Minimal library for Ethereum transactions, addresses and smart contracts.
- 🔓 Secure: 3 deps, audited noble cryptography, no network code
- 🔻 Tree-shakeable: unused code is excluded from your builds
- 🔍 Reliable: 150MB of test vectors from EIPs, ethers and viem
- ✍️ Create, sign and decode transactions using human-readable hints
- 🌍 Fetch balances and history from an archive node
- 🆎 Call smart contracts: Chainlink and Uniswap APIs are included
- 🦺 Typescript-friendly ABI, RLP and SSZ decoding
- 🪶 1200 lines for core functionality
Check out article ZSTs, ABIs, stolen keys and broken legs about caveats of secure ABI parsing found during development of the library.
Check out all web3 utility libraries: ETH, BTC, SOL
npm install micro-eth-signer
We support all major platforms and runtimes. For Deno, ensure to use npm specifier. For React Native, you may need a polyfill for getRandomValues. If you don't like NPM, a standalone eth-signer.js is also available.
- Create random wallet
- Transactions: create, sign
- Addresses: create, checksum
- Network and smart contracts
- Parsing
- Utilities
- Security
- Performance
- License
import { addr } from 'micro-eth-signer';
const random = addr.random(); // Secure: uses CSPRNG
console.log(random.privateKey, random.address);
// '0x17ed046e6c4c21df770547fad9a157fd17b48b35fe9984f2ff1e3c6a62700bae'
// '0x26d930712fd2f612a107A70fd0Ad79b777cD87f6'
import { Transaction, weigwei, weieth } from 'micro-eth-signer';
const tx = Transaction.prepare({
to: '0xdf90dea0e0bf5ca6d2a7f0cb86874ba6714f463e',
value: weieth.decode('1.1'), // 1.1eth in wei
maxFeePerGas: weigwei.decode('100'), // 100gwei in wei (priority fee is 1 gwei)
nonce: 0n,
});
// Uses `random` from example above. Alternatively, pass 0x hex string or Uint8Array
const signedTx = tx.signBy(random.privateKey);
console.log('signed tx', signedTx, signedTx.toHex());
console.log('fee', signedTx.fee);
We support legacy, EIP2930, EIP1559 and EIP4844 (Dencun / Cancun) transactions.
import { addr } from 'micro-eth-signer';
const priv = '0x0687640ee33ef844baba3329db9e16130bd1735cbae3657bd64aed25e9a5c377';
const pub = '030fba7ba5cfbf8b00dd6f3024153fc44ddda93727da58c99326eb0edd08195cdb';
const nonChecksummedAddress = '0x0089d53f703f7e0843953d48133f74ce247184c2';
const checksummedAddress = addr.addChecksum(nonChecksummedAddress);
console.log(
checksummedAddress, // 0x0089d53F703f7E0843953D48133f74cE247184c2
addr.isValid(checksummedAddress), // true
addr.isValid(nonChecksummedAddress), // also true
addr.fromPrivateKey(priv),
addr.fromPublicKey(pub)
);
A common problem in web3 libraries is how complex they are to audit with regards to network calls.
In eth-signer, all network calls are done with user-provided function, conforming to built-in fetch()
:
- This makes library network-free, which simplifies auditability
- User fully controls all network requests
It's recommended to use micro-ftch, which works on top of fetch and implements killswitch, logging, concurrency limits and other features.
