Klaviyo is a marketing automation and customer relationship management (CRM) platform built for business-to-consumer (B2C) brands, best known as the system behind the personalized emails and text messages that follow an abandoned online shopping cart. The company, pronounced CLAY-vee-oh and listed on the New York Stock Exchange under the ticker KVYO, exists because online stores generate detailed purchase and browsing data that generic email tools historically could not read in real time. Klaviyo stores that data itself and triggers messages from it.

Since February 2025 the company has positioned the product as a B2C CRM, and since March 2026 as an autonomous one, bundling marketing, analytics, customer service, and artificial intelligence (AI) agents on a shared data layer. More than 205,000 brands used the platform as of June 30, 2026, among them Mattel, Glossier, TaylorMade, and Liquid Death, according to the company's second-quarter results. Revenue passed $1.2 billion in 2025, up 32 percent from $937 million a year earlier, according to the full-year report published on February 10, 2026.

How the platform works

Everything in Klaviyo hangs off two objects: the profile and the event. A profile represents one person - an email address, a phone number, consent status, and whatever attributes a brand attaches. An event is a timestamped action tied to that profile: Viewed Product, Started Checkout, Placed Order, Opened Email. Data arrives through more than 350 integrations, led by a Shopify connection the company says syncs store data in milliseconds, plus application programming interfaces (APIs) for custom sources. The research firm Sacra estimated the system processes more than 2 billion events per day across upwards of 7 billion profiles, according to its company profile.

Marketers then build segments, dynamic audience queries that update in real time - customers who spent above a threshold but have not purchased in 90 days, for example. Messages leave the platform in two forms. Campaigns are one-off sends, such as a product launch announcement. Flows are automations triggered by events or dates: the welcome series after a signup, the abandoned-cart reminder, the post-purchase review request, the win-back sequence. Channels span email, short message service (SMS) texts, WhatsApp, mobile push, and, since 2026, social messaging through a product called K:Social. A predictive layer estimates each profile's lifetime value, churn risk, and expected next order date.

On the operating side, the platform is typically run by in-house retention, lifecycle, or CRM teams, often supported by specialist email agencies; consumers only ever see the output. Since February 27, 2024, an AI layer branded Klaviyo AI has generated subject lines, segments, and send-time decisions. In 2026 that layer became agentic: Composer assembles entire campaigns and flows from a single prompt, while Customer Agent handles service conversations such as order tracking, returns, and subscription edits.

Pricing built on active profiles

Klaviyo charges by relationship rather than by volume. A free tier covers 250 active profiles, 500 monthly emails, and 150 SMS credits; paid email plans start at $20 per month and step up with every profile tier, with sending capped at ten times the profile count, according to independent pricing analyses. The model turned contentious on February 18, 2025, when billing shifted from the contacts a brand actually messaged to every contactable profile in the account, applied automatically to legacy customers, according to Klaviyo's help center. Plans now upgrade automatically when counts cross a threshold, contacts that are unsuppressed cannot be suppressed again for 90 days, and Klaviyo capped any single increase at 25 percent at rollout, according to an analysis by the email platform Audienceful.

From bootstrapped side project to public company

Andrew Bialecki and Ed Hallen, former colleagues at Applied Predictive Technologies, founded Klaviyo in Boston in 2012. They ran it without outside capital for three years; by the time Accomplice led a $1.5 million seed round in 2015, the business had passed $1 million in revenue and was profitable, according to Forbes. Summit Partners led a Series B round in 2019, and a $320 million round led by Sands Capital in May 2021 valued the company at $9.5 billion. Sources differ on when SMS launched: Sacra dates the product to 2019, built to counter fast-growing text specialists Attentive and Postscript, while a Summit Partners retrospective places the launch alongside the 2021 financing.

Shopify reshaped the trajectory in August 2022, investing $100 million and naming Klaviyo the recommended email partner for its Shopify Plus merchant tier. A first acquisition, developer tool Napkin.io, followed in November 2022. In 2023 the company added a customer data platform (CDP) product and reviews, then went public on September 20, 2023 at $30 per share, raising roughly $576 million; the stock gained 23 percent on debut, according to Forbes.

Reinvention accelerated after the initial public offering (IPO). Klaviyo AI arrived in February 2024. On February 20, 2025, the company announced Klaviyo B2C CRM, splitting the platform into Klaviyo Marketing, Klaviyo Analytics, and Klaviyo Service - including a shopper-facing Customer Hub - all running on the Klaviyo Data Platform (KDP). On December 9, 2025, former Workday co-chief executive Chano Fernandez was appointed co-CEO effective January 1, 2026, taking over go-to-market and operations while Bialecki concentrates on AI products. The word autonomous entered the branding on March 24, 2026, when Composer was introduced alongside more than 75 platform features.

Why Klaviyo matters for marketers

Owned channels have become the counterweight to rising paid media costs, and Klaviyo sits at the center of that shift for consumer brands. The company told investors that purchases attributed to its messages reached $2.3 billion in the United States during the 2025 Black Friday-Cyber Monday window, against an estimated $44.2 billion in total US online sales across those five days - roughly one dollar in twenty - according to an investor presentation reviewed by Investing.com.

The data asset increasingly matters beyond the inbox. On July 16, 2026, Contentsquare began syncing behavioral segments directly into Klaviyo, letting checkout-friction signals trigger recovery messages without manual exports. Klaviyo also joined Comcast's Universal Ads platform as one of its first Audience partners, extending brand-built segments into television campaigns; Eddie O'Brien, Klaviyo's senior vice president of global partnerships and alliances, framed the move around the belief that "customer-first growth starts with data." First-party CRM audiences, in short, are becoming currency across channels the platform never touched before.

