Investors choosing between Duolingo (DUOL +4.10%) and Zeta Global (ZETA 0.25%) must weigh high-growth education technology against AI-powered marketing solutions. Both companies are navigating a rapidly evolving software landscape in 2026.
Duolingo uses gamification to maintain user engagement in the language learning market, while Zeta Global focuses on enterprise-level data analytics for digital marketing. They represent two different paths within the software sector, offering investors distinct ways to gain exposure to consumer-facing and business-to-business technology trends.
Duolingo provides language education through its flagship mobile app, which uses gamification to keep users returning. The company generates most of its revenue through subscriptions and advertising on its platform. Customer concentration like this adds a layer of risk to the business, as Apple and Alphabet together accounted for roughly 82% of total revenue in 2025.
In FY 2025, revenue reached $1 billion, which represents a growth rate of approximately 38.7% compared to the prior year. The company also reported net income of nearly $414.1 million for the same period. This resulted in a net margin of close to 39.9%, which helps investors assess how efficiently a company converts sales into profit.
As of its December 2025 balance sheet, the debt-to-equity ratio is roughly 0.1x, which measures total debt against shareholder equity. The current ratio is approximately 2.6x, indicating the company has sufficient assets to cover its short-term debts. Free cash flow for the year was roughly $369.7 million, though stock-based compensation represented roughly 35.4% of operating cash flow, which inflates reported cash generation since SBC is a non-cash expense added back in the cash flow statement.
Zeta Global provides an AI-powered marketing cloud that helps large enterprises acquire and retain customers through digital channels. The company recently entered a strategic partnership with Palantir Technologies to enhance its infrastructure for enterprise artificial intelligence. Since the top 10 customers account for more than one-third of total revenue, customer concentration like this adds a layer of risk to the business.
For FY 2025, the company reported revenue of close to $1.3 billion, representing growth of approximately 29.7% year over year. Despite this growth, the business reported a net loss of roughly $31.5 million. This resulted in a net margin of about -2.4%, showing that the company has not yet reached full-year profitability on a net basis.
On its December 2025 balance sheet, the debt-to-equity ratio was roughly 0.2x. The company maintains a current ratio of approximately 1.6x, providing a healthy cushion for short-term liabilities. Free cash flow was nearly $185.1 million, but stock-based compensation represented roughly 89.4% of operating cash flow, which inflates reported cash generation since SBC is a non-cash expense added back in the cash flow statement for tech stocks like this.
Duolingo faces significant revenue concentration risks because it is highly dependent on the app stores run by Apple and Alphabet. The company also competes in a crowded online learning market where new generative artificial intelligence products could disrupt its pricing power. Additionally, as of April 2026, the company is under investigation by law firms concerning potential federal securities law violations.
Zeta Global is heavily reliant on a small number of large clients, making the loss of any single major relationship a significant threat to financial results. The business must also navigate evolving data privacy laws like GDPR that could limit its ability to collect consumer data. Furthermore, integrating acquisitions and adapting to emerging AI-specific regulations pose ongoing challenges to its operational efficiency.
Zeta Global trades at a significantly lower multiple than Duolingo, suggesting a more conservative valuation for the AI marketing company relative to future earnings estimates.
Sector benchmark uses the SPDR XLK sector ETF. Valuation metrics sourced from Financial Modeling Prep (FMP) and may differ from other data providers.
Duolingo and Zeta offer very different products, but they appear to be at the same point in their growth journeys. Both sport market caps around $5 billion, both are applying artificial intelligence to power their businesses, and both face customer concentration risks. Duolingo shines in terms of its profitability, but Zeta’s product may make it the more compelling pick in this match-up.
Digital marketing is a big business, and if Zeta’s AI-powered product can differentiate itself in a crowded market, it could prove to be a runaway winner. Its partnership with tech giant Palantir is certainly a step in the right direction. Duolingo was a breakout star and offers a unique product, but online language learning may have more limited adoption, especially as more users become comfortable conversing with AI assistants.
Investing in tech stocks, particularly those that are deep in growth mode, can pay off handsomely for investors, but conservative investors are best served keeping these kinds of investments to smaller allocations within their portfolios, as the soaring highs can be quickly replaced by devastating lows.
Sarah Sidlow has positions in Alphabet and Apple. The Motley Fool has positions in and recommends Alphabet, Apple, Duolingo, and Palantir Technologies. The Motley Fool has a disclosure policy.
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Duolingo posts robust profits and growth, while Zeta Global leverages AI for enterprise marketing, but each faces distinct risks and valuation profiles.
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