Top 12 Crypto APIs for Affiliates and Developers in 2025
Key Takeaways
APIs are the backbone of Web3 development
They connect apps to blockchains, wallets, smart contracts, and data — removing the need to build from scratch.Custodial vs Non-Custodial APIs impact control and compliance
Non-custodial APIs (like ChangeNOW) let users manage their own funds — ideal for DeFi. Custodial APIs offer easier integration but require user trust.Leading providers offer specialized features
From real-time data (QuickNode, Moralis) to enhanced RPC (Alchemy) and decentralized indexing (The Graph), each API serves a unique purpose.Scalability, pricing, and flexibility differ widely
Pick APIs based on your app’s needs, expected volume, and how much control you want over data and infrastructure.
Introduction
If Web3 is a new digital world, then crypto APIs are the bridges, tunnels, and highways that connect everything. Without APIs, you’re stuck trying to swim across an ocean with a backpack full of bricks. Good luck…
In simple terms, an API (Application Programming Interface) lets two software systems talk to each other. You request something; the API delivers it – fast and neat. In Web3, APIs connect your app to blockchains, wallets, smart contracts, price feeds, NFTs, and a hundred other things that would take years to build from scratch.
But here’s the thing – not all APIs are built the same.
Before jumping into the list, you should know one major difference between APIs: custodial vs non-custodial.
What are the Main Types of Web3 APIs?
Depending on your product, user expectations, and legal considerations, the type of API you choose will impact everything from technical design to user trust.
Non-Custodial APIs let users stay in control of their assets (not you). You integrate the tool, but users manage their own keys and funds – giving them freedom and ownership. ChangeNOW, for example, offers a non-custodial API. These are better for building DeFi apps or non-custodial wallets.
Custodial APIs, on the other hand, put asset control in the hands of the provider. These are often easier to integrate and come with fewer on-chain headaches – ideal for centralized exchanges, fintech apps, or complex trading platforms.
With that out of the way, let’s check out the top 10 API solutions in web3. Ready? Let’s go!
ChangeNOW API – Non-Custodial Instant Swaps
Overview
ChangeNOW is a non-custodial swap aggregator that connects your users directly to pooled liquidity, without ever touching their private keys. It supports over 1225+ cryptos and thousands of trading pairs, in addition to a substantial range of fiat currencies traders can use (70+), allowing it to meet the needs of a diverse range of traders.
Swaps typically finalize in under 5 minutes, backed by a 99.99 % uptime SLA to keep your service reliable.
You can pick fixed-rate swaps (lock in your price up front) or floating-rate swaps (optimize slippage dynamically), and ChangeNOW’s backend automatically handles stuck deposits, wrong-network errors, and other edge cases.
Since ChangeNOW never holds user funds, each transaction uses a unique deposit address – your users retain full custody throughout the process, reducing risk and minimizing liability.
Learn more about ChangeNOW's API here
Drawbacks
While ChangeNOW shines in speed and non-custody, it enforces minimum swap amounts – typically between $1.70 and $20, depending on the asset – so micro-transactions aren’t always feasible (not meant for scalping).
Late deposits can trigger updated network fees, which may slightly alter the final amount received.
Infura – Hosted Ethereum & IPFS Access
Overview
Running your own Ethereum node can be a full-time job: syncing from genesis, handling chain reorganizations, and scaling RPC endpoints. Infura removes that overhead by offering fully managed JSON‑RPC and WebSocket endpoints for Ethereum mainnet, popular testnets, all major layer‑2 rollups, and IPFS. You simply grab an API key, configure your HTTP or WebSocket client, and you’re connected within seconds.
Key Infura features include archive node access, allowing you to query account balances or contract states at any historic block height, which is critical for accurate audits, on‑chain forensic analysis, or NFT provenance tools.
Their Gas API provides real‑time fee suggestions across networks, integrating EIP‑1559 parameters and mempool congestion data so your transactions cost exactly what they should – no guessing, no wasted ETH.
Drawbacks
Infura’s convenience comes with potential centralization risk: relying on a single provider, even with distributed nodes, can create a point of failure outside your control.
High-volume applications may need to upgrade to premium plans to avoid rate limits, which can increase costs.
If your project requires highly customized node configurations or private networks, Infura’s standardized setup might not offer the flexibility you need.
Alchemy – Enhanced RPC with Developer Toolkit
Overview
Alchemy started as an RPC provider but quickly evolved into a full developer platform. Beyond standard JSON‑RPC calls, they offer enhanced APIs that package high‑level functionality into single endpoints.
Need to fetch an NFT’s metadata, owner, and transfer history? Alchemy’s NFT API returns all three in one shot. Want token balances with price and transfer data? Their Token API has you covered.
On the debugging side, Alchemy Build is a suite of tools designed to shave weeks off your troubleshooting: the Mempool Visualizer shows your pending transactions as they propagate through the network; the Debug Toolkit replays historical calls against a local fork of the chain; Composer and Explorer provide no‑code interfaces for querying chain state or constructing transactions.
