Reliable free API for financial stock and crypto data

# Free API Services for Stock and Crypto Data ## TL;DR For crypto data: **CoinGecko** and **CoinMarketCap** offer the most generous free tiers with 10K monthly credits, covering 20K+ tokens with real-time prices, market caps, and basic tokenomics. For stock data: **Alpha Vantage** and **Finnhub** provide the best balance of reliability and free access, supporting NYSE/NASDAQ with historical data and fundamentals. Community feedback favors CoinGecko for data honesty and Alpha Vantage for ease of integration, though rate limits remain a common constraint across all free tiers. ## Cryptocurrency Data APIs | API Service | Free Tier Limits | Data Coverage | Key Strengths | Limitations | |-------------|-----------------|---------------|---------------|-------------| | **CoinGecko** | 10K calls/month, 30 calls/min | 23M+ tokens, 200+ networks, real-time prices (60s delay), market caps, volumes, tokenomics | 100% uptime past 60 days, trusted by Etherscan/MetaMask, comprehensive coverage | Personal use only, 1-year historical depth, 60-second data freshness | | **CoinMarketCap** | 10K calls/month, 30 req/min | 10K+ assets, 790+ exchanges, real-time prices, market caps, volumes | High adoption (1B+ calls/month), Binance ecosystem, financial-grade | No historical data, 1 asset/call limit, 11 endpoints only | | **CoinPaprika** | 20K calls/month | Top 2,000 assets, 1-year daily historical, hourly OHLCV, social data | 99.9% uptime, 1-day hourly data, social metrics (X/GitHub) | Non-commercial only, 10-minute updates, no circulating supply | | **Binance Public API** | IP-based (1200 weight/min) | Binance-listed pairs, real-time via REST/WebSocket | Exchange-grade uptime, no API key needed, high volume capacity | Binance pairs only, IP bans for abuse, weight-based limits | | **DEXScreener** | Open access (fair use) | DEX prices/volumes (Solana, Ethereum, etc.) | Real-time DEX data, commercial-friendly terms | DEX-only (no CEX), unspecified rate limits, limited historical | ### Community Sentiment on Crypto APIs **CoinGecko** receives strongest positive feedback for honest data presentation and reliable integration with AI tools, showing adequate capacity under load during project launches. Users prefer it over competitors for faster loading and data accuracy. **CoinMarketCap** faces criticism for volume calculation inaccuracies and delayed supply updates, though developers appreciate straightforward data retrieval for basic panels and dashboards. **Binance Public API** proves reliable for algorithmic trading but vulnerable to exchange-wide downtime during high volatility. Security practices (2FA, restricted permissions) essential due to scam risks. ## Stock Market Data APIs | API Service | Free Tier Limits | Data Coverage | Key Strengths | Limitations | |-------------|-----------------|---------------|---------------|-------------| | **Alpha Vantage** | 5 calls/min, 500 calls/day | NYSE, NASDAQ, global stocks/ETFs, forex, technical indicators, fundamentals | Near 100% uptime, easy integration, broad market coverage | Strict rate limits, delayed real-time data, premium needed for volume | | **Finnhub** | 60 calls/min | NYSE, NASDAQ, LSE, global stocks/ETFs/indices, forex, crypto, news, fundamentals | 99.99% uptime SLA, generous free tier, 1-year historical depth | Limited fundamentals depth, WebSocket paid-only | | **Polygon.io** | 5 calls/min | US stocks/ETFs, EOD/historical data (15-min delayed real-time) | 2ms response times, excellent performance for trading bots | US-only, 2-year historical limit, no full real-time | | **Financial Modeling Prep** | 250 calls/day | NYSE, NASDAQ, US stocks/ETFs, 5-year EOD historical, fundamentals | Strong fundamentals coverage, good uptime | US-centric, limited real-time, 300 calls/min cap | | **Tiingo** | 1K req/day, 50/hour, 500 symbols/month | NYSE, NASDAQ, global equities, EOD/intraday historical, crypto | High data quality/cleaning, global coverage | No fundamentals/news, personal use only | | **Twelve Data** | 800 credits/day | NYSE, NASDAQ, US stocks/forex/crypto, real-time/historical | 99.95% SLA, multi-asset support | Limited credits/symbols, global/WebSocket paid | | **Marketstack** | 100 req/month | 70+ global exchanges, EOD historical (1 year) | ~100% uptime, trusted by 30K+ users | Very low volume, no real-time/intraday | | **Yahoo Finance (yfinance)** | Unlimited (unofficial) | NYSE, NASDAQ, LSE, global exchanges, historical/real-time, fundamentals | No rate limits, comprehensive data | Unofficial/fragile, breaks with site changes, not production-ready | ### Community Sentiment on Stock APIs **Alpha Vantage** praised for clean integration with UI libraries and LLMs, enabling custom stock price tools and charts. However, criticized for data granularity issues, latency inconsistencies, and tight free tier limits causing intraday gaps—adequate for retail but insufficient for quantitative analysis. **Polygon.io** faces developer complaints about missing candles, latency variations, and inaccurate tick data impacting backtests. Recommended against for precision-dependent signal development due to unreliable data quality on free tier. **Yahoo Finance (yfinance)** widely used but inherently unstable as an unofficial scraping-based solution, subject to breaking changes and potential blacklisting. ## Key Recommendations ### For Crypto Data - **Best Overall**: CoinGecko for comprehensive coverage (23M+ tokens), proven uptime, and broad ecosystem trust - **High Volume Needs**: CoinPaprika (20K calls/month vs. 10K competitors) - **DEX Focus**: DEXScreener for real-time decentralized exchange data - **Trading Bots**: Binance Public API for exchange-grade reliability on listed pairs ### For Stock Data - **Best Overall**: Finnhub for generous rate limits (60 calls/min) and global coverage with 99.99% uptime - **Fundamentals**: Financial Modeling Prep for deep US stock fundamental data - **Speed Priority**: Polygon.io for 2ms responses (trading bots, real-time needs) - **Budget/Learning**: Alpha Vantage for ease of integration despite stricter limits ### Critical Considerations 1. **Commercial Use**: Most free tiers restrict commercial applications—verify licensing terms 2. **Rate Limits**: Plan architecture around limits (caching, batching, async calls) 3. **Data Freshness**: Free tiers typically impose 15-60 second delays or EOD-only access 4. **Historical Depth**: Limited to 1-2 years on free tiers; premium needed for deeper backtesting 5. **Reliability**: Production systems should consider paid tiers or multi-API fallback strategies 6. **Security**: For exchange APIs (Binance), implement 2FA and restricted permissions to prevent unauthorized access All data current as of January 6, 2026 UTC. Free tier specifications subject to change—verify current pricing pages before implementation.