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APIs Explained: How They Power Web & Crypto Apps

A practical guide to APIs: what they are, how they work, common types, security and evaluation steps, plus practical tips for integrating web and crypto APIs.
Token Metrics Team
5
MIN

APIs — short for Application Programming Interfaces — are the invisible wiring that connects software, data, and services. From mobile apps fetching weather to crypto platforms streaming on-chain data, APIs turn discrete systems into interoperable ecosystems. This guide explains what an API is, how it works, common types and protocols, practical evaluation criteria, and how AI-driven tools can help you research and integrate APIs safely and effectively.

What is an API? A practical definition

An API is a set of rules and conventions that lets one software program request services or data from another. Think of it as a contract: the provider exposes endpoints and documented inputs/outputs, and the consumer sends requests and receives structured responses. APIs abstract complexity, enforce consistency, and enable modular development.

At a high level, an API specifies:

  • Available operations (endpoints) and the expected parameters
  • Data formats for requests and responses (JSON, XML, etc.)
  • Authentication and authorization methods (API keys, OAuth)
  • Rate limits, error handling, and versioning policies

How APIs work: endpoints, methods and data flow

Most modern web APIs operate over HTTP. A consumer makes a request to a URL (endpoint) using an HTTP method such as GET, POST, PUT, or DELETE. The server processes the request and returns a response payload plus status codes that signal success or error.

Core concepts:

  • Endpoint: A URI representing a resource or action (e.g., /prices/bitcoin).
  • Request: Includes method, headers (authentication, content-type), query or body parameters.
  • Response: Status code (200, 404, 500) and structured data (commonly JSON).
  • Idempotency: Whether repeated requests have the same effect (important for retries).

Understanding these mechanics helps you design integrations, debug issues, and interpret API documentation efficiently.

Common API types and protocols

Not all APIs are built the same. Choosing the right style depends on use case, performance needs, and client ecosystem.

  • REST APIs: Resource-based, conventionally using HTTP verbs and stateless interactions. Popular due to simplicity and broad tooling support.
  • GraphQL: Query language that lets clients request exactly the fields they need. Useful when clients need flexible, efficient queries across related data.
  • WebSockets: Persistent, bidirectional socket connections ideal for real-time updates (chat, market feeds).
  • gRPC: High-performance RPC framework using Protocol Buffers—good for microservices and low-latency systems.
  • SOAP: Legacy, XML-based protocol with strict standards—still used in some enterprise environments.

Each approach has trade-offs: REST is simple but may require multiple round-trips, GraphQL reduces over-fetching but adds server complexity, and WebSockets enable streaming but require connection management.

Security, authentication, and operational governance

APIs often provide access to valuable data and functionality, so security and governance are paramount. Key considerations include:

  • Authentication: API keys, OAuth 2.0, JWTs. Choose methods that match risk and user flows.
  • Authorization: Enforce least privilege—limit which endpoints and operations each credential can access.
  • Rate limits and quotas: Protect infrastructure from overload and abusive usage.
  • Encryption & TLS: Always use HTTPS for data in transit; consider encryption at rest for sensitive payloads.
  • Auditing & monitoring: Log access patterns, errors, and anomalies for forensic and operational visibility.
  • Versioning: Maintain backward compatibility with explicit versioning strategies to avoid breaking consumers.

Operational SLAs, clear error codes, and robust documentation reduce integration friction and surface potential risks early.

How to evaluate and integrate an API: a practical checklist

When assessing a third-party API, use a structured framework:

  1. Documentation quality: Are endpoints, schemas, examples, and rate limits clearly described?
  2. Sandbox & test keys: Is there a sandbox for dry runs without impacting production data?
  3. Latency & throughput: Does the API meet your performance requirements under expected load?
  4. Reliability: Check status pages, historical uptime, and incident response practices.
  5. Cost model: Understand pricing tiers, overage fees, and whether free tiers suffice for initial development.
  6. Security posture: What authentication methods, encryption, and compliance certifications are provided?

For proofs of concept, use API testing tools (Postman, curl) and programmatic SDKs where available. Track metrics during integration and plan for retries, backoff strategies, and graceful degradation.

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FAQ: What is an API?

An API (Application Programming Interface) is a defined set of rules and endpoints that allows one software system to request data or services from another. It standardizes how data is exchanged and operations are invoked between systems.

FAQ: REST vs GraphQL — when to use each?