For gas optimization, Alchemy’s Gas Manager dynamically suggests fees and even sponsors gas for end users under an account abstraction model (ERC‑4337 Smart Wallets).
With generous free tiers, built‑in alerts, and enterprise SLAs, Alchemy helps teams from small startups to blue‑chip protocols ship more features with fewer frantic calls to the node ops team.
Drawbacks
Alchemy’s powerful features can come at a premium. As your call volumes grow, advanced Build tools and large-scale usage may significantly raise your monthly bill.
Teams also face a learning curve: leveraging Alchemy’s specialized dashboards and APIs requires time to master, and deep integration can make switching to another provider more complex down the line.
QuickNode – High‑Performance Multi‑Chain RPC & Add‑Ons
Overview
Your dApp might start on Ethereum, but soon you’ll need Polygon, Arbitrum, BSC, or Solana. QuickNode’s claim to fame is lightning‑fast RPC across 67 chains and 110+ networks, all auto‑scaled to handle billions of calls per month. Average response times hover below 100 ms, even under heavy load.
QuickNode’s core service covers all standard RPC methods, but where they shine is in their add‑on suite.
Streams let you subscribe to block events, log filters, or balance changes via webhooks or WebSockets, with automated reorg detection.
Functions provide serverless compute – write JavaScript that triggers on-chain events, performs off‑chain logic, then writes back on‑chain, all without managing servers.
Their Rollups-as-a-Service (RaaS) offering lets teams deploy custom Layer‑2 chains, complete with RPC endpoints, block explorers, and bridges, in a fraction of the usual time. IPFS pinning, a simple key‑value store, and usage analytics round out a toolkit built for projects that need both raw speed and turnkey features without DevOps overhead.
Drawbacks
While QuickNode’s add-ons unlock advanced use cases, they can also lock you into its ecosystem, especially if you adopt its Rollups-as-a-Service or serverless functions extensively.
The modular pricing model may complicate budget forecasting, as each feature carries its own cost.
Coverage for newly launched or niche chains can lag, limiting support in some emerging ecosystems initially.
Moralis – Indexed Cross‑Chain Data
Overview
Raw RPC is powerful but messy. Moralis tackles that by indexing blockchain data across EVM and non‑EVM networks (Solana, Aptos, Avalanche, and more) into unified REST and WebSocket endpoints.
Their Wallet API returns a user’s native token balance, ERC‑20 holdings, NFTs, historical transactions, and even computed portfolio P&L in one payload.
For real‑time updates, Moralis Streams push parsed contract events and transfer logs to your webhooks or WebSocket clients – no need to maintain subscription filters or write hex parsers.
The NFT API surfaces metadata, rarity rankings, and spam filtering tags, simplifying marketplace or gallery builds. Cross‑chain support means a single integration covers multiple networks, and their SDKs for JavaScript, Python, and Unity let you get prototypes live in days.
Moralis handles pagination, rate limits, and retries for you, so you can focus on UX rather than backend plumbing.
Drawbacks
Moralis simplifies data access, but overly custom data models may still require dedicated backend logic.
Large-scale streaming or high concurrency workloads often push teams toward enterprise plans, affecting cost.
In peak network conditions, near-real-time indexing can lag by a few seconds, which may not suffice for ultra-low-latency trading applications.
The Graph – Subgraphs for Custom Indexing
Overview
When you need bespoke data models, The Graph shines. Define a subgraph by writing a GraphQL schema that maps smart contract events to entities, deploy it to the hosted service, and instantly get a GraphQL endpoint that answers complex queries in milliseconds.
Once you outgrow the hosted tier, you can migrate to the decentralized network, where indexers stake GRT tokens to serve queries, and curators signal popular subgraphs, ensuring high availability and censorship resistance.
Built-in features include full‑text search, time series aggregates for hourly or daily snapshots, and subscription support for live updates.
Whether you’re building DAO dashboard tools, NFT rarity explorers, or custom DeFi analytics, The Graph removes the pain of writing and maintaining subsecond query layers, letting you focus on domain logic instead of data plumbing.
Drawbacks
Writing and maintaining subgraphs adds development overhead, requiring familiarity with GraphQL and schema design.
For large or complex contracts, initial indexing can take significant time, sometimes minutes or hours.
Costs can accumulate if your subgraphs see heavy query traffic, especially on the decentralized network where query fees apply.
Covalent – Unified REST for On‑Chain Data
Overview
Covalent’s Unified API abstracts away 210+ blockchains behind consistent REST endpoints. Rather than learning a dozen JSON schemas, you call one endpoint for token balances, another for historical transactions (with decoded logs and internal traces), and another for NFT ownership and metadata.
Their GoldRush SDKs include TypeScript and Python clients, plus React components for portfolio tables, charts, and wallet explorers.
Covalent’s network of CQT‑staked nodes powers a SOC 2 Type II‑compliant service that guarantees data integrity and uptime. Unique offerings like the Wayback Machine archive rollup chain data pre‑ and post‑upgrade, making long‑term analytics simple.
