Eh! Of what use is a new-born baby? -- Benjamin Franklin
Lightweight toolkit for working with Arcaea File Format (AFF) chart files in .NET.
You can download the latest release from the Releases page.
Below is a simple example of how to load an AFF file and read its metadata:
using AFFKit.Core.Data.Chart;
using AFFKit.Core.Enumerators;
using var fs = new FileStream(@"E:\Arcaea Fanmade\Misaka Castle Fanmade Charts\ろん cover since 石風呂 with 初音ミク - ゆるふわ樹海ガール\4.aff", FileMode.Open, FileAccess.Read);
using var reader = new ArcChartReader(fs);
reader.ParseChart(AFFEventSortType.ByType);
var chart = reader.ToChart();
// fs and reader can be disposed safely since here
Console.WriteLine($"AudioOffset: {chart.AudioOffset}");
Console.WriteLine($"Timing Point Density Factor (TPDF): {chart.TimingPointDensityFactor}");
Console.WriteLine($"Number of Timing Groups (including default group): {chart.Groups.Count}");
Console.WriteLine($"Number of Notes (each long note counts as one): {chart.Groups.Sum(g => g.Events.Count(e => e is AFFNote))}");
Console.WriteLine($"Number of Judgable Notes (each long note counts as one): {chart.Groups.Where(g => !g.Params.Contains("noinput")).Sum(g => g.Events.Count(e => e is AFFNote))}");We welcome contributions! Feel free to open issues or submit pull requests.
Licensed under 123 Open-Source Organization MIT Public License 2.0. See LICENSE for more details.
Last Update: Jan 6th, 2026
