Testnets, RPCs, faucets, and wallets across 51+ blockchains. One hub. Zero noise.
Chains
51
Categories
4
Resource pages
191+
The Web3 Builder Hub is a curated index of developer resources across 51 blockchains. It covers four categories: testnet configurations, RPC endpoints, testnet faucets, and wallet compatibility. Each chain has a dedicated page listing verified links, network parameters, and setup instructions for that specific network. Each category has a landing page aggregating resources across all 51 chains.
The hub exists because Web3 developer tooling is fragmented. Every chain maintains its own documentation site, its own faucet infrastructure, its own list of supported RPC providers, and its own wallet configuration guides. Chain IDs, RPC URLs, block explorers, and bridge contracts are scattered across dozens of sources. A developer working on Arbitrum, Base, and Polygon simultaneously has to check three different documentation sites to find the correct Sepolia testnet RPC, the right faucet, and the chain ID for wallet configuration. The Builder Hub consolidates that into a single reference.
The directory is structured in two dimensions. Chain pages (Ethereum, Solana, Arbitrum, Sui, etc.) show all four resource categories for a single network. Category pages (testnets, RPCs, faucets, wallets) show a single resource type across all 51 chains. Both views link to the same underlying data. This means a search for "Base Sepolia RPC" and a search for "all EVM testnet RPCs" both land on maintained, verified content.
A testnet is a separate blockchain network that mirrors mainnet functionality using tokens with no monetary value. Developers deploy smart contracts, simulate transactions, test gas estimation, and debug reverts on testnets before committing real assets on mainnet. Without testnets, every bug costs money.
Testnet architectures vary. Ethereum's Sepolia is a proof-of-stake network that replaced the older Goerli testnet. Holesky runs as a separate beacon chain testnet for staking and validator testing. Solana uses Devnet (persistent, reset periodically) and Testnet (validator performance testing). Cosmos SDK chains typically run their own independent testnets with separate chain IDs and genesis files. L2 testnets (Arbitrum Sepolia, Base Sepolia, OP Sepolia) settle to Ethereum Sepolia, so their state depends on the L1 testnet remaining operational.
Deprecation is a recurring problem. Ropsten, Rinkeby, Kovan, and Goerli are all deprecated. Projects that hardcoded testnet configurations had to migrate. Sepolia is now the standard EVM testnet, but individual L2s may introduce and retire their own test networks independently. Key parameters to verify for any testnet: chain ID, block time, finality model, which EIPs are supported, and whether the network has a reliable block explorer.
Multi-chain applications complicate testing. If a protocol deploys on Ethereum mainnet and bridges to Arbitrum and Base, the developer needs testnet environments for all three, with a working bridge between them. L2 testnets that settle to Sepolia support this, but cross-chain message testing remains one of the harder parts of multi-chain development. Testnet directory.
An RPC endpoint is a URL that applications use to read from and write to a blockchain. The interface is JSON-RPC: the client sends a JSON payload with a method name and parameters, the node processes it, and returns the result. Core methods include eth_call (read contract state without a transaction), eth_getBalance (check an address's native token balance), eth_sendRawTransaction (submit a signed transaction), and eth_getLogs (retrieve event logs filtered by address, topic, or block range). Non-EVM chains use different interfaces: Solana has its own JSON-RPC spec, Cosmos chains use gRPC and REST, Substrate chains use a WebSocket-based API.
Public RPCs are free endpoints maintained by chain foundations or community operators. They have rate limits (typically 10 to 100 requests per second), no uptime guarantees, and limited historical data. Private RPC providers (Alchemy, Infura, QuickNode, Blast API, dRPC, Chainstack) offer dedicated throughput, WebSocket connections for streaming events, archive node access for querying historical state at any block height, and SLA-backed availability. Production applications and analytics pipelines require private RPCs. Development and testing can often use public endpoints.
The distinction between full nodes and archive nodes matters for anyone building analytics or block explorers. A full node stores the current state and recent blocks. An archive node stores every historical state trie, allowing queries like "what was this contract's storage slot at block 15,000,000." Archive nodes require significantly more storage (Ethereum archive nodes exceed 15 TB) and most free RPC providers do not offer archive access.
WebSocket connections (wss://) allow the client to subscribe to new blocks, pending transactions, or specific contract events in real time. HTTP connections require polling. For applications that need to react to on-chain events within seconds (liquidation bots, MEV searchers, real-time dashboards), WebSocket RPCs are necessary. For batch data retrieval or occasional reads, HTTP is sufficient. Self-hosted nodes (Geth, Reth, Nethermind for execution; Lighthouse, Prysm, Teku for consensus) eliminate provider dependencies but require infrastructure maintenance. RPC directory.
A faucet is a service that distributes test tokens to developer wallets. Deploying a contract on Sepolia costs test ETH for gas. Interacting with the deployed contract costs more test ETH. Without a faucet, developers cannot test anything. Most faucets distribute between 0.01 and 0.5 test ETH per request, with cooldown periods of 24 hours between claims.
Authentication requirements vary. Some faucets are open: paste an address, receive tokens. Others require signing in with a GitHub or Google account. Alchemy's Sepolia faucet requires an Alchemy account. PoW faucets make you solve a mining puzzle to prove you are not a bot. The anti-abuse measures exist because bots drain open faucets within hours of deployment, leaving real developers with no tokens.
