This is a zero-dependency and lightweight Solidity flattener. This tool combines any given Solidity file's dependency and prints out the value in the shell.
npm install -g flatsol
Compatible with truffle-flattener
Just intall it with npm in your truffle project and run
flatsol ./contracts/Token.sol > ./contracts/.Token.flat.sol
Aliased imports (eg: import {symbol1 as alias, symbol2} from "filename";) are not supported by flatsol.