feat: Add CSV output format support

src/NuGetLicense/CommandLineOptionsParser.cs

@@ -138,6 +138,7 @@ public IOutputFormatter GetOutputFormatter(OutputType outputType, bool returnErr
                 OutputType.JsonPretty => new Output.Json.JsonOutputFormatter(true, returnErrorsOnly, !includeIgnoredPackages),
                 OutputType.Table => new Output.Table.TableOutputFormatter(returnErrorsOnly, !includeIgnoredPackages),
                 OutputType.Markdown => new Output.Table.TableOutputFormatter(returnErrorsOnly, !includeIgnoredPackages, printMarkdown: true),
+                OutputType.Csv => new Output.Csv.CsvOutputFormatter(returnErrorsOnly, !includeIgnoredPackages),
                 _ => throw new ArgumentOutOfRangeException($"{outputType} not supported")
             };
         }

src/NuGetLicense/Output/Csv/CsvOutputFormatter.cs

@@ -0,0 +1,90 @@
+// Licensed to the projects contributors.
+// The license conditions are provided in the LICENSE file located in the project root
+
+using System.Globalization;
+using NuGetLicense.LicenseValidator;
+
+namespace NuGetLicense.Output.Csv
+{
+    /// <summary>
+    /// Outputs license validation results in CSV format.
+    /// </summary>
+    public class CsvOutputFormatter : IOutputFormatter
+    {
+        private readonly bool _printErrorsOnly;
+        private readonly bool _skipIgnoredPackages;
+
+        public CsvOutputFormatter(bool printErrorsOnly, bool skipIgnoredPackages)
+        {
+            _printErrorsOnly = printErrorsOnly;
+            _skipIgnoredPackages = skipIgnoredPackages;
+        }
+
+        public async Task Write(Stream stream, IList<LicenseValidationResult> results)
+        {
+            if (_printErrorsOnly)
+            {
+                results = results.Where(r => r.ValidationErrors.Any()).ToList();
+            }
+            else if (_skipIgnoredPackages)
+            {
+                results = results.Where(r => r.LicenseInformationOrigin != LicenseInformationOrigin.Ignored).ToList();
+            }
+
+            using var writer = new StreamWriter(stream, leaveOpen: true);
+
+            // Write header
+            await writer.WriteLineAsync("Package,Version,License Information Origin,License Expression,License Url,Copyright,Authors,Description,Summary,Error,Error Context");
+
+            // Write rows
+            foreach (var result in results)
+            {
+                string errors = result.ValidationErrors.Any() 
+                    ? string.Join("; ", result.ValidationErrors.Select(e => EscapeCsvField(e.Error))) 
+                    : "";
+                string errorContexts = result.ValidationErrors.Any() 
+                    ? string.Join("; ", result.ValidationErrors.Select(e => EscapeCsvField(e.Context))) 
+                    : "";
+
+                var line = string.Join(",",
+                    EscapeCsvField(result.PackageId),
+                    EscapeCsvField(result.PackageVersion.ToString()),
+                    EscapeCsvField(result.LicenseInformationOrigin.ToString()),
+                    EscapeCsvField(result.License),
+                    EscapeCsvField(result.LicenseUrl),
+                    EscapeCsvField(result.Copyright),
+                    EscapeCsvField(result.Authors),
+                    EscapeCsvField(result.Description),
+                    EscapeCsvField(result.Summary),
+                    EscapeCsvField(errors),
+                    EscapeCsvField(errorContexts)
+                );
+
+                await writer.WriteLineAsync(line);
+            }
+
+            await writer.FlushAsync();
+        }
+
+        /// <summary>
+        /// Escapes a field for CSV output.
+        /// Handles fields containing commas, quotes, or newlines.
+        /// </summary>
+        private static string EscapeCsvField(string? field)
+        {
+            if (string.IsNullOrEmpty(field))
+            {
+                return "";
+            }
+
+            // If the field contains comma, quote, or newline, wrap it in quotes
+            if (field.Contains(',') || field.Contains('"') || field.Contains('\n') || field.Contains('\r'))
+            {
+                // Replace double quotes with two double quotes
+                return "\"" + field.Replace("\"", "\"\"") + "\"";
+            }
+
+            return field;
+        }
+    }
+}

src/NuGetLicense/Program.cs

@@ -41,7 +41,7 @@ public class Program : ICommandLineOptions
         [Option("-d|--license-information-download-location", Description = "Specifies a folder where the application will download all licenses provided via license URLs.")]
         public string? DownloadLicenseInformation { get; set; }
 
-        [Option("-o|--output", Description = "Specifies the output format. Valid values are Table, Markdown, Json, or JsonPretty (default: Table).")]
+        [Option("-o|--output", Description = "Specifies the output format. Valid values are Table, Markdown, Json, JsonPretty, or Csv (default: Table).")]
         public OutputType OutputType { get; set; } = OutputType.Table;
 
         [Option("-err|--error-only", Description = "When set, only validation errors are returned as result. Otherwise, all validation results are always returned.")]

src/NuGetUtility/OutputType.cs

@@ -1,4 +1,4 @@
-// Licensed to the projects contributors.
+// Licensed to the projects contributors.
 // The license conditions are provided in the LICENSE file located in the project root
 
 namespace NuGetUtility
@@ -8,6 +8,7 @@ public enum OutputType
         Table,
         Json,
         JsonPretty,
-        Markdown
+        Markdown,
+        Csv
     }
 }