/ Logging

Small and extensible logger which prints beautiful logs with flutter

Small and extensible logger which prints beautiful logs with flutter


Small, easy to use and extensible logger which prints beautiful logs.
Inspired by logger for Android.

Getting Started

Just create an instance of Logger and start logging:

var logger = Logger();

logger.d("Logger is working!");

Instead of a string message, you can also pass other objects like List, Map or Set.


Log Console

If you are creating a Flutter app, you can use the logger_flutter extension. Shake the phone to show an on device console.


Log level

You can log with different levels:

logger.v("Verbose log");

logger.d("Debug log");

logger.i("Info log");

logger.w("Warning log");

logger.e("Error log");

logger.wtf("What a terrible failure log");

To show only specific log levels, you can set:

Logger.level = Level.warning;

This hides all verbose, debug and info log events.


When creating a logger, you can pass some options:

var logger = Logger(
  filter: null, // Use the default LogFilter (-> only log in debug mode)
  printer: PrettyPrinter(), // Use the PrettyPrinter to format and print log
  output: null, // Use the default LogOutput (-> send everything to console)

If you use the PrettyPrinter, there are more options:

var logger = Logger(
  printer: PrettyPrinter(
    methodCount: 2, // number of method calls to be displayed
    errorMethodCount: 8, // number of method calls if stacktrace is provided
    lineLength: 120, // width of the output
    colors: true, // Colorful log messages
    printEmojis: true, // Print an emoji for each log message
    printTime: false // Should each log print contain a timestamp


The LogFilter decides which log events should be shown and which don't.

The default implementation (DebugFilter) shows all logs with level >= Logger.level while in debug mode. In release mode all logs are omitted.

You can create your own LogFilter like this:

class MyFilter extends LogFilter {
  bool shouldLog(LogEvent event) {
    return true;

This will show all logs even in release mode. (NOT a good idea)


The LogPrinter creates and formats the output, which is then sent to the LogOutput.

You can implement your own LogPrinter. This gives you maximum flexibility.

A very basic printer could look like this:

class MyPrinter extends LogPrinter {
  void log(LogEvent event) {

Important: Every implementation has to send its output using the println() method.

If you created a cool LogPrinter which might be helpful to others, feel free to open a pull request. :)


LogOutput sends the log lines to the desired destination.

The default implementation (ConsoleOutput) send every line to the system console.

class ConsoleOutput extends LogOutput {
  void output(OutputEvent event) {
    for (var line in event.lines) {

Possible future LogOutputs could send to a file, firebase or to Logcat. Feel free to open pull requests.

logger_flutter extension

The logger_flutter package is an extension for logger. You can add it to any Flutter app. Just shake the phone to show the console.

  1. Add logger_flutter to your pubspec.yaml
  2. Add the following code into your widget tree
  child: Container() // Your widgets

More documentation coming soon.