Blockchain

Foundry10.6k★

Foundry is a Rust-based smart contract development toolkit that replaced Hardhat for a lot of Solidity developers who wanted faster testing and native Solidity scripting. Write your tests in Solidity instead of JavaScript, and they run orders of magnitude faster. Apache 2.0. Four CLI tools: forge (build/test), cast (interact with contracts), anvil (local testnet), and chisel (Solidity REPL). The testing framework supports fuzz testing, invariant testing, and gas snapshots natively. Fully free. No paid tier, no hosted version. Install the CLI and go. The speed difference over Hardhat is not marginal; it's dramatic. Test suites that took minutes run in seconds. The Solidity-native testing means no context-switching between Solidity and JavaScript. Solo through large teams: free, no restrictions. The tooling is mature enough for production use at every scale. The catch: Foundry's Solidity-only testing means you lose access to Hardhat's JavaScript plugin ecosystem. If you need complex deployment scripts with off-chain logic, Hardhat's JavaScript flexibility is easier. The learning curve from Hardhat to Foundry is real: different testing patterns, different project structure. And if you're not in the EVM ecosystem, this is irrelevant.

Hardhat8.5k★

Hardhat is the standard Ethereum development environment that most Solidity developers reach for: a local testing chain, a compiler, a debugger, and a plugin ecosystem. It's the Node.js of blockchain development: a local testing chain, a compiler, a debugger, and a deployment pipeline all in one. Everything is free and open source. No paid tier, no cloud service, no premium plugins. The core team (Nomic Foundation) is funded by the Ethereum Foundation, not by charging developers. MIT-like license on most components. There's nothing to host. Hardhat runs locally as a Node.js package. npx hardhat gets you a project scaffold, a local Ethereum network for testing, and a compilation pipeline. It integrates with ethers.js, Viem, and every major Ethereum library. Solo developers: this is your starting point for Solidity development. The local network and console.log in Solidity (yes, really) make debugging so much faster than the alternatives. Small teams: Hardhat's plugin system lets you add gas reporting, contract verification, and coverage analysis. Larger teams: the Hardhat Ignition deployment system handles multi-step contract deployments across networks. The catch: Hardhat is Ethereum-specific. If you're building on Solana, Cosmos, or other chains, this isn't for you. And compilation speed on large projects can be slow. Foundry (written in Rust) compiles significantly faster.

ord4.0k★

Ord is the reference implementation for Bitcoin Ordinals, the protocol that lets you inscribe data directly onto individual satoshis. The package includes a CLI wallet, a block explorer, and indexing tools. Fully free, open source, and community-funded. Running ord requires a fully synced Bitcoin Core node with transaction indexing enabled: 1TB+ disk and days of initial sync. The CLI manages inscriptions and wallet operations. It processes every block as they come in, so you are committing to ongoing maintenance, not a set-it-and-forget-it setup. Bitcoin developers and anyone building on the Ordinals protocol need this. There is no real alternative because this is the reference implementation. If you are not specifically building on Bitcoin Ordinals, this is not relevant to you. Niche but exactly right for that niche. The catch: the block explorer renders untrusted HTML and JavaScript from inscriptions. The team warns about this explicitly. Host it with access controls, not publicly open.

stellar-core3.3k★

stellar-core is the node software for the Stellar payment network. Every computer that validates Stellar transactions runs it, agreeing with its peers on a shared ledger every five to seven seconds. Apache 2.0, free, and maintained by the Stellar Development Foundation. Most builders should not run it. That is Stellar's own advice. A validator should not be used for data access or transaction submission. App developers want Stellar RPC or Horizon, which bundle a captive copy of Core, or a hosted RPC provider. Run stellar-core when you issue an asset on the network and want a vote in how it is governed. Running a validator is real infrastructure. The documented spec is 8 vCPUs, 16 GB of RAM, and 100 GB of local NVMe, plus Postgres and mandatory NTP time sync. Stellar does not recommend Kubernetes for validators. Ubuntu LTS gets official packages, RPM distros do not. Becoming a Tier 1 organization means three geographically spread full validators at 99.9% uptime, and operators report roughly $160 to $1,800 a month for the three nodes. The catch: nothing in the docs mentions payment for validating. You run one to secure your own asset, support decentralization, and vote on protocol upgrades. Publishing a history archive from a big cloud provider adds egress bills on top.

web3.swift718★

Talking to Ethereum from an iOS app means signing transactions and calling contracts with no JavaScript runtime in sight. Web3.swift is the Swift library that handles that. It's the Swift equivalent of web3.js or ethers.js. MIT license. Provides typed Ethereum JSON-RPC calls, ABI encoding/decoding, contract interaction, and transaction signing from native Swift code. Works with any Ethereum node or provider (Infura, Alchemy, etc.). Fully free. Client library. Install via Swift Package Manager and use. No hosting, no paid tier. The catch: this library is effectively in maintenance mode with no recent activity. The Ethereum ecosystem moves fast (new EIPs, new standards, chain upgrades), and a dormant library risks falling behind. Check the last commit date before depending on this for production. If you need active development and broader chain support, consider using ethers.js via a JavaScript bridge or look at alternative Swift Ethereum libraries. The Swift blockchain development community is small, and your options are limited.

polyledger623★

PolyLedger pulls Polymarket's whole trade history into one file you can query with SQL. It hits the CLOB API for market and token metadata, streams OrderFilled events off Polygon, joins them, and writes it all into a single DuckDB database. Markets, tokens, raw fills, and a joined trades view, exportable to Parquet. The design choice worth noting is Envio HyperSync instead of a normal RPC node. No Alchemy or Infura key, no rate limit babysitting, and a free HyperSync token covers it. Python 3.11 or newer, pip install from a clone. It checkpoints as it goes, so an interrupted index resumes instead of restarting, and it indexes both the V1 and V2 exchange contracts so history does not stop at the contract migration. Anyone doing prediction market analytics, backtests, or research gets a working dataset in an afternoon instead of writing an indexer. MIT, no paid tier, nothing to host. The catch is that a free tier on somebody else's API is still a dependency. If HyperSync changes its limits or pricing, your pipeline changes with it, and there is no fallback path to a plain RPC node. Budget disk space too. Every fill on an active venue is not a small file.