Most APIs (chainlink, uniswap) expect instance of ArchiveNodeProvider. The call stack would look like this:
Chainlink
=>ArchiveNodeProvider
=>jsonrpc
=>fetch
To initialize ArchiveNodeProvider, do the following:
// Requests are made with fetch(), a built-in method
import { jsonrpc } from 'micro-ftch';
import { ArchiveNodeProvider } from 'micro-eth-signer/net';
const RPC_URL = 'http://localhost:8545';
const prov = new ArchiveNodeProvider(jsonrpc(fetch, RPC_URL));
// Example using mewapi RPC
const RPC_URL_2 = 'https://nodes.mewapi.io/rpc/eth';
const prov2 = new ArchiveNodeProvider(
jsonrpc(fetch, RPC_URL_2, { Origin: 'https://www.myetherwallet.com' })
);
const addr = '0xd8da6bf26964af9d7eed9e03e53415d37aa96045';
const block = await prov.blockInfo(await prov.height());
console.log('current block', block.number, block.timestamp, block.baseFeePerGas);
console.log('info for addr', addr, await prov.unspent(addr));
// Other methods of ArchiveNodeProvider:
// blockInfo(block: number): Promise<BlockInfo>; // {baseFeePerGas, hash, timestamp...}
// height(): Promise<number>;
// internalTransactions(address: string, opts?: TraceOpts): Promise<any[]>;
// ethLogsSingle(topics: Topics, opts: LogOpts): Promise<Log[]>;
// ethLogs(topics: Topics, opts?: LogOpts): Promise<Log[]>;
// tokenTransfers(address: string, opts?: LogOpts): Promise<[Log[], Log[]]>;
// wethTransfers(address: string, opts?: LogOpts): Promise<[Log[]]>;
// txInfo(txHash: string, opts?: TxInfoOpts): Promise<{
// type: "legacy" | "eip2930" | "eip1559" | "eip4844"; info: any; receipt: any; raw: string | undefined;
// }>;
// tokenInfo(address: string): Promise<TokenInfo | undefined>;
// transfers(address: string, opts?: TraceOpts & LogOpts): Promise<TxTransfers[]>;
// allowances(address: string, opts?: LogOpts): Promise<TxAllowances>;
// tokenBalances(address: string, tokens: string[]): Promise<Record<string, bigint>>;
Basic data can be fetched from any node.
Historical balances, transactions and others can only be fetched from an archive node, such as Erigon or Reth.
import { Chainlink } from 'micro-eth-signer/net';
const link = new Chainlink(prov);
const btc = await link.coinPrice('BTC');
const bat = await link.tokenPrice('BAT');
console.log({ btc, bat }); // BTC 19188.68870991, BAT 0.39728989 in USD
import { ENS } from 'micro-eth-signer/net';
const ens = new ENS(prov);
const vitalikAddr = await ens.nameToAddress('vitalik.eth');
Btw cool tool, glad you built it!
Uniswap Founder
Swap 12.12 USDT to BAT with uniswap V3 defaults of 0.5% slippage, 30 min expiration.
import { tokenFromSymbol } from 'micro-eth-signer/abi';
import { UniswapV3 } from 'micro-eth-signer/net'; // or UniswapV2
const USDT = tokenFromSymbol('USDT');
const BAT = tokenFromSymbol('BAT');
const u3 = new UniswapV3(prov); // or new UniswapV2(provider)
const fromAddress = '0xd8da6bf26964af9d7eed9e03e53415d37aa96045';
const toAddress = '0xd8da6bf26964af9d7eed9e03e53415d37aa96045';
const swap = await u3.swap(USDT, BAT, '12.12', { slippagePercent: 0.5, ttl: 30 * 60 });
const swapData = await swap.tx(fromAddress, toAddress);
console.log(swapData.amount, swapData.expectedAmount, swapData.allowance);
The transaction sent ERC-20 USDT token between addresses. The library produces a following hint:
Transfer 22588 USDT to 0xdac17f958d2ee523a2206206994597c13d831ec7
import { decodeTx } from 'micro-eth-signer/abi';
const tx =
'0xf8a901851d1a94a20082c12a94dac17f958d2ee523a2206206994597c13d831ec780b844a9059cbb000000000000000000000000dac17f958d2ee523a2206206994597c13d831ec7000000000000000000000000000000000000000000000000000000054259870025a066fcb560b50e577f6dc8c8b2e3019f760da78b4c04021382ba490c572a303a42a0078f5af8ac7e11caba9b7dc7a64f7bdc3b4ce1a6ab0a1246771d7cc3524a7200';
