Top Financial Data API: Guide & Comparison

IEX Cloud, once celebrated as a low-cost, developer-friendly alternative to institutional data providers, officially shut down on August 31, 2024. Launched with the mission of democratizing access to market data, it earned a loyal following among indie developers, fintech startups, and quants who valued its simple pricing and clean APIs. However, sustaining a standalone data business in a competitive and resource-intensive market proved challenging. The closure left many scrambling to migrate their applications to other providers such as Alpha Vantage, Intrinio, or Quandl. While its sun has set, IEX Cloud remains an important chapter in the story of financial data democratization—proof that accessibility matters, and that even small players can push an industry toward greater openness.

In this article, I will provide an in-depth survey of 8 stock market data API providers as alternatives to IEX Cloud. 

Alpha Vantage has established itself as the best overall stock API by striking the perfect balance between accessibility and depth. With real-time and historical data spanning stocks, ETFs, forex, crypto, and commodities, it empowers everyone from hobbyist traders to professional quants. The platform’s clear documentation, active open-source community, and generous free tier make it especially appealing for developers and startups looking to quickly integrate reliable financial data without breaking the bank. 

Alpha Vantage has also launched its official MCP server, allowing AI agents to query market data directly—removing friction for builders who want AI-driven research and trading workflows. Affordable, versatile, and future-ready, Alpha Vantage is the go-to stock API for anyone serious about building modern financial applications.

Quandl, now fully integrated into Nasdaq Data Link, remains one of the most recognizable names in financial and economic data. Originally known for democratizing access to alternative datasets, Quandl built its reputation on providing analysts, researchers, and developers with streamlined access to hard-to-find information, ranging from macroeconomic indicators to niche alternative data. Its simple API structure and robust documentation made it an early favorite for academics, data scientists, and fintech innovators who wanted to enrich models with more than just price and volume data. 

Under the Nasdaq Data Link brand, Quandl continues to deliver high-quality financial, economic, and alternative datasets, but with the added weight of Nasdaq’s infrastructure and credibility. The platform offers both free and premium data feeds, ensuring accessibility for individuals while still catering to institutional clients. For anyone building models that go beyond equities—whether incorporating fundamentals, economic signals, or specialized datasets—Quandl (Nasdaq Data Link) is still a trusted and comprehensive source.

QUODD is an enterprise-grade market data provider best known for delivering institutional-quality pricing and reference data across a wide spectrum of global asset classes. Its strength lies in offering real-time and delayed feeds for equities, options, mutual funds, ETFs, fixed income, and more—delivered through APIs, desktop applications, and data portals designed for financial professionals. QUODD has built a strong reputation in wealth management, brokerage, and advisory segments by providing reliable, entitlement-controlled data at scale, backed by responsive client support. 

The acquisition of Xignite in 2024 significantly expanded QUODD’s footprint in the developer and fintech ecosystem. By combining QUODD’s institutional data infrastructure with Xignite’s extensive catalog of over 500 APIs, the platform now serves both enterprise clients and tech-driven innovators. This positions QUODD as a hybrid powerhouse: capable of handling the demanding compliance and distribution needs of large institutions while also appealing to developers and fintech startups looking for flexible, API-first access to market data.

Polygon.io has quickly emerged as one of the most developer-friendly financial data platforms, specializing in real-time and historical market data delivered via clean, modern APIs. Focused primarily on U.S. markets, Polygon.io offers low-latency access to equities, options, forex, and crypto, making it especially popular with algorithmic traders, fintech startups, and quant researchers. Its straightforward REST and WebSocket APIs, coupled with tiered subscription plans, make it easy for developers to scale from side projects to production-grade trading systems without dealing with the complexity often found in legacy data providers. 

While it doesn’t yet match the global breadth of larger institutional players, Polygon.io shines in its niche: delivering high-quality, developer-first APIs for U.S. market data. For builders who want fast, scalable access to core markets without enterprise overhead, Polygon.io is one of the best choices available.

Intrinio has carved out a strong position in the financial data landscape by offering modular, easy-to-integrate packages that let users pay only for the data they actually need. Their catalog spans equities, options, ETFs, and fundamentals, with coverage ranging from real-time and delayed feeds to over 50 years of historical end-of-day data. This flexibility, paired with transparent tiered pricing (bronze, silver, and gold), makes Intrinio particularly attractive for fintech developers, quants, and financial app builders who want to balance cost with precision. Beyond market data, Intrinio also offers ESG datasets and alternative data, broadening its appeal to users looking for differentiated signals. 

MarketStack is a lightweight, developer-friendly API designed to make global stock market data accessible to a wide audience. With coverage spanning over 70 global exchanges and more than 170,000 tickers, it delivers both real-time and historical data in a clean RESTful format. Its appeal lies in its simplicity—developers can get started quickly with straightforward endpoints for end-of-day prices, intraday data, and ticker lookup, all backed by a transparent pricing structure that includes a generous free tier. This makes MarketStack an attractive option for individual traders, hobbyists, and small fintech teams who want a quick and affordable way to plug market data into their applications. Where MarketStack shines is in lowering the barrier to entry. 

While it doesn’t yet match the ultra-low latency or breadth of institutional-grade providers, it offers a solid balance of affordability and functionality. The platform is particularly well-suited for educational projects, portfolio trackers, and small-scale trading tools where ease of use and low cost are more important than enterprise-level guarantees. 

EOD Historical Data has built its reputation on delivering comprehensive, affordable access to end-of-day and historical market data across global exchanges. Covering over 70 stock exchanges worldwide with more than 150,000 tickers, the platform provides equities, ETFs, mutual funds, indices, and forex data in a simple RESTful API format. Alongside daily and intraday pricing, EOD also offers fundamental data, macroeconomic indicators, and bond information, making it a well-rounded resource for investors, developers, and financial researchers. Its straightforward pricing tiers and generous data depth make it particularly attractive for startups, independent traders, and academic use cases. 

What makes EOD Historical Data stand out is its balance of global breadth and affordability. While it doesn’t target ultra-low-latency or enterprise-level use cases like larger institutional providers, it excels at providing high-quality, structured datasets that are easy to integrate into trading systems, backtesting models, or educational projects. With coverage spanning decades of historical data and fundamental insights, EOD is ideal for those who value cost-effective access to international markets without sacrificing depth. 

QuoteMedia is a well-established provider of market data solutions, offering a broad suite of APIs, data feeds, and tools that serve brokerages, financial media outlets, and investor relations platforms. Their coverage spans equities, options, mutual funds, ETFs, indices, commodities, and fixed income, with both real-time and historical access. In addition to raw data, QuoteMedia delivers integrated news, charting tools, and financial content—making it a one-stop solution for platforms that need to embed professional-grade market information directly into their user interfaces. 

What sets QuoteMedia apart is its emphasis on turnkey integration. Beyond APIs, the company offers white-label and widget-based solutions that allow firms to quickly launch data-rich portals, dashboards, and apps without building everything from scratch. This makes it particularly attractive for broker-dealers, investor relations departments, and fintechs that need reliable market content in a polished, customer-facing format. While it may not match the cutting-edge developer focus of newer players, QuoteMedia continues to stand out in as a dependable, enterprise-ready option for embedded financial data.