Companies Using Clerk

With over a decade of experience in web crawling and technographic data analysis, I've examined Clerk's adoption footprint across our dataset of 50M+ crawled domains. This analysis draws on 557 enriched companies matched from 801 active Clerk deployments, as of our March 2026 crawl. Clerk, founded in March 2019 by brothers Colin and Braden Sidoti (per TechCrunch), has raised $134M in total funding across 7 rounds, including a $50M Series C led by Menlo Ventures and Anthropic's Anthology Fund in October 2025 (per clerk.com).

1. Growth trajectory

Our detection data shows Clerk growing from 284 active domains in January 2021 to a peak of 999 in April 2025, a 3.5x increase over four years. The growth curve has been steady: roughly 100-150 net new active domains added per year from 2021 through 2024. But web detection tells only part of the story. Clerk's own Series C announcement states the platform manages over 200 million users for over 15,000 applications (per clerk.com/blog/series-c). Ramp's transaction data ranked Clerk the #4 fastest-growing software vendor by customer count in December 2025 (per ramp.com), with an 18% adoption rate among identity provider buyers as of March 2026, up 5 percentage points year-over-year (per ramp.com/vendors/clerk).

"Clerk's growth to nearly 1,000 detected domains may look modest next to Auth0's 6,500+, but Ramp's #4 vendor ranking and Clerk's own 200M-user disclosure reveal a platform whose real footprint extends far beyond what web detection captures." - Mehmet Suleyman, Founder at TechnologyChecker.io

Sales Signal: Clerk is a growing addressable market with momentum confirmed by both detection data and third-party transaction data. Sales teams should target companies in the evaluation phase, particularly those comparing Clerk to Auth0 or Firebase Authentication. Ramp's data shows 21% of new category entrants chose Clerk, making it the #3 platform for first-time identity provider buyers.

2. Customer profile

The typical Clerk customer in our detection data is a micro-business with 1-10 employees (61.1%), founded between 2010-2019 (37.1%), operating in retail or e-commerce. Adding the 11-50 range brings the small-business concentration to 85%. This aligns with Ramp's data showing Clerk's highest adoption among micro-SMB companies at 29% (per ramp.com/vendors/clerk). Enterprise adoption (1,000+ employees) accounts for just 1.2% in our detection data, though notable exceptions exist: Klaviyo (public company, 1,000+ employees), Trustpilot, and Bufab Group all appear. Clerk's case study featuring Trading Experts, a financial education platform, confirms the developer-founder profile (per clerk.com/blog/trading-experts). Menlo Ventures noted that over 95% of Clerk's customers use all three core components (SignIn, SignUp, UserProfile), per their Series C investment perspective.

Sales Signal: Clerk's customer base is overwhelmingly small businesses and startups. Tools that serve these segments (hosting, payments, CRM for SMBs) can cross-sell effectively. The 95% component adoption rate signals deep product integration, not trial usage, which means churn risk is lower than typical SaaS platforms.

3. Industry and geographic concentration

The geographic distribution is striking: Denmark leads with 24.3% of all detected deployments, followed by Italy (19.8%) and the United Kingdom (13.1%). The United States, where Clerk is headquartered in San Francisco, accounts for just 2.3%. This European concentration, combined with Retail dominating at 24.3% of the industry mix, points to a strong e-commerce storefront use case among European retailers. Fashion brands (6.45%), sporting goods companies (3.01%), and wellness businesses (3.66%) round out the top verticals. No single industry exceeds 25%, but retail-adjacent verticals collectively account for over 37%.

Sales Signal: The Nordic and Southern European markets represent Clerk's current strongholds in our detection data. E-commerce service providers, Magento agencies, and European digital commerce consultancies are natural partners. The low US penetration in detection data contrasts with Ramp's US-focused transaction data showing strong adoption, suggesting Clerk's US footprint skews toward SaaS applications (which our crawler sees differently than e-commerce storefronts).

