solc-js

0.4.24 verified Fri May 01 auth: no javascript

JavaScript bindings for the Solidity compiler, wrapping Emscripten-compiled binaries from solc-bin. The current stable version is 0.8.28 (as of 2025), with a release cadence following Solidity releases (monthly). Key differentiators: it is the official JS wrapper for the Solidity compiler, supports standard JSON I/O (compileStandard/compileStandardWrapper), legacy compile() API, and import callbacks for resolving dependencies. Alternative is solc-typed by TypeChain but this is the canonical package for compiling Solidity in Node.js and browser environments.

Common errors

error Error: require() of ES Module /path/to/solc/index.js from /path/to/app.js not supported. ↓

cause Using import solc from 'solc' in a CJS context, or using newer solc versions that are ESM-only.

fix

Use const solc = require('solc') for CJS, or update to bundler that supports ESM.

error TypeError: solc.compile is not a function ↓

cause Attempting to call compile on newer solc versions where compile is not exported (>=0.6.0).

fix

Use solc.compileStandardWrapper instead.

error TypeError: Cannot read properties of undefined (reading 'bytecode') ↓

cause Assuming output.contracts always exists; but if compilation fails, output may have errors instead.

fix

Check output.errors before accessing contracts.

Warnings

breaking In solc >=0.6.0, the old compile() API with object sources (e.g., solc.compile({sources:...}, optimizer, findImports)) is removed; use compileStandard or compileStandardWrapper instead. ↓

fix Use compileStandardWrapper with JSON string input as shown in quickstart.

deprecated The method compile() is deprecated in favor of compileStandardWrapper since version 0.4.11 and will be removed. ↓

fix Switch to compileStandardWrapper.

gotcha solc.compile() returns an object with 'errors' array of strings, but compileStandardWrapper returns a JSON string. Parsing the JSON string may throw if errors are present. ↓

fix Always wrap compileStandardWrapper output in try/catch or check for errors before parsing.

Install

npm install krzkaczor-solc

yarn add krzkaczor-solc

pnpm add krzkaczor-solc

Imports

solc
wrong
```
import solc from 'solc'
```
correct
```
const solc = require('solc')
```
solc is primarily CJS; ESM imports require named import (import solc from 'solc') in Node with esm flag or bundler, but default import works in TS with esModuleInterop.
compileStandard
wrong
```
const compileStandard = require('solc').compile
```
correct
```
const { compileStandard } = require('solc')
```
compileStandard is a separate function, not available in old versions (<0.4.11). Use compileStandardWrapper for broader compatibility.
version
wrong
```
const version = require('solc/version')
```
correct
```
const { version } = require('solc')
```
The version is a string. Access it via the module directly or solc.version.

Quickstart

Compiles a Solidity contract using the standard JSON input/output API (compile wrapper with JSON string).

const solc = require('solc');
const input = {
  language: 'Solidity',
  sources: {
    'test.sol': {
      content: 'contract C { function f() public pure returns (uint) { return 1; } }'
    }
  },
  settings: {
    outputSelection: {
      '*': {
        '*': ['*']
      }
    }
  }
};
const output = JSON.parse(solc.compile(JSON.stringify(input)));
if (output.errors) {
  output.errors.forEach(e => console.error(e.formattedMessage));
} else {
  console.log(output.contracts['test.sol'].C.abi);
}