Compile, deploy, run, explain, and differentially compare Solidity functions without starting a local JSON-RPC node. EchoEVM keeps execution evidence next to the source and exposes the complete opcode trace only when requested.

Two-minute start

Install the extension.
Run EchoEVM: Setup and Diagnose Toolchain. On macOS, the extension installs EchoEVM from smallyunet/tap/echoevm with Homebrew. On Linux and Windows, it downloads the matching CLI from GitHub Releases and verifies it against the published SHA256SUMS file.
Run EchoEVM: Open Getting Started Example.
Choose Run Example, then Show Trace.

The EchoEVM status-bar item shows whether the CLI and compiler are ready. Click it at any time to diagnose or repair the toolchain.

Requirements

On macOS, setup requires Homebrew and installs the public smallyunet/tap/echoevm formula. The extension stores the formula's absolute executable path so it also works when VS Code is launched outside a shell. On Linux and Windows, the extension installs a release-matched EchoEVM CLI into its private global storage. It discovers workspace-local node_modules/.bin/solc and solcjs on macOS and Linux, then falls back to its bundled solc-js 0.8.30 compiler. Foundry workspaces use an installed SVM compiler matching solc_version or a semantic solc pin before those fallbacks. The CLI reads foundry.toml and remappings.txt for import remappings, optimizer settings, optimizer runs, and via_ir. On Windows, npm .cmd launchers are skipped and the bundled compiler is used. You can select a native compiler through the setup command or configure echoevm.executablePath and echoevm.solcPath.

For Remote SSH, Dev Containers, and WSL, tools are resolved and managed in the remote extension runtime rather than on the local desktop.

Usage

Open a trusted workspace and a .sol file.
Run EchoEVM: Run Solidity Function or EchoEVM: Run and Compare with Geth.
Select a deployable contract and ABI function.
Enter constructor and function arguments when prompted.
Review the result in the EchoEVM output channel. Run EchoEVM: Show Last Trace for the opcode table.

Source-aware execution evidence

Every Solidity function declaration has EchoEVM Run and Compare with Geth CodeLens actions. After a run, the extension:

shows the latest status and gas usage beside the relevant source line;
reports a concrete REVERT or fault in VS Code Problems;
fills the EchoEVM: Execution Evidence view with gas, state, comparison, and selected control/state-changing opcodes;
maps a terminal opcode or first divergence back to Solidity when the CLI provides a runtime source map; and
keeps the full opcode table available through Show Last Trace.

Inline results describe only the executed input. They are not static security findings. Disable them with echoevm.inlineResults, or disable function actions with echoevm.codeLens.

Trust and downloads

On macOS, EchoEVM delegates CLI installation to Homebrew using the fully qualified smallyunet/tap/echoevm formula. On Linux and Windows, it only downloads CLI assets from smallyunet/echoevm GitHub Releases and rejects a binary unless its SHA-256 digest matches that release's checksum manifest. The bundled compiler does not modify the workspace or global package manager. Projects that pin another compiler can select it explicitly. Non-Foundry workspaces can configure echoevm.remappings, echoevm.optimizerRuns, and echoevm.viaIR directly.

This release targets Cancun and does not provide Foundry cheatcodes, RPC forking, payable calls, or source-level breakpoints.