TLDR tsconfig.json is the config file for every TypeScript project. It tells the TypeScript compiler what to check and how to build your code. Run tsc --init to create one. The key options you need to know are target , module , strict , outDir , and rootDir . Always turn on strict mode. It saves you from many bugs. What is tsconfig.json? tsconfig.json is a file that lives at the root of your TypeScript project. It controls how TypeScript compiles your code. When you run tsc in your terminal, Typ