4. Migration patterns

Migration data, based on our 556 enriched companies, reveals one dominant corridor: Azure Active Directory. Clerk gained 206 companies from Azure AD and lost 134 to it, producing a 1.5:1 net gain ratio. All other competitors show negligible migration (1-3 companies each for Auth0, Okta, and Amazon Cognito). The Azure AD corridor dominates because both technologies serve European enterprise and retail environments where companies often transition from enterprise SSO to customer-facing auth solutions.

"The 1.5:1 gain ratio from Azure AD is encouraging for Clerk, but it's the only migration corridor with volume. The near-zero movement between Clerk and developer-focused competitors like Auth0 tells us these platforms serve genuinely different audiences." - Mehmet Suleyman, Founder at TechnologyChecker.io

Sales Signal: Companies leaving Azure AD for Clerk represent a specific migration pattern: moving from enterprise SSO to a lighter-weight, developer-friendly solution for customer-facing applications. Migration consultants and identity management specialists can position themselves as bridge providers. The 91 companies that left Azure AD for Clerk in the last year alone represent warm leads.

5. Technology ecosystem

The tech stack data from 556 enriched companies reveals an e-commerce-heavy ecosystem. Magento is the most common co-occurring platform at 27.2%, with Magento 2 at 22.8%. PrestaShop and Shopify POS each appear on 7% of Clerk sites. On the analytics side, Google Analytics runs on 94.2% of Clerk sites, with Hotjar (29.1%) and Microsoft Clarity (23.2%) showing strong UX analytics adoption. The JavaScript framework mix includes RequireJS (22.3%), Alpine.js (7.0%), and AngularJS (6.3%), reflecting both legacy and modern frontend stacks. Clerk itself officially supports Next.js, React, Remix, Expo, and Astro with dedicated SDKs (per clerk.com).

Sales Signal: Magento agencies and e-commerce platform consultancies are the most natural channel partners for reaching Clerk's existing detected base. The high Hotjar and Clarity adoption (29% and 23% respectively) suggests these companies invest in user experience optimization. Clerk's Agent Toolkit, launched in March 2025, integrates with Vercel's AI SDK and LangChain, opening a new prospecting angle for AI-native companies.

6. Key takeaways

1. Clerk has reached ~1,000 detected domains and claims 200M+ users across 15,000+ apps. Web detection captures a fraction of its actual footprint, which is heavily SaaS/API-based.

2. Ramp ranked Clerk #4 fastest-growing vendor (Dec 2025) and #3 for new adopter share (Mar 2026) among identity providers, confirming strong commercial traction.

3. The detected customer base is 85% small businesses (under 50 employees), concentrated in European retail and e-commerce.

4. Denmark (24.3%) and Italy (19.8%) account for nearly half of detected deployments, an unusual geographic distribution for a US-based auth platform.

5. Total funding of $134M across 7 rounds, with investors including Menlo Ventures, Anthropic, CRV, Stripe, and Madrona, signals sustained confidence in Clerk's developer-first approach.

7. Sales applications

Prospecting template: "Hi [Name], I noticed [Company] is using Clerk for authentication on [domain]. We work with [X] companies that rely on Clerk-powered storefronts and help them [value prop]. Based on TechnologyChecker.io data, [Company]'s profile matches our best customers: [industry] company, [size] employees, based in [country]."

Targeting strategy: Filter on TechnologyChecker.io for Clerk customers with 11-50 employees in Retail or Retail Apparel, founded 2010-2019, based in Denmark, Italy, or the UK. This captures the core ICP. Cross-reference with Magento detection for double-qualified leads.

Competitive angle: Companies that recently dropped Azure AD (91 in the last year) may be consolidating their identity stack. Clerk's free tier now covers 50,000 monthly retained users (expanded from 10,000 in 2026, per supertokens.com), lowering the barrier for switchers. These are active evaluators receptive to complementary tooling.

For the full dataset of 801 detected Clerk deployments and 557 enriched company profiles, explore the company list and filters on TechnologyChecker.io.