Multi-chain development requires faucets for each target network. Testing on Arbitrum Sepolia, Base Sepolia, and OP Sepolia means three separate faucet requests. An alternative for L2 testnets: get Sepolia ETH from one faucet, then bridge it to the L2 testnet using the chain's official bridge. This works because L2 testnets settle to Ethereum Sepolia, so the bridge infrastructure operates on testnet as well. For non-EVM chains, faucet infrastructure is chain-specific: Solana Devnet has its own airdrop command (solana airdrop 2), Cosmos testnets use Discord bots, and Sui has a CLI faucet. Faucet directory.
Browser extension wallets are the primary interface between a developer and a blockchain during development. MetaMask is the standard for EVM chains. It injects a provider object into the browser's JavaScript context, which dApps use to request account access, sign transactions, and switch networks. Rabby supports most EVM networks and adds transaction simulation before signing. Both allow adding custom RPC URLs, which is required for connecting to testnets and L2 networks not included in the wallet's default network list.
Adding a custom network to MetaMask or Rabby requires four values: the RPC URL, chain ID, currency symbol, and block explorer URL. Getting any of these wrong results in failed transactions or connections to the wrong network. The Builder Hub's RPC pages list these values for every supported chain, eliminating the need to hunt through documentation.
Chain-specific wallets serve non-EVM ecosystems. Phantom is the standard wallet for Solana. Keplr handles Cosmos SDK chains (Cosmos Hub, Osmosis, Sei, Berachain). Polkadot.js covers Substrate-based networks. Sui Wallet and Martian handle Move chains. For development teams building cross-chain applications, maintaining multiple wallets with multiple accounts on multiple networks is unavoidable.
Programmatic wallets are used in automated testing and CI/CD pipelines. In ethers.js, new Wallet(privateKey) creates a signer that can submit transactions without a browser extension. Viem's privateKeyToAccount does the same. Hardhat and Foundry both support configuring test accounts with private keys for scripted deployments. Hardware wallets (Ledger, Trezor) are relevant for testing multisig flows and production deployment signing, where the deployer key should not exist as plaintext on a development machine. Wallet directory.
The Builder Hub is backed by a Notion CMS. Each chain and each resource category exists as a structured page in Notion. The DIA team maintains these pages directly: adding new chains at testnet or mainnet launch, updating RPC URLs when providers change endpoints, removing faucet links that go offline, and reflecting wallet support changes as extensions add or drop networks.
Verification is manual. RPC endpoints are tested for availability and correct chain ID responses. Faucet links are checked for functionality and token distribution. Wallet listings reflect current compatibility as confirmed in the wallet's documentation or release notes. Testnet configurations are validated against the chain's official documentation, including chain ID, block explorer URL, and native currency symbol.
Content is published through DIA's infrastructure with ISR (Incremental Static Regeneration) on a 60-second revalidation cycle. When the Notion source is updated, the next page request after the revalidation window triggers a rebuild with fresh data. This means changes propagate to the live site within minutes of being saved in Notion, without requiring a full deployment.
A testnet is a separate blockchain network that mirrors mainnet functionality using tokens with no monetary value. Developers deploy and test smart contracts, simulate transactions, and debug applications on testnets before mainnet deployment. Ethereum uses Sepolia and Holesky. Solana uses Devnet. Base uses Base Sepolia. Most L2s run Sepolia-based testnets.
An RPC (Remote Procedure Call) endpoint is a URL that applications use to communicate with a blockchain node. Read requests return balances, transaction data, and contract state. Write requests submit transactions and deploy contracts. Public RPCs are free but rate-limited, typically 10-100 requests per second. Private providers (Alchemy, Infura, QuickNode) offer higher throughput, WebSocket support, and archive node access with SLA-backed uptime.
Testnet faucets distribute free test tokens to developer wallets. Connect a wallet or paste an address, and the faucet sends test ETH, SOL, or the chain's native token. Most faucets enforce daily limits and cooldown periods. Some require a minimum mainnet balance or social account verification to prevent abuse.
MetaMask is the standard wallet for EVM chains (Ethereum, Arbitrum, Base, Polygon, Optimism). Phantom handles Solana. Keplr handles Cosmos SDK chains. For multi-chain development, Rabby supports most EVM networks. Choose based on the target chain and whether hardware wallet integration is required.
51 blockchains including Ethereum, Solana, Arbitrum, Base, Polygon, Optimism, Avalanche, zkSync, Starknet, NEAR, Sui, Aptos, TON, Cardano, Polkadot, Cosmos Hub, Berachain, Monad, and others. Each chain has pages for testnets, RPC endpoints, faucets, and wallets.
Public RPCs are free endpoints maintained by chain foundations or community operators. They have rate limits and no uptime guarantees. Private RPCs from providers like Alchemy, Infura, or QuickNode offer dedicated throughput, WebSocket connections, archive node access, and SLA-backed availability. Production applications typically require private RPCs.
Open wallet settings, navigate to Networks, and add a new network. Required fields: RPC URL, chain ID, currency symbol, and block explorer URL. The RPC pages in this hub list these values for every supported chain.
The DIA team curates every resource by hand. RPC endpoints are called and checked for a response and the expected chain ID, faucet links are used once to confirm they still deliver tokens, and wallet listings are checked against each wallet's own documentation. Resource tables are maintained in Notion; the page copy around them lives in this site's repository as markdown. There is no automated uptime monitor, so updates happen on a rolling basis as chains launch new testnets or deprecate old ones.