// Decode tx information
deepStrictEqual(decodeTx(tx), {
name: 'transfer',
signature: 'transfer(address,uint256)',
value: {
to: '0xdac17f958d2ee523a2206206994597c13d831ec7',
value: 22588000000n,
},
hint: 'Transfer 22588 USDT to 0xdac17f958d2ee523a2206206994597c13d831ec7',
});
Or if you have already decoded tx:
import { decodeData } from 'micro-eth-signer/abi';
const to = '0x7a250d5630b4cf539739df2c5dacb4c659f2488d';
const data =
'7ff36ab5000000000000000000000000000000000000000000000000ab54a98ceb1f0ad30000000000000000000000000000000000000000000000000000000000000080000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa96045000000000000000000000000000000000000000000000000000000006fd9c6ea0000000000000000000000000000000000000000000000000000000000000002000000000000000000000000c02aaa39b223fe8d0a0e5c4f27ead9083c756cc2000000000000000000000000106d3c66d22d2dd0446df23d7f5960752994d600';
const value = 100000000000000000n;
deepStrictEqual(decodeData(to, data, value, { customContracts }), {
name: 'swapExactETHForTokens',
signature: 'swapExactETHForTokens(uint256,address[],address,uint256)',
value: {
amountOutMin: 12345678901234567891n,
path: [
'0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2',
'0x106d3c66d22d2dd0446df23d7f5960752994d600',
],
to: '0xd8da6bf26964af9d7eed9e03e53415d37aa96045',
deadline: 1876543210n,
},
});
// With custom tokens/contracts
const customContracts = {
'0x106d3c66d22d2dd0446df23d7f5960752994d600': { abi: 'ERC20', symbol: 'LABRA', decimals: 9 },
};
deepStrictEqual(decodeData(to, data, value, { customContracts }), {
name: 'swapExactETHForTokens',
signature: 'swapExactETHForTokens(uint256,address[],address,uint256)',
value: {
amountOutMin: 12345678901234567891n,
path: [
'0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2',
'0x106d3c66d22d2dd0446df23d7f5960752994d600',
],
to: '0xd8da6bf26964af9d7eed9e03e53415d37aa96045',
deadline: 1876543210n,
},
hint: 'Swap 0.1 ETH for at least 12345678901.234567891 LABRA. Expires at Tue, 19 Jun 2029 06:00:10 GMT',
});
Decoding the event produces the following hint:
Allow 0xe592427a0aece92de3edee1f18e0157c05861564 spending up to 1000 BAT from 0xd8da6bf26964af9d7eed9e03e53415d37aa96045
import { decodeEvent } from 'micro-eth-signer/abi';
const to = '0x0d8775f648430679a709e98d2b0cb6250d2887ef';
const topics = [
'0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925',
'0x000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa96045',
'0x000000000000000000000000e592427a0aece92de3edee1f18e0157c05861564',
];
const data = '0x00000000000000000000000000000000000000000000003635c9adc5dea00000';
const einfo = decodeEvent(to, topics, data);
console.log(einfo);
The ABI is type-safe when as const
is specified:
import { createContract } from 'micro-eth-signer/abi';
const PAIR_CONTRACT = [
{
type: 'function',
name: 'getReserves',
outputs: [
{ name: 'reserve0', type: 'uint112' },
{ name: 'reserve1', type: 'uint112' },
{ name: 'blockTimestampLast', type: 'uint32' },
],
},
] as const;
const contract = createContract(PAIR_CONTRACT);
// Would create following typescript type:
{
getReserves: {
encodeInput: () => Uint8Array;
decodeOutput: (b: Uint8Array) => {
reserve0: bigint;
reserve1: bigint;
blockTimestampLast: bigint;
};
}
}
We're parsing values as:
// no inputs
{} -> encodeInput();
// single input
{inputs: [{type: 'uint'}]} -> encodeInput(bigint);
// all inputs named
{inputs: [{type: 'uint', name: 'lol'}, {type: 'address', name: 'wut'}]} -> encodeInput({lol: bigint, wut: string})
// at least one input is unnamed
{inputs: [{type: 'uint', name: 'lol'}, {type: 'address'}]} -> encodeInput([bigint, string])
// Same applies for output!
