diff --git a/client/trailbase-dotnet/src/Client.cs b/client/trailbase-dotnet/src/Client.cs
index a9e9e28e..a794f11d 100644
--- a/client/trailbase-dotnet/src/Client.cs
+++ b/client/trailbase-dotnet/src/Client.cs
@@ -221,11 +221,11 @@ internal class ThinClient {
     }
 
     var query = (Dictionary<string, string> p) => {
-      var queryString = System.Web.HttpUtility.ParseQueryString(string.Empty);
-      foreach (var e in p) {
-        queryString.Add(e.Key, e.Value);
-      }
-      return queryString.ToString();
+      // NOTE: System.Web.HttpUtility encode '[' and ']' as "%5b" and "%5d", while we
+      // need the capital letter version. Use System.Net.WebUtility.UrlEncode instead.
+      var encode = System.Net.WebUtility.UrlEncode;
+      return string.Join("&",
+              p.Select(kvp => $"{encode(kvp.Key)}={encode(kvp.Value)}"));
     };
 
     var httpRequestMessage = new HttpRequestMessage {
diff --git a/client/trailbase-dotnet/src/RecordApi.cs b/client/trailbase-dotnet/src/RecordApi.cs
index 6930cac3..b4fd597f 100644
--- a/client/trailbase-dotnet/src/RecordApi.cs
+++ b/client/trailbase-dotnet/src/RecordApi.cs
@@ -206,6 +206,63 @@ public class ErrorEvent : Event {
 internal partial class SerializeResponseRecordIdContext : JsonSerializerContext {
 }
 
+/// <summary>Comparison operation for column filters, e.g. col != 'val'.</summary>
+public enum CompareOp {
+  /// <summary>Equal operator: '='.</summary>
+  Equal,
+  /// <summary>Not equal operator: '&lt;&gt;'.</summary>
+  NotEqual,
+  /// <summary>Less than operator: '&lt;'.</summary>
+  LessThan,
+  /// <summary>Less than equal operator: '&lt;='.</summary>
+  LessThanEqual,
+  /// <summary>Greater than operator: '&gt;'.</summary>
+  GreaterThan,
+  /// <summary>Greater than equal operator: '&gt;='.</summary>
+  GreaterThanEqual,
+  /// <summary>Like string operator: 'LIKE'.</summary>
+  Like,
+  /// <summary>Regular expression operator: 'REGEXP'.</summary>
+  Regexp,
+}
+
+/// <summary>Abstract base class for filters.</summary>
+public abstract class FilterBase { }
+
+/// <summary>Column filters.</summary>
+sealed public class Filter : FilterBase {
+  internal String column;
+  internal CompareOp? op;
+  internal String value;
+
+  /// <summary>Constructs column filter by column name, value and comparison operation</summary>
+  public Filter(String column, String value, CompareOp? op = null) {
+    this.column = column;
+    this.op = op;
+    this.value = value;
+  }
+}
+
+/// <summary>Logical "and" for column filters.</summary>
+sealed public class And : FilterBase {
+  internal List<FilterBase> filters;
+
+  /// <summary>Constructs logical "and".</summary>
+  public And(List<FilterBase> filters) {
+    this.filters = filters;
+  }
+}
+
+/// <summary>Logical "or" for column filters.</summary>
+sealed public class Or : FilterBase {
+  internal List<FilterBase> filters;
+
+  /// <summary>Constructs logical "or".</summary>
+  public Or(List<FilterBase> filters) {
+    this.filters = filters;
+  }
+}
+
 /// <summary>Main API to interact with Records.</summary>
 public class RecordApi {
   static readonly string _recordApi = "api/records/v1";
@@ -330,7 +387,7 @@ public class RecordApi {
   public async Task<ListResponse<T>> List<T>(
     Pagination? pagination = null,
     List<string>? order = null,
-    List<string>? filters = null,
+    List<FilterBase>? filters = null,
     List<string>? expand = null,
     bool count = false
   ) {
@@ -351,7 +408,7 @@ public class RecordApi {
     JsonTypeInfo<ListResponse<T>> jsonTypeInfo,
     Pagination? pagination = null,
     List<string>? order = null,
-    List<string>? filters = null,
+    List<FilterBase>? filters = null,
     List<string>? expand = null,
     bool count = false
   ) {
@@ -370,7 +427,7 @@ public class RecordApi {
   public async Task<ListResponse<JsonObject>> List(
     Pagination? pagination = null,
     List<string>? order = null,
-    List<string>? filters = null,
+    List<FilterBase>? filters = null,
     List<string>? expand = null,
     bool count = false
   ) {
@@ -382,7 +439,7 @@ public class RecordApi {
   private async Task<HttpContent> ListImpl(
     Pagination? pagination,
     List<string>? order,
-    List<string>? filters,
+    List<FilterBase>? filters,
     List<string>? expand,
     bool count
   ) {
@@ -416,18 +473,52 @@ public class RecordApi {
       param.Add("expand", String.Join(",", expand.ToArray()));
     }
 