REST is simple and widely supported, ideal for straightforward resource-based access. GraphQL excels when clients need flexible, aggregated queries and want to reduce over-fetching. Choice depends on client needs and server complexity tolerance.

FAQ: How do APIs stay secure?

Security relies on strong authentication (API keys, OAuth), encryption (HTTPS/TLS), authorization controls, rate limiting, input validation, and monitoring. Regular audits and threat modeling help identify and mitigate risks.

FAQ: What are common API use cases?

APIs power mobile and web apps, payment processing, identity providers, data feeds (market, weather, maps), IoT device control, and integrations between enterprise systems or blockchain nodes.

FAQ: How do I test an API safely?

Use sandbox environments and test keys where available. Employ tools like Postman for exploratory testing, write automated integration tests, validate edge cases and error handling, and verify rate-limit behaviors under load.

Disclaimer

This article is for educational and informational purposes only. It explains technical concepts and evaluation frameworks but does not constitute professional, legal, or investment advice. Always perform your own due diligence when selecting or integrating APIs.

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Token Metrics Team

Recent Posts

Crypto Basics

How to Store Cryptocurrency Safely in 2025 | Hot vs Cold Wallets

Token Metrics Team
6 min
MIN

Cryptocurrency offers unmatched freedom, but with that freedom comes responsibility—especially when it comes to how to store cryptocurrency securely. Unlike traditional banking, crypto is self-custodied. If you lose access to your wallet, your funds are gone forever.

This guide explains everything you need to know about storing crypto in 2025, including:

  • Why crypto storage matters
  • Types of crypto wallets
  • Hot wallets vs. cold wallets
  • Tips for securing your assets
  • How platforms like Token Metrics can help protect your investment

đŸȘ™ Why Is Storing Cryptocurrency Important?

When you buy crypto—whether it’s Bitcoin, Ethereum, or a promising moonshot altcoin—you receive private keys that give you access to your funds. Anyone with that key can spend your coins.

That’s why safe storage is critical. Without it, your assets are vulnerable to:

  • Hacks and phishing scams
  • Lost devices or forgotten passwords
  • Exchange collapses or rug pulls

You are your own bank, and your security strategy is your vault.

🔐 What Is a Crypto Wallet?

A crypto wallet is a digital tool that stores your private and public keys. It lets you send, receive, and manage your crypto.

There are two main types:

  1. Hot wallets – connected to the internet
  2. Cold wallets – offline and physically secured

Let’s explore both.

🌐 Hot Wallets: Convenience Meets Risk

Hot wallets are always online, making them easy to use for trading, DeFi, or daily transactions.

Types of Hot Wallets:

  • Web wallets (e.g., MetaMask, Trust Wallet)
  • Mobile apps (e.g., Coinbase Wallet, Phantom)
  • Desktop wallets (e.g., Exodus, Electrum)

Pros:

  • Quick access to funds
  • Easy integration with DApps and exchanges
  • Great for beginners and active traders

Cons:

  • Higher risk of hacks, malware, and phishing
  • Device or browser compromise can expose keys

Best Practices for Hot Wallets:

  • Use 2FA (Two-Factor Authentication)
  • Never store large amounts
  • Double-check URLs to avoid fake websites
  • Avoid public Wi-Fi while transacting

🧊 Cold Wallets: Ultimate Security

Cold wallets are offline storage solutions, ideal for long-term investors or large holdings.

Types of Cold Wallets:

  • Hardware wallets (e.g., Ledger Nano X, Trezor)
  • Paper wallets (QR code + private key printed on paper)
  • Air-gapped devices (old smartphones with no internet access)

Pros:

  • Immune to online hacks
  • Best for HODLing and large sums
  • You own full control

Cons:

  • Less convenient for daily use
  • Loss or damage without backups = permanent loss

Best Practices for Cold Wallets:

  • Buy hardware wallets directly from the manufacturer
  • Backup your seed phrase on metal plates or offline storage
  • Keep backups in secure, separate locations

🔄 Custodial vs. Non-Custodial Wallets

🏩 Custodial Wallets

Managed by exchanges (e.g., Binance, Coinbase). You don’t own the private keys.

Pros:

  • Easy to use
  • Ideal for beginners

Cons:

  • Not your keys, not your crypto
  • Vulnerable to hacks or platform failures

🔓 Non-Custodial Wallets

You own the keys. Wallets like MetaMask, Trust Wallet, or hardware devices.

