The docs are wrong: https://github.com/jprichardson/node-jsonfile#writefilefilename-options-callback they don't describe the data argument, I assume it should be `writeFile(filename, obj, [options], callback)` Also, documented behaviour is > Pass in any fs.writeFile options That includes the string, 'utf-8', but passing in a string was broken by: https://github.com/jprichardson/node-jsonfile/commit/e4d8e67a0c4c3630fd53c4d5bd22e3fec4c30a06