Enterprises use Covalent for multi‑chain portfolio management, on‑chain compliance reporting, and transaction forensics – all without standing up bespoke indexers.
Drawbacks
Covalent’s data normalization may lack the detail some enterprise users require – custom internal traces or complex event decoding might still need bespoke processing.
The normalization pipeline introduces slight latency compared to direct node queries. And while Covalent ensures reliability, you relinquish control over indexing logic and data freshness.
Etherscan – Explorer‑Grade Blockchain Data
Overview
With Etherscan’s API, you can fetch account balances, token transfers, internal transaction traces, contract ABIs, and gas metrics via simple HTTP calls. Version 2 extends support to over 50 chains – Ethereum mainnet, Goerli, BSC, Arbitrum, and more – under one API key and unified rate limits.
Free tiers provide up to 5 calls/sec and 100,000 calls/day; PRO plans bump that to 30 calls/sec and 1.5 million calls/day, plus bulk data export endpoints and priority support. For compliance audits, wallet trackers, or on‑chain analytics that need explorer‑backed accuracy without self‑hosting, Etherscan’s API is a dependable choice.
Drawbacks
Free rate limits can quickly become a bottleneck for analytics-heavy applications, forcing upgrades to paid tiers.
Etherscan only exposes data visible in its explorer – no additional enrichment or custom fields.
Bulk data export capabilities and priority support remain behind proprietary PRO plans, limiting flexibility for budget-conscious projects.
Chainlink – Secure Oracles & Off‑Chain Compute
Overview
Chainlink sits at the heart of secure off‑chain data delivery. The Functions framework lets you run serverless JavaScript jobs off‑chain – fetch weather data, sports scores, or financial feeds – compute custom metrics, and return cryptographically signed results back to your smart contracts.
Their ANY API adapter supports REST, RSS, WebSocket, and more, making almost any external data source available on-chain.
Chainlink’s Price Feeds aggregate data from multiple sources every few seconds, delivering tamper‑proof reference prices for hundreds of assets. For gaming and NFT drops, the VRF (Verifiable Random Function) provides on‑chain randomness that’s provably fair.
Node operators stake LINK tokens to secure the network, and open‑source reference implementations ensure anyone can audit or run a node. If your dApp needs trustworthy off‑chain inputs or decentralized compute, Chainlink is the de facto standard.
Drawbacks
Integrating serverless Functions involves managing subscriptions and ensuring sufficient LINK token funding, adding operational complexity.
Each oracle call introduces latency – typically several seconds – so it’s less suited for ultra-fast on-chain data needs. LINK staking and node operator fees add ongoing costs that must be factored into your economic model.
Binance API – Custodial Trading & Market Data
Overview
Binance’s API covers spot, margin, futures, and options trading; account and wallet management; and market data streams. REST endpoints handle order placement, cancellation, and balance queries.
WebSockets deliver live order books, trades, and user data. A FIX 4.4 interface provides low-latency access for institutions.
Drawbacks
By its custodial nature, unlike ChangeNOW’s API, Binance requires users to trust the exchange with their assets, introducing counterparty risk.
Regulatory shifts can impact access or available features in certain regions, exposing you and your users to compliance challenges.
Aggressive trading bots must carefully manage rate limits and may need to subscribe to VIP tiers for high-frequency strategies.
WalletConnect – Decentralized Wallet Interaction
Overview
WalletConnect is an open protocol that allows dApps to connect to wallets on mobile or desktop via QR code scanning or deep linking.
It supports hundreds of wallets, including MetaMask, Trust Wallet, and Rainbow, providing a secure channel for signing transactions and messages without embedding private keys or SDKs directly in your frontend.
Drawbacks
While WalletConnect simplifies wallet integration, it relies on third-party wallets means you’re subject to the performance of others.
Connections aren’t stable across different conditions, leading to occasional timeouts or QR code mismatches.
Additionally, developers must handle session persistence and error recovery logic client-side, adding some frontend complexity.
Web3.Storage – Decentralized File Storage
Overview
Web3.Storage is a hosted service built on IPFS and Filecoin that lets you store and retrieve user-generated files—images, documents, metadata—via a simple REST API.
You upload files (which return a content identifier, or CID) and retrieve them on-demand from a decentralized storage network, ensuring redundancy, censorship resistance, and data permanence.
Drawbacks
Using Web3.Storage involves storage costs denominated in Filecoin, which can fluctuate and complicate budgeting.
Retrieval speeds depend on network availability and caching layers, so some files may load more slowly than with centralized CDNs.
Finally, while CIDs guarantee content integrity, you must manage pinning strategies or rely on the service’s retention policies to ensure long-term availability.
Conclusion
No matter where you sit in the Web3 ecosystem – wallet builder, DeFi innovator, NFT curator, or enterprise integrator – these ten APIs form the backbone of modern dApps.
They let you build complex features without server farms, scale seamlessly across networks, and deliver secure, reliable experiences to your users.
Pick the right combination, and you’ll be shipping production‑grade Web3 applications in no time.