Pros:

  • Full control and ownership
  • Safer long-term storage

Cons:

  • Losing your seed phrase = permanent loss
  • Requires more responsibility

Tip: Token Metrics recommends non-custodial wallets for storing long-term holdings and moonshot tokens.

🔐 How Token Metrics Enhances Crypto Security

Token Metrics is an AI-powered crypto research and trading platform trusted by thousands of investors. While it doesn’t store your crypto directly, it helps you manage risk and store assets wisely by:

1. Identifying Safe Assets

Token Metrics gives you AI-generated grades for tokens—helping you avoid scams and invest in credible projects worth storing long-term.

2. Trading Tools with Wallet Integration

You can explore tokens, assess moonshots, and initiate trades directly from your connected Web3 wallet without leaving the platform.

3. Portfolio Tracking with Security

Token Metrics allows you to track wallets and portfolio performance without requiring access to your private keys.

4. Educational Guidance

Through webinars, blog content, and investor resources, Token Metrics educates users on how to safely store their crypto in hot and cold wallets.

🧠 Tips to Keep Your Crypto Safe in 2025

✅ Use Hardware Wallets for Large Amounts

Your long-term Bitcoin, Ethereum, and moonshot tokens should live on a hardware wallet, not on an exchange.

✅ Store Your Seed Phrase Offline

Do NOT keep your recovery phrase in Google Docs or your phone. Use metal seed phrase storage or write it down and lock it in a safe.

✅ Use Multiple Wallets

Diversify storage:

  • Hot wallet for daily use
  • Cold wallet for savings
  • Separate wallet for DeFi

✅ Avoid Suspicious Links and Apps

Phishing is the #1 crypto threat. Double-check URLs, don’t sign unknown transactions, and avoid shady browser extensions.

✅ Monitor Wallet Activity

Use platforms like Token Metrics Alerts or Etherscan to track your wallet and get notified of suspicious activity.

đŸȘ™ How to Store Different Types of Crypto

‍

🧭 Final Thoughts

Storing cryptocurrency securely is just as important as choosing the right tokens to invest in. Whether you’re a day trader, long-term investor, or moonshot hunter, knowing when and where to store your crypto is key to protecting your wealth.

In 2025, the best strategy combines:

  • Cold wallets for large, long-term holdings
  • Hot wallets for convenience and trading
  • Non-custodial options to retain full control
  • AI tools like Token Metrics to identify trustworthy assets and avoid scams

When you store your crypto properly, you don’t just protect your assets—you gain peace of mind.

Token Metrics API

How to Build Crypto Trading Dashboard Using the Token Metrics Crypto Data API on Dune

Token Metrics Team
8 min
MIN

In today’s fast-paced crypto world, real-time data isn’t a luxury—it’s a necessity. For traders, analysts, and developers, being able to access live, actionable insights can mean the difference between profit and loss. That’s why the integration of the Token Metrics Crypto Data API with Dune is a game-changer for anyone seeking to create live dashboards backed by intelligent trading data.

In this post, we’ll walk through how to use this top crypto API to build dynamic dashboards on Dune. Whether you’re tracking bullish signals, backtesting trading strategies, or identifying top-performing tokens, this integration makes it possible—without any paid license.

Let’s dive into how you can use the best free crypto API available today to transform your trading.

What Is the Token Metrics Crypto Data API?

The Token Metrics Crypto Data API is a developer-focused gateway to powerful, AI-driven crypto data. It’s one of the top crypto APIs in 2025, giving you access to:

  • Real-time and historical trading signals
  • Proprietary trader and investor grades
  • Alpha metrics comparing trading vs. holding performance
  • Bullish and bearish token flags

This API is used by both professional quant traders and beginners seeking to automate insights. And the best part? Token Metrics provides free crypto API access to selected datasets, allowing you to create powerful dashboards without spending a dime.

Why Dune + Token Metrics API = Power Tools for Traders

Dune is a blockchain analytics platform that allows you to write SQL queries and create dashboards using on-chain and off-chain data. Now that Token Metrics datasets are available on Dune, you can combine the best of both worlds:

  • Free access to high-signal proprietary metrics
  • Real-time data visualizations via Dune’s drag-and-drop dashboard builder
  • Actionable insights based on AI-driven trading intelligence

This integration unlocks a whole new level of transparency and utility for crypto analysts, portfolio managers, and DeFi enthusiasts.

