Read the EVM without leaving your editor.
0xTools decodes function selectors, event topics and error selectors — and annotates gas inline — right inside VS Code. Plus security audits, one-click Anvil, and a full EVM toolbox.
$ 0xtools: start anvil
Listening on 127.0.0.1:8545
$ deploy Vault.sol
➜ Vault deployed 0x5FbD…0aa3
✓ 2 txs · block #3 · 0.0042 ETH gas
keystore: dev-wallet unlocked ✓
function deposit() external payable {⛽ 43,674
balances[msg.sender] += msg.value;
}
function withdraw(uint256) {⛽ 30,421
optimizer: −2,110 gas · use custom errors
unknown calldata
0x2e1a7d4d000000000000000000…0de0b6b3a7640000
withdraw(uint256 wad)
selector 0x2e1a7d4d · wad = 1.0 ETH · 4byte ✓
⚠ reentrancy withdraw() — L11 · external call before state write
⚠ missing event balances written, none emitted
✓ access control no unprotected selfdestruct
✓ ERC-20 compliant interface check passed
MEV: sandwich risk · slither: 0 high
> convert units
1 ether = 10¹⁸ wei · 21000 gwei = 0.000021 ETH
> keccak-256
transfer(address,uint256) → 0xa9059cbb
> CREATE2 address
salt 0x00…01 → 0x4f5B…9c21
The Solidity toolkit that lives in the editor.
Real gas, not guesses
Inline annotations from a three-tier backend (Rust runner → Forge → solc-js), plus optimizer suggestions, snapshots, branch comparison, deployment cost and a runtime profiler.
Every selector, named
Function selectors, event topics, error selectors and raw calldata decoded on hover — local 4-byte cache, collision detection, and a searchable signature database.
25+ analysis modules
Reentrancy, unchecked calls, access control, MEV risks, DeFi patterns, ERC-20/721/1155/4626 compliance, storage layout, call graphs — with quick fixes and a CLI audit mode.
One-click local chain
Start Anvil, deploy from a dashboard, run forge scripts with keystores, get test CodeLens pass/fail inline — plus a contract playground and interactive notebooks.
13 tools in the palette
ABI & calldata encode/decode, event log and raw-tx decoding, unit converter, keccak, storage slots, CREATE2 addresses, epoch times, checksums — no browser tabs.
Your whole toolchain
Foundry and Hardhat auto-detected; Slither, Mythril, Tenderly simulation, Cast, fork simulator and Etherscan verification wired into panels.
101 commands. One 998 KB VSIX.
nothing to hide — every chip links to its source file ↗
AI writes the contract. 0xTools keeps it honest.
Agents hallucinate selectors, gas numbers and security judgments. 0xTools hands them deterministic ground truth instead — as an MCP server for Claude Code / Cursor, and as native Copilot agent tools inside VS Code. Every AI call is logged and flashed in the status bar; one setting turns it all off.
>write a withdraw function for the vault and make sure it's safe
⏺ Writing Vault.withdraw()… then verifying with 0xTools
⚒ audit_solidity(source: Vault.sol)
⚠ high · reentrancy · L7 — external call before state change
⏺ Caught it — moving the balance write before the call (checks-effects-interactions), re-auditing… ✓ 0 high findings
⚒ compute_selector("withdraw(uint256)")
→ 0x2e1a7d4d · quoted exactly, not from memory
claude mcp add 0xtools -- node ./dist/cli/index.js mcp14 tools over stdio. An agent skill ships in skills/0xtools that teaches Claude when to call them.
8 language-model tools (#auditSolidity, #computeSelector…) register on install. A status-bar strip lights on every AI call, the “0xTools AI” output channel logs it, and sigscan.ai.enableTools is the kill switch.
Three steps. No marketplace.
We ship the VSIX directly while the marketplace listing is in the works. Same extension, zero middlemen.
Install it
code --install-extension 0xtools-0.0.6.vsixor: Extensions panel → ··· menu → “Install from VSIX…”
Open a .sol file
Gas annotations, selector hovers and the activity-bar dashboard light up automatically.