A conversion rate optimization (CRO) agency is a marketing agency that specializes in improving a website's ability to turn visitors into customers or leads. It focuses on increasing conversion rates for its clients.

A CRO agency helps increase website conversions by analyzing user behavior and adjusting the site to increase the percentage of visitors who complete a desired action, such as purchasing or signing up for a newsletter.

CRO services are most valuable for eCommerce stores, SaaS platforms, financial services, and subscription-based businesses, where even the smallest conversion lifts directly increase revenue.

They also benefit B2B companies with high-value leads, such as legal, healthcare, and enterprise tech, where optimizing forms, landing pages, and funnels boosts qualified lead generation and lowers acquisition costs.

Top-rated CRO agencies on DesignRush in 2025 are:

1. Invesp
2. Northpeak
3. SiteTuners
4. SplitBase
5. PurpleFire
6. Experiment Zone
7. Conversion Sciences
8. NoGood
9. Conversion
10. Media Contour

Conversion rate optimization companies offer services including:

• CRO audit
• CRO strategy development
• A/B testing
• Landing pages optimization
• Website audit and optimization
• Heat mapping
• Visitor analytics and reporting

Specialized CRO services:

• Personalization and segmentation
• Mobile and app CRO
• Checkout optimization UX/UI enhancements
• CRO for SEO and paid ads
• Advanced testing

Depending on the pricing model and the type of project, a CRO agency may charge from $2,000 to $30,000 per month.

Most businesses see initial conversion rate improvements within 4-6 weeks once testing and quick wins are implemented. Deeper, more sustained gains usually appear after 3-6 months as multiple A/B tests, UX changes, and optimization cycles compound.

Look for a CRO agency with proven case studies, data-driven methodology, and expertise in A/B testing, analytics, and UX/UI design.

Ensure they provide transparent reporting, industry experience, and a clear testing roadmap tailored to your goals. The best agencies also integrate seamlessly with your marketing stack and emphasize measurable ROI.

A CRO agency might not be the best fit if it displays the following warning signs:

• No proven case studies or vague claims of past success
• One-size-fits-all approach without tailoring to your business goals
• Overpromising quick wins without a clear testing roadmap
• Lack of transparency in reporting or unclear KPIs
• Little to no UX/UI expertise, focusing only on copy tweaks
• Ignoring data and relying solely on opinions or assumptions
• Poor integration skills with your analytics, CMS, or marketing tools

Before signing a contract with a CRO agency, ask them the following questions:

1. How many years of experience do you have in CRO?
2. Do your team members have relevant certifications like Google Analytics, HubSpot, and others?
3. How do you make clients stand out from the competition?
4. What is your approach to A/B testing?
5. What does your CRO audit process entail, and how long does it last?
6. How do we define project milestones? What happens if they are not met?
7. What metrics will you use to define the success of this CRO campaign?
8. What is the planned budget? Are there any additional costs we can expect?

Conversion rate optimization focuses specifically on turning existing traffic into leads or sales through testing, analytics, and funnel improvements. Digital marketing, on the other hand, drives traffic via channels like SEO, PPC, and social, while UX services improve overall usability and design.

CRO bridges both by using data to maximize conversions from the traffic and experiences those efforts create.

Top CRO agencies use A/B and multivariate testing tools like Optimizely, VWO, and AB Tasty, together with behavior analytics platforms such as Hotjar, FullStory, Mixpanel, and Heap to track user actions. They also rely on feedback tools for surveys and usability testing, plus onboarding optimization tools like Userpilot to refine customer journeys.

For experimentation, conversion rate optimization agencies rely on frameworks such as ICE, PIE, and PXL to prioritize tests, along with models like the Lift Framework and JTBD for structured hypothesis building.

Our goal is to provide accurate and useful information to both businesses and agencies, which is why we partnered with Mike Melen, co-founder of digital marketing agency SmartSites. He shared best practices for optimizing user journeys and reducing friction in the conversion process. 

As a young entrepreneur, Mike Melen sold his first company at 19 years old. He has since led SmartSites, which has garnered eight Inc. 5000 recognitions and more than 1,000 5-star reviews. Melen’s work in the marketing field has also received honorable mentions from Forbes, AdWeek, and Inc. Magazine.