Getting Started: Accessing Token Metrics Data on Dune

To begin, create a free Dune account. Once logged in, navigate to the Token Metrics datasets. These are publicly accessible and updated regularly. You’ll find tables for:

  • trading_signals
  • trader_grades
  • investors_grades
  • tokens

Start a new SQL query and choose the dataset you want to explore. Here’s what you’ll find in the trading signals table:

‍

‍

Step-by-Step: Creating an Actionable Dashboard with Token Metrics Data

1. Query the Trading Signal Returns

Write a SQL query to calculate the average return of trading vs. holding strategies. For example:

This gives you the alpha—how much better the Token Metrics strategy performs compared to just HODLing.

In one real example, the average signal return across all tokens was 1630%, while holding returned just 400%. That’s a 12X improvement powered by this top crypto API.

2. Identify Top-Performing Tokens

Now let’s list tokens with the highest average alpha:

Tokens like BTC, ETH, BNB, and even newer ones like Virtuals stand out due to exceptional alpha performance.

3. Visualize Trader Grades vs. Alpha

The trader grade is a proprietary score from Token Metrics that predicts how favorable a token is for short-term traders.

Use a scatter plot to correlate trader grades with average alpha:

  • X-axis: Trader Grade
  • Y-axis: Average Alpha
  • Group by: Token Symbol

This helps you visually determine which tokens score high and offer exceptional returns—an essential tool for making actionable trading decisions.

4. Track the Latest Bullish Signals

Want to know which tokens are bullish right now? Here’s a query to find the most recent tokens flagged as bullish:

For example, on July 4th, tokens like BNB, XRP, and BTC were among the most recent bullish signals—perfect for immediate trade setups.

5. Build and Share Your Dashboard

Once you’ve run your queries:

  • Click “Add Visualization” in Dune
  • Choose from chart types (bar, scatter, progress bar, etc.)
  • Customize colors and filters
  • Combine multiple charts into a single dashboard

Your final product will be a real-time dashboard powered by the best crypto API, delivering insights that you—and your team—can act on instantly.

Why Token Metrics Is the Best Free Crypto API for Traders

Here’s why Token Metrics stands out among other APIs:

✅ AI-Driven Signals

Most APIs deliver raw data. Token Metrics provides curated signals, generated from machine learning models trained on market cycles, indicators, and price action.

✅ Proprietary Metrics

Access unique indicators like trader grade and investor grade, unavailable anywhere else.

✅ Real Historical Alpha

Use the API to backtest strategies. In the example shown, the AI strategy outperformed the market by over 1000X for some tokens.

✅ Seamless Integration

Whether you're using Dune, Zapier, OpenAI, or Eliza OS, Token Metrics is easy to integrate and query—making it the top crypto API for developers and analysts alike.

Final Thoughts

The combination of Token Metrics’ intelligent data and Dune’s visualization tools puts immense power in your hands. Whether you’re tracking market trends, building bots, or guiding portfolio decisions, this integration gives you everything you need to trade smarter.

With free access to real-time trading signals, alpha comparisons, and powerful visualizations, Token Metrics proves why it's the best crypto API for today’s data-driven investor.

Ready to try it out?
👉 Explore the Free Crypto API
👉 Start Building on Dune

Crypto Basics

What Is an ETF Stock? A Beginner’s Guide to Exchange-Traded Funds in 2025

Token Metrics Team
8 min
MIN

In today’s fast-moving financial markets, Exchange-Traded Funds, or ETF stocks, have emerged as one of the most popular investment vehicles for beginners and professionals alike. But what exactly is an ETF stock, how does it work, and why is it considered a smart way to invest?

This guide will walk you through everything you need to know about ETF stocks in 2025—including how they work, their benefits and risks, and how AI platforms like Token Metrics are changing the way people research and trade ETFs in both traditional and crypto markets.

📌 What Is an ETF Stock?

An ETF stock refers to a share of an Exchange-Traded Fund—a type of investment fund that trades on stock exchanges, much like individual company stocks. Each ETF holds a basket of underlying assets such as:

  • Stocks (e.g., S&P 500 companies)
  • Bonds
  • Commodities (like gold or oil)
  • Currencies
  • Cryptocurrencies (Bitcoin, Ethereum, etc.)

When you buy an ETF stock, you’re buying a fractional share of the entire portfolio of assets held by that ETF.

🔍 How Does an ETF Stock Work?