Limitations, criticisms, and open disputes

The 2025 billing change remains the sharpest grievance. Brands carrying large dormant lists faced effective price rises without any sticker change, and on the August 5, 2026 earnings call management acknowledged that lapping the prior year's profile enforcement weighed on net revenue retention, which stood at 109 percent. Concentration is a second concern: more than 117,000 customers run Klaviyo with Shopify, according to the company's own Shopify App Store listing, and Shopify holds a stake of roughly 11 percent - a relationship that would cut deep if terms ever shifted.

The economics draw scrutiny too. Adjusted gross margin fell to 73.4 percent in the second quarter of 2026 from 76.4 percent a year earlier as SMS carrier fees grew faster than the wider business, and the company still reports losses under generally accepted accounting principles (GAAP), including a $31.8 million net loss for 2025. Shares dropped 11.55 percent after hours to $17.07 on the second-quarter report, according to Investing.com. Competitors press on capability gaps as well: a Wunderkind buyer's guide distributed on January 22, 2026 argued that email service providers (ESPs) including Klaviyo cannot see the up to 95 percent of website traffic that stays anonymous, while CDP.com has noted that the fullest data-platform features sit behind a separate paid add-on.

Klaviyo and adjacent terms

Mailchimp, owned by Intuit, is a general-purpose small-business email tool organized around audiences rather than event streams; Klaviyo's depth lies in commerce events. Attentive is an SMS-first enterprise platform, whereas Klaviyo bundles SMS and email onto a single profile and bill. Braze targets enterprise, mobile-app-first engagement such as push and in-app messaging and typically pairs with an external data layer. A standalone customer data platform such as Twilio Segment moves data between systems but sends nothing itself; Klaviyo's KDP is an embedded, partially gated equivalent rather than a neutral pipe.

Recent developments

Composer moved to public beta on June 30, 2026, and management said the agent passed 95,000 users in its first month while Customer Agent adoption rose 40 percent quarter over quarter. Second-quarter revenue of $370.6 million grew 26 percent year over year, and full-year 2026 guidance rose to between $1.526 billion and $1.534 billion, though third-quarter growth was guided down to 21.5 to 22.5 percent. On August 5, 2026, Klaviyo agreed to acquire the team and technology of Agency, an AI customer-success startup whose chief executive Elias Torres becomes chief product officer; operating income guidance was trimmed to absorb the deal. A Klaviyo app inside ChatGPT, announced with fourth-quarter 2025 results, extended the data into OpenAI's assistant. "2025 was a breakout year for Klaviyo," Bialecki said in February 2026. The decelerating quarterly growth curve will determine whether 2026 earns the same description.

Timeline

  • 2012: Andrew Bialecki and Ed Hallen found Klaviyo in Boston and bootstrap it for three years
  • 2015: Accomplice leads a $1.5 million seed round; the company is already profitable with more than $1 million in revenue
  • 2019: Summit Partners leads the Series B round; Sacra dates the SMS product launch to this year
  • May 2021: A $320 million round led by Sands Capital values Klaviyo at $9.5 billion
  • August 2022: Shopify invests $100 million and names Klaviyo the recommended email partner for Shopify Plus
  • November 2022: Klaviyo makes its first acquisition, developer tool Napkin.io
  • 2023: Klaviyo CDP and a reviews product launch
  • September 20, 2023: Initial public offering on the New York Stock Exchange at $30 per share, raising roughly $576 million
  • February 27, 2024: Klaviyo AI launches
  • February 18, 2025: Active-profile billing takes effect for all accounts, announced January 14, 2025
  • February 20, 2025: Klaviyo B2C CRM debuts, uniting Marketing, Analytics, and Service on the Klaviyo Data Platform
  • December 9, 2025: Chano Fernandez is appointed co-CEO, effective January 1, 2026
  • February 10, 2026: Full-year 2025 results show $1.2 billion in revenue, up 32 percent, and more than 193,000 customers
  • March 24, 2026: Composer is introduced and Klaviyo adopts autonomous B2C CRM positioning
  • June 30, 2026: Composer enters public beta alongside Customer Agent expansion
  • August 5, 2026: Second-quarter revenue reaches $370.6 million, up 26 percent, and the Agency acquisition is announced

Summary

Who: Klaviyo, founded by Andrew Bialecki and Ed Hallen and now co-led by Bialecki and Chano Fernandez, serves more than 205,000 consumer brands including Mattel, Glossier, TaylorMade, and Liquid Death, with Shopify as a strategic shareholder holding roughly 11 percent.

What: A B2C customer relationship management platform that unifies first-party profile and event data, then activates it through email, SMS, WhatsApp, mobile push, and social messaging, plus analytics, customer service tools, and AI agents such as Composer and Customer Agent, priced by active profile count.

When: Founded in 2012, public on the New York Stock Exchange since September 20, 2023, repositioned as a B2C CRM on February 20, 2025, and marketed as an autonomous B2C CRM since March 24, 2026.

Where: Headquartered in Boston with hubs in Dublin and Singapore, serving customers worldwide; revenue outside the Americas grew 35 percent year over year in the second quarter of 2026.

Why: Consumer brands need owned channels and first-party data activation as paid media costs climb and third-party identifiers erode; Klaviyo supplies both in one system, though its active-profile pricing, Shopify dependence, and margin pressure from SMS remain points of dispute.