If you’re trying to figure out which A/B testing agency is the right fit for your business, this is for you. Choosing the right partner isn’t just about who can run tests. It’s about who can deliver the kind of wins that grow your revenue, save you wasted ad spend, and give you confidence in your marketing. The right agency becomes an extension of your team, bringing expertise that translates directly into measurable business growth.
Here’s a breakdown of eight agencies you can look into, what makes each one different, and the results they’ve delivered for companies like yours. Each has been carefully vetted based on proven track records, transparent case studies, and real-world performance across diverse industries.
How We Chose These Agencies
You might be wondering how I built this list. I didn’t just grab names at random. I focused on agencies that show proof with numbers, not just pretty websites. That means real case studies, clear lift percentages, and brands you’ve probably heard of. I also looked at their strengths. Some shine at enterprise-scale programs, some specialize in landing pages, and others balance design with data.
Location and background mattered too, since knowing where a team is based and how they got started gives you context on how they work. Finally, I weighed the diversity of industries. You’ll see examples from SaaS, ecommerce, finance, consumer goods, and more. That way, no matter your field, you can spot an agency with experience close to yours.
Here’s the list:
1. Spiralyze
If you want a partner that only wins when you win, Spiralyze is it. Based in Atlanta, they don’t charge you a dime unless they increase your conversions. Their secret weapon is a prediction engine trained on insights from over 78,000 A/B tests. That means they already know what kinds of changes tend to deliver results.
You don’t have to juggle multiple vendors either. Spiralyze handles research, design, copy, coding, and development all in-house. Most clients see at least a 30% bump in conversions within 90 days.
Results you can expect:
- Okta: Doubled demo requests and drove a 90% lift on a pricing page CTA.
- Progress Software: 125% increase in demo request submissions from a hero redesign.
- Five9: Built an experimentation program that delivered consistent quarterly uplifts.
- CrowdStrike: Improved lead-gen flow and boosted enterprise conversions by double digits.
2. SplitBase
If you’re in e-commerce, SplitBase is a strong choice. Based in Montreal, they specialize in optimizing Shopify and DTC brands with a focus on conversion copywriting and design. They dig into your analytics, survey your customers, and then build experiments that connect messaging with buyer psychology.
Results you can expect:
- Dr. Squatch: Lifted conversions through landing page redesigns and clearer messaging.
- L’Oréal: Improved online purchase funnel with targeted tests.
- Kiehl’s: Higher add-to-cart rates after optimizing product detail pages.
3. GrowthHit
GrowthHit, headquartered in Seattle, blends CRO with growth marketing. They focus on startups and fast-growing brands that need both experimentation and performance marketing under one roof. If you want a team that can test everything from your funnel to your ads, this is a good fit.
Results you can expect:
- Universal Standard: 52% increase in ecommerce sales from funnel experiments.
- Custom Ink: Improved lead generation with redesigned landing pages.
- Prezi: Boosted paid signups through iterative pricing page tests.
4. KlientBoost
KlientBoost out of Costa Mesa, California, is known for its PPC and paid social expertise, but its CRO team is equally strong. They’re a great pick if most of your conversions come from paid ads and you want to maximize return.
Results you can expect:
- Airbnb (host acquisition campaigns): Lifted signups with optimized landing flows.
- Segment: Higher demo requests from SaaS-focused funnel experiments.
- SAP: Increased enterprise leads through improved ad-to-landing experiences.
5. Linear Design
Linear Design is a boutique CRO agency with a reputation for design-driven testing. Based in the US, they work with SaaS and ecommerce brands looking for clean, conversion-focused design backed by testing.
Results you can expect:
- Heap Analytics: 33% increase in demo requests.
- Zenefits: Improved onboarding completion through UX and copy tests.
- Remrise: Higher subscription signups with a revamped funnel.
6. Speero
Speero, founded by Peep Laja (also founder of CXL), focuses on structured experimentation programs for enterprise companies. With roots in Estonia and operations in the US, they bring a mix of European process and American scale.
Results you can expect:
- Procter & Gamble: Optimized multinational brand funnels.
- MongoDB: Lifted trial-to-paid conversions.
- ADP: Higher lead quality through funnel research and testing.
7. Cro Metrics
Cro Metrics, based in California, is known for embedding with product and marketing teams to run continuous testing. They’ve worked across SaaS, media, and nonprofits, making them versatile.
Results you can expect:
- GoFundMe: Lifted donations by improving trust signals and form flows.
- Twitch: Increased engagement with targeted UX experiments.
- Microsoft: Improved B2B product adoption through funnel optimizations.
8. Trinity Insight (Now Outerbox)
Trinity Insight, headquartered in Philadelphia, focuses on e-commerce brands. They combine CRO with analytics and personalization. If you’re a retailer or DTC brand, they bring deep experience in that space.
Results you can expect:
- PetSmart: Higher online purchases after checkout experiments.
- National Geographic Store: Increased order completions with streamlined UX.
- Adidas: Better engagement and conversion with redesigned product pages.
Summary Table
Don’t have the time to go back? Here’s a summary to help you decide.
| Rank | Company Name | Best Known For | Known Clients |
| 1 | Spiralyze | Performance-based pricing, in-house execution, Predictive CRO | Okta, Progress Software, Five9, CrowdStrike |
| 2 | SplitBase | Ecommerce and Shopify optimization | Dr. Squatch, L’Oréal, Kiehl’s |
| 3 | GrowthHit | Growth marketing plus CRO | Universal Standard, Custom Ink, Prezi |
| 4 | KlientBoost | Paid traffic conversion optimization | Airbnb, Segment, SAP |
| 5 | Linear Design | Design-driven CRO | Heap Analytics, Zenefits, Remrise |
| 6 | Speero | Structured enterprise experimentation | Procter & Gamble, MongoDB, ADP |
| 7 | Cro Metrics | Embedded CRO programs | GoFundMe, Twitch, Microsoft |
| 8 | Trinity Insight (Now Outerbox) | Ecommerce-focused CRO and analytics | PetSmart, National Geographic Store, Adidas |
Conclusion
If you’re serious about growing through experimentation, one of these agencies can help you get there. Spiralyze is great if you want a partner who only gets paid when you win. SplitBase is a smart choice if you’re running a DTC brand. GrowthHit or KlientBoost could be a fit if you’re heavy on paid acquisition. And agencies like Speero or Cro Metrics shine for enterprise or continuous testing.
Pick the one that fits your goals, your budget, and how you like to work. And always ask for case studies with numbers. That way, you’ll know they can deliver the kind of results you’re looking for.
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Daniel Raymond, a project manager with over 20 years of experience, is the former CEO of a successful software company called Websystems. With a strong background in managing complex projects, he applied his expertise to develop AceProject.com and Bridge24.com, innovative project management tools designed to streamline processes and improve productivity. Throughout his career, Daniel has consistently demonstrated a commitment to excellence and a passion for empowering teams to achieve their goals.