diff --git a/pgLabII.PgUtils.Tests/ConnectionStrings/ConnectionStringServiceTests.cs b/pgLabII.PgUtils.Tests/ConnectionStrings/ConnectionStringServiceTests.cs
new file mode 100644
index 0000000..4342c08
--- /dev/null
+++ b/pgLabII.PgUtils.Tests/ConnectionStrings/ConnectionStringServiceTests.cs
@@ -0,0 +1,73 @@
+using pgLabII.PgUtils.ConnectionStrings;
+
+namespace pgLabII.PgUtils.Tests.ConnectionStrings;
+
+public class ConnectionStringServiceTests
+{
+    private readonly ConnectionStringService svc = ConnectionStringService.CreateDefault();
+
+    [Fact]
+    public void DetectFormat_Url()
+    {
+        var r = svc.DetectFormat("postgresql://user@localhost/db");
+        Assert.True(r.IsSuccess);
+        Assert.Equal(ConnStringFormat.Url, r.Value);
+    }
+
+    [Fact]
+    public void DetectFormat_Npgsql()
+    {
+        var r = svc.DetectFormat("Host=localhost;Database=db;Username=u");
+        Assert.True(r.IsSuccess);
+        Assert.Equal(ConnStringFormat.Npgsql, r.Value);
+    }
+
+    [Fact]
+    public void DetectFormat_Libpq()
+    {
+        var r = svc.DetectFormat("host=localhost dbname=db user=u");
+        Assert.True(r.IsSuccess);
+        Assert.Equal(ConnStringFormat.Libpq, r.Value);
+    }
+
+    [Fact]
+    public void ParseToDescriptor_DispatchesByFormat()
+    {
+        var r1 = svc.ParseToDescriptor("host=localhost dbname=db user=u");
+        Assert.True(r1.IsSuccess);
+        var r2 = svc.ParseToDescriptor("Host=localhost;Database=db;Username=u");
+        Assert.True(r2.IsSuccess);
+        var r3 = svc.ParseToDescriptor("postgresql://u@localhost/db");
+        Assert.True(r3.IsSuccess);
+    }
+
+    [Fact]
+    public void Convert_Libpq_to_Npgsql()
+    {
+        var input = "host=localhost port=5433 dbname=mydb user=alice password=secret sslmode=require";
+        var r = svc.Convert(input, ConnStringFormat.Npgsql);
+        Assert.True(r.IsSuccess);
+        var s = r.Value;
+        Assert.Contains("Host=localhost", s);
+        Assert.Contains("Port=5433", s);
+        Assert.Contains("Database=mydb", s);
+        Assert.Contains("Username=alice", s);
+        Assert.Contains("Password=secret", s);
+        Assert.Contains("SSL Mode=Require", s);
+    }
+
+    [Fact]
+    public void Convert_Url_to_Libpq()
+    {
+        var input = "postgresql://bob:pwd@host1:5432,host2:5433/db?application_name=cli&sslmode=prefer";
+        var r = svc.Convert(input, ConnStringFormat.Libpq);
+        Assert.True(r.IsSuccess);
+        var s = r.Value;
+        Assert.Contains("host=host1,host2", s);
+        // Ports differ (5432 vs 5433), libpq formatter emits a single port only when all ports are the same
+        Assert.DoesNotContain("port=", s);
+        Assert.Contains("dbname=db", s);
+        Assert.Contains("user=bob", s);
+        Assert.Contains("sslmode=prefer", s);
+    }
+}
diff --git a/pgLabII.PgUtils/ConnectionStrings/ConnectionStringService.cs b/pgLabII.PgUtils/ConnectionStrings/ConnectionStringService.cs
new file mode 100644
index 0000000..11e69b3
--- /dev/null
+++ b/pgLabII.PgUtils/ConnectionStrings/ConnectionStringService.cs
@@ -0,0 +1,90 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using FluentResults;
+
+namespace pgLabII.PgUtils.ConnectionStrings;
+
+/// <summary>
+/// Composite implementation that composes multiple codecs to detect, parse, format and convert
+/// PostgreSQL connection strings between formats.
+/// </summary>
+public sealed class ConnectionStringService : IConnectionStringService
+{
+    private readonly Dictionary<ConnStringFormat, IConnectionStringCodec> _codecs;
+    private readonly IConnectionStringCodec[] _all;
+
+    public ConnectionStringService(IEnumerable<IConnectionStringCodec> codecs)
+    {
+        _all = codecs?.ToArray() ?? Array.Empty<IConnectionStringCodec>();
+        _codecs = _all.GroupBy(c => c.Format).ToDictionary(g => g.Key, g => g.First());
+    }
+
+    /// <summary>
+    /// Creates a service pre-configured with built-in codecs (Libpq, Npgsql, Url).
+    /// </summary>
+    public static ConnectionStringService CreateDefault()
+        => new(new IConnectionStringCodec[] { new LibpqCodec(), new NpgsqlCodec(), new UrlCodec() });
+
+    public Result<ConnStringFormat> DetectFormat(string input)
+    {
+        if (string.IsNullOrWhiteSpace(input))
+            return Result.Fail<ConnStringFormat>("Empty input");
+
+        // URL: postgresql:// or postgres://
+        var trimmed = input.TrimStart();
+        if (trimmed.StartsWith("postgresql://", StringComparison.OrdinalIgnoreCase) ||
+            trimmed.StartsWith("postgres://", StringComparison.OrdinalIgnoreCase))
+        {
+            return Result.Ok(ConnStringFormat.Url);
+        }
+
+        // Heuristic for Npgsql: presence of ';' separator and typical keys like Host= or Username=
+        // Also many .NET conn strings end with a trailing semicolon but not required.
+        if (trimmed.Contains(';'))
+        {
+            var firstEq = trimmed.IndexOf('=');
+            var firstSemi = trimmed.IndexOf(';');
+            if (firstEq > 0 && (firstSemi > firstEq || firstSemi == -1))
+            {
+                // quick key sample
+                var key = trimmed.Substring(0, firstEq).Trim();
+                if (key.Length > 0)
+                    return Result.Ok(ConnStringFormat.Npgsql);
+            }
+        }
+
+        // Fallback to libpq if it looks like space-separated key=value or single pair
+        // Very loose heuristic: contains '=' and either a space-separated sequence or quotes
+        if (trimmed.Contains('='))
+        {
+            return Result.Ok(ConnStringFormat.Libpq);
+        }
+
+        return Result.Fail<ConnStringFormat>("Unable to detect format");
+    }
+
+    public Result<ConnectionDescriptor> ParseToDescriptor(string input)
+    {
+        var fmtRes = DetectFormat(input);
+        if (fmtRes.IsFailed) return Result.Fail<ConnectionDescriptor>(fmtRes.Errors);
+        var fmt = fmtRes.Value;
+        if (!_codecs.TryGetValue(fmt, out var codec))
+            return Result.Fail<ConnectionDescriptor>($"No codec registered for {fmt}");
+        return codec.TryParse(input);
+    }
+
+    public Result<string> FormatFromDescriptor(ConnectionDescriptor descriptor, ConnStringFormat targetFormat)
+    {
+        if (!_codecs.TryGetValue(targetFormat, out var codec))
+            return Result.Fail<string>($"No codec registered for {targetFormat}");
+        return codec.TryFormat(descriptor);
+    }
+
+    public Result<string> Convert(string input, ConnStringFormat targetFormat)
+    {
+        var parseRes = ParseToDescriptor(input);
+        if (parseRes.IsFailed) return Result.Fail<string>(parseRes.Errors);
+        return FormatFromDescriptor(parseRes.Value, targetFormat);
+    }
+}