ETF stocks work like this:

  1. Creation: An asset management company (like BlackRock, Vanguard, or Fidelity) creates an ETF that tracks a specific index, sector, or asset type.
  2. Listing: The ETF is listed on a stock exchange such as the NYSE or Nasdaq.
  3. Trading: Investors can buy and sell ETF shares throughout the trading day, just like they would a stock like Apple or Tesla.
  4. Price Movement: The price of an ETF stock fluctuates during the day based on the Net Asset Value (NAV) of its holdings and supply-demand dynamics in the market.

This model provides a liquid, transparent, and low-cost way for investors to gain diversified exposure to entire markets or sectors.

📊 Example of an ETF Stock

A good example is the SPDR S&P 500 ETF Trust (SPY), which tracks the performance of the S&P 500 index. When you buy a share of SPY, you gain exposure to 500 of the largest U.S. companies—without needing to buy each stock individually.

✅ Benefits of ETF Stocks

ETF stocks offer numerous advantages for investors in 2025:

1. Diversification

Instead of buying individual assets, ETF stocks offer instant diversification by holding dozens or hundreds of securities in a single share.

2. Liquidity

ETFs are traded on exchanges, making them highly liquid. You can buy or sell them at market prices during normal trading hours.

3. Lower Costs

ETFs typically have low expense ratios (as low as 0.03%), especially compared to mutual funds or actively managed portfolios.

4. Transparency

Most ETFs disclose their holdings daily, giving investors a clear view into what they’re buying.

5. Flexibility

You can use ETFs for long-term investing, short-term trading, hedging, or generating income through dividends.

⚠ Risks of ETF Stocks

Despite their many benefits, ETF stocks do come with some risks:

1. Market Risk

ETF stocks are still subject to market volatility. If the underlying assets decline in value, so will the ETF.

2. Tracking Error

Some ETFs may not perfectly replicate the performance of their index due to fees, slippage, or illiquid assets.

3. Overexposure

Because ETFs make it easy to invest, some investors may unknowingly become overexposed to a particular sector or strategy.

4. Liquidity Risk

Not all ETFs are created equal. Low-volume ETFs may have wider bid-ask spreads, increasing trading costs.

đŸȘ™ Crypto ETFs: The New Frontier

In 2025, crypto ETF stocks have become a hot trend. These funds allow investors to gain exposure to digital assets without managing private keys, wallets, or blockchain protocols.

Types of crypto ETFs include:

  • Spot ETFs: Hold actual crypto assets (e.g., Bitcoin, Ethereum).
  • Futures ETFs: Track the price of crypto futures contracts.

Popular examples in 2025 include:

  • IBIT (BlackRock Bitcoin ETF)
  • FBTC (Fidelity Bitcoin ETF)
  • ETHX (Ethereum Spot ETF)

Crypto ETFs have opened the door for institutional and traditional investors to gain exposure to the crypto market in a regulated and simplified manner.

đŸ€– How Token Metrics Helps You Trade ETF Stocks Smarter

Whether you're interested in traditional ETF stocks or crypto ETFs, Token Metrics provides the AI-powered insights you need to make better investment decisions.

🔎 1. AI-Powered Ratings

Token Metrics assigns each token or ETF a Trader Grade and Investor Grade based on price trends, volume, volatility, and technical strength—making it easy to spot outperformers.

📈 2. Bullish and Bearish Signals

AI-driven signals show when it’s time to buy or sell based on real-time metrics like ETF inflows, exchange balances, and market sentiment.

📊 3. Price Forecasts

Get access to predictive models that estimate where Bitcoin, Ethereum, and major crypto ETFs are headed—based on 80+ factors.

🔔 4. Smart Alerts

Set custom alerts for ETF stock signals, price movements, or grade changes so you never miss an opportunity.

By combining ETF investing with Token Metrics’ AI analytics, you gain an informational edge in markets that move faster than ever.

📈 Popular ETF Stocks in 2025

Here’s a list of top-performing ETF stocks across traditional and crypto sectors:

🧠 Final Thoughts

ETF stocks are a powerful investment tool in 2025, offering instant diversification, low fees, and easy access to traditional and crypto markets. Whether you're looking to build a retirement portfolio or ride the next Bitcoin rally, ETF stocks make it easier than ever to invest with confidence.

And with platforms like Token Metrics, you don’t need to guess your way through ETF trading. Use AI-driven insights, price predictions, and real-time data to get ahead of the curve—no matter what markets you trade.

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