-quality“ and they deliver their services at a “great price“. Their teams pay “close attention to detail” for branding focused clients. |
For Enterprises – Epsilon
Epsilon is a full-service enterprise marketing company that combines traditional and digital marketing into a single campaign. They specialize in working with enterprise companies, and the strategic demands unique to enterprise SEO.
Because enterprises often have complex vendor vetting and setup processes, they often need a single agency to handle all of their marketing needs. Epsilon is capable of uniting disparate marketing channels under one roof, and their past clients include Walgreens, Coach, and Volvo.
- Year Founded: 1969
- Headquarters: Irving, TX
- Services: Digital Media, Data Solutions, Customer Insights
| Summary of Online Reviews |
| Epsilon’s teams are “attentive” and “responsive” to enterprise clients needs, and customers report that their “very costly” pricing is made up for by strong results. |
For Nonprofits – Community Boost
The San Diego-based Community Boost offers a full suite of digital marketing services for nonprofits and charitable organizations, with SEO as one of their core services. The inherent trust that visitors confer on websites appearing in organic search results is particularly important for nonprofits, particularly when seeking donations from high net worth individuals and corporate sponsors.
Agencies that specialize in this niche—and are therefore familiar with the tone and SEO strategies most effective for nonprofits to use—are relatively rare. Community Boost is the largest agency among them, and their past clients include The Trevor Project, The Humane Society, and Seniors At Home.
- Year Founded: 2012
- Headquarters: San Diego, CA
- Services: SEO for Nonprofits, Youtube & Display Ad Management, Google Ad Grant Management
| Summary of Online Reviews |
| While teams are “dedicated to their craft” and Community Boost is an “incredible partner” for nonprofits, their processes still have “small tweaks to iron out” despite their relatively long tenure. |
For Video SEO – AMP Agency
AMP Agency is a full-service digital marketing agency, with video SEO being a major focus. They help companies optimize video titles and descriptions to drive views and engagement, optimizing for YouTube’s unique algorithm.
AMP is a good fit for companies that attract customers primarily through their video content. Their clients have included Microsoft, Vizio, and Asus.
- Year Founded: 1995
- Headquarters: Boston, MA
- Services: Video SEO, Integrated Media Strategy, Digital Experience Design & Development
| Summary of Online Reviews |
| AMP Agency creates “collaborative” relationships with their clients, providing teams that are “efficient, straightforward, and persistent“, but sometimes “small things get missed“. |
For SEO & Paid Search – Metric Theory
Metric Theory was founded in 2012 and focuses on combining SEO with paid search and remarketing. By tracking your visitors, they can help you optimize your ad spend by displaying ads only to prospects who have found your website organically.
Despite its high ROI, SEO’s relatively long time frame before results are seen can be off putting for many marketing teams. Paid advertising is a useful way to bridge this gap, lowering the overall average ROI of marketing efforts for increased short term lead generation. Metric Theory is a good fit for companies who need short-term lead generation over long-term ROI, and their clients have included GoFundMe, Lyft, and LexisNexis.
- Year Founded: 2012
- Headquarters: San Francisco, CA
- Services: SEO, Paid Search, Remarketing & Display Ads
| Summary of Online Reviews |
| Metric Theory conducts “thorough background research” and are “effective at capitalizing on revenue sources“, but teams would “benefit from having more resources“. |
The Top B2B SEO Agencies in the US, by Industry
Our team has researched the top SEO agencies for each of the following industries:
The full reports may be found in the links above, and the top 5 agencies for each industry, as well as their industry reputation score, are listed below:
The Top SaaS SEO Agencies of 2024
| Rank | Agency | Industry Reputation Score |
| 1 | First Page Sage | 4.9 |
| 2 | REQ | 4.9 |
| 3 | Clay Agency | 4.7 |
| 4 | Epsilon | 4.5 |
| 5 | Marketing Eye | 4.4 |
The Top Manufacturing SEO Agencies of 2024
| Rank | Agency | Industry Reputation Score |
| 1 | First Page Sage | 4.8 |
| 2 | Kula Partners | 4.8 |
| 3 | Industrial Strength Marketing | 4.6 |
| 4 | Windmill Strategy | 4.5 |
| 5 | Factory Web Source | 4.4 |
The Top Real Estate SEO Agencies of 2024
| Rank | Agency | Industry Reputation Score |
| 1 | REQ | 5.0 |
| 2 | First Page Sage | 5.0 |
| 3 | Portal Ventures | 4.8 |
| 4 | ReachLocal | 4.7 |
| 5 | Jives Media | 4.6 |
The Top Healthcare SEO Agencies of 2024
| Rank | Agency | Industry Reputation Score |
| 1 | RNO1 | 4.9 |
| 2 | First Page Sage | 4.9 |
| 3 | k2md Health | 4.7 |
| 4 | REQ | 4.6 |
| 5 | iHealthSpot | 4.4 |
The Top Fintech SEO Agencies of 2024
| Rank | Agency | Industry Reputation Score |
| 1 | First Page Sage | 5.0 |
| 2 | Yes& Agency | 4.9 |
| 3 | TOP Agency | 4.8 |
| 4 | CSTMR | 4.5 |
| 5 | Banktastic | 4.5 |