There are following limitations:
- Fixed size arrays can have 999 elements at max: string[], string[1], ..., string[999]
- Fixed size 2d arrays can have 39 elements at max: string[][], string[][1], ..., string[39][39]
- Which is enough for almost all cases
- ABI must be described as constant value:
[...] as const
- We're not able to handle contracts with method overload (same function names with different args) — the code will still work, but not types
Check out src/net/ens.ts
for type-safe contract execution example.
We implement RLP in just 100 lines of code, powered by packed:
import { RLP } from 'micro-eth-signer/rlp';
RLP.decode(RLP.encode('dog'));
Simple serialize (SSZ) is the serialization method used on the Beacon Chain. We implement RLP in just 900 lines of code, powered by packed:
import * as ssz from 'micro-eth-signer/ssz';
EIP-712 is not supported yet.
import { addr, messenger } from 'micro-eth-signer';
const rand = addr.random();
const msg = 'noble';
const sig = messenger.sign(msg, rand.privateKey);
const isValid = messenger.verify(sig, msg, address);
import { addr, Transaction, weigwei, weieth } from 'micro-eth-signer';
const privKey = '0x6b911fd37cdf5c81d4c0adb1ab7fa822ed253ab0ad9aa18d77257c88b29b718e';
const senderAddr = addr.fromPrivateKey(privKey);
const unsignedTx = Transaction.prepare({
to: '0xdf90dea0e0bf5ca6d2a7f0cb86874ba6714f463e',
maxFeePerGas: weigwei.decode('100'), // 100 gwei in wei
value: weieth.decode('1.1'), // 1.1 eth in wei
nonce: 0n,
});
const CURRENT_BALANCE = '1.7182050000017'; // eth
const txSendingWholeBalance = unsignedTx.setWholeAmount(weieth.decode(CURRENT_BALANCE));
Creates transaction which sends whole account balance. Does two things:
amount = accountBalance - maxFeePerGas * gasLimit
maxPriorityFeePerGas = maxFeePerGas
Every eth block sets a fee for all its transactions, called base fee. maxFeePerGas indicates how much gas user is able to spend in the worst case. If the block's base fee is 5 gwei, while user is able to spend 10 gwei in maxFeePerGas, the transaction would only consume 5 gwei. That means, base fee is unknown before the transaction is included in a block.
By setting priorityFee to maxFee, we make the process deterministic:
maxFee = 10, maxPriority = 10, baseFee = 5
would always spend 10 gwei.
In the end, the balance would become 0.
WARNING: using the method would decrease privacy of a transfer, because payments for services have specific amounts, and not the whole amount.
Main points to consider when auditing the library:
- ABI correctness
- All ABI JSON should be compared to some external source
- There are different databases of ABI: one is hosted by Etherscan, when you open contract page
- Network access
- There must be no network calls in the library
- Some functionality requires network: these need external network interface, conforming to
Web3Provider
createContract(abi)
should create purely offline contractcreateContract(abi, net)
would create contract that calls network usingnet
, using external interface
- Skipped test vectors
- There is
SKIPPED_ERRORS
, which contains list of test vectors from other libs that we skip - They are skipped because we consider them invalid, or so
- If you believe they're skipped for wrong reasons, investigate and report
- There is
The library is cross-tested against other libraries (last update on 25 Feb 2024):
- ethereum-tests v13.1
- ethers 6.11.1
- viem v2.7.13
Transaction signature matches noble-curves
sign()
speed,
which means over 4000 times per second on macs.
The first call of sign
will take 20ms+ due to noble-curves secp256k1 utils.precompute
.
To run benchmarks, execute npm run bench
.
Make sure to use recursive cloning for tests:
git clone --recursive https://github.com/paulmillr/micro-eth-signer.git
MIT License
Copyright (c) 2021 Paul Miller (https://paulmillr.com)