-    if (filters != null) {
-      foreach (var filter in filters) {
-        var split = filter.Split('=', 2);
-        if (split.Length < 2) {
-          throw new Exception($"Filter '{filter}' does not match: 'name[op]=value'");
-        }
-        var nameOp = split[0];
-        var value = split[1];
-        param.Add(nameOp, value);
+    String op(CompareOp op) {
+      return op switch {
+        CompareOp.Equal => "$eq",
+        CompareOp.NotEqual => "$eq",
+        CompareOp.LessThan => "$lt",
+        CompareOp.LessThanEqual => "$lte",
+        CompareOp.GreaterThan => "$gt",
+        CompareOp.GreaterThanEqual => "$gte",
+        CompareOp.Like => "$like",
+        CompareOp.Regexp => "$re",
+        _ => "??",
+      };
+    }
+
+    void traverseFilters(String path, FilterBase filter) {
+      switch (filter) {
+        case Filter f:
+          if (f.op != null) {
+            var o = op((CompareOp)f.op);
+            param.Add($"{path}[{f.column}][{o}]", f.value);
+          }
+          else {
+            param.Add($"{path}[{f.column}]", f.value);
+          }
+          break;
+        case And f:
+          var i = 0;
+          foreach (var fil in f.filters) {
+            traverseFilters($"{path}[$and][{i++}]", fil);
+          }
+          break;
+        case Or f:
+          var j = 0;
+          foreach (var fil in f.filters) {
+            traverseFilters($"{path}[$or][{j++}]", fil);
+          }
+          break;
+        default:
+          break;
       }
     }
 
+    foreach (var filter in filters ?? []) {
+      traverseFilters("filter", filter);
+    }
+
     var response = await client.Fetch(
       $"{RecordApi._recordApi}/{name}",
       HttpMethod.Get,
diff --git a/client/trailbase-dotnet/test/ClientTest.cs b/client/trailbase-dotnet/test/ClientTest.cs
index e03884cc..5adf2817 100644
--- a/client/trailbase-dotnet/test/ClientTest.cs
+++ b/client/trailbase-dotnet/test/ClientTest.cs
@@ -163,11 +163,13 @@ public class ClientTest : IClassFixture<ClientTestFixture> {
       ListResponse<SimpleStrict> response = await api.List<SimpleStrict>(
         null,
         null,
-        [$"text_not_null={messages[0]}"],
+        [new Filter(column: "text_not_null", value: $"{messages[0]}")],
         null,
         false
       )!;
+      Console.WriteLine("FFFFIIII");
       Assert.Single(response.records);
+      Console.WriteLine("FFFFIIII AFTER");
       Assert.Null(response.total_count);
       Assert.Equal(messages[0], response.records[0].text_not_null);
     }
@@ -175,7 +177,7 @@ public class ClientTest : IClassFixture<ClientTestFixture> {
     {
       var responseAsc = await api.List<SimpleStrict>(
         order: ["+text_not_null"],
-        filters: [$"text_not_null[like]=% =?&{suffix}"],
+        filters: [new Filter(column: "text_not_null", value: $"% =?&{suffix}", op: CompareOp.Like)],
         count: true
       )!;
       Assert.Equal(2, responseAsc.total_count);
@@ -184,7 +186,7 @@ public class ClientTest : IClassFixture<ClientTestFixture> {
 
       var responseDesc = await api.List<SimpleStrict>(
         order: ["-text_not_null"],
-        filters: [$"text_not_null[like]=%{suffix}"]
+        filters: [new Filter("text_not_null", $"%{suffix}", op: CompareOp.Like)]
       )!;
       var recordsDesc = responseDesc.records;
       Assert.Equal(messages.Count, recordsDesc.Count);
@@ -217,7 +219,7 @@ public class ClientTest : IClassFixture<ClientTestFixture> {
       var id = ids[0];
       await api.Delete(id);
 
-      var response = await api.List<SimpleStrict>(filters: [$"text_not_null[like]=%{suffix}"])!;
+      var response = await api.List<SimpleStrict>(filters: [new Filter("text_not_null", $"%{suffix}", op: CompareOp.Like)])!;
 
       Assert.Single(response.records);
     }
@@ -249,7 +251,7 @@ public class ClientTest : IClassFixture<ClientTestFixture> {
     {
       ListResponse<SimpleStrict> response = await api.List(
         SerializeSimpleStrictContext.Default.ListResponseSimpleStrict,
-        filters: [$"text_not_null={messages[0]}"]
+        filters: [new Filter("text_not_null", $"{messages[0]}")]
       )!;
       Assert.Single(response.records);
       Assert.Equal(messages[0], response.records[0].text_not_null);
@@ -259,7 +261,7 @@ public class ClientTest : IClassFixture<ClientTestFixture> {
       var responseAsc = await api.List(
         SerializeSimpleStrictContext.Default.ListResponseSimpleStrict,
         order: ["+text_not_null"],
-        filters: [$"text_not_null[like]=% =?&{suffix}"]
+        filters: [new Filter("text_not_null", $"% =?&{suffix}", op: CompareOp.Like)]
       )!;
       var recordsAsc = responseAsc.records;
       Assert.Equal(messages.Count, recordsAsc.Count);
@@ -268,7 +270,7 @@ public class ClientTest : IClassFixture<ClientTestFixture> {
       var responseDesc = await api.List(
         SerializeSimpleStrictContext.Default.ListResponseSimpleStrict,
         order: ["-text_not_null"],
-        filters: [$"text_not_null[like]=%{suffix}"]
+        filters: [new Filter("text_not_null", $"%{suffix}", op: CompareOp.Like)]
       )!;
       var recordsDesc = responseDesc.records;
       Assert.Equal(messages.Count, recordsDesc.Count);
@@ -307,7 +309,7 @@ public class ClientTest : IClassFixture<ClientTestFixture> {
 
       var response = await api.List(
         SerializeSimpleStrictContext.Default.ListResponseSimpleStrict,
-        filters: [$"text_not_null[like]=%{suffix}"]
+        filters: [new Filter("text_not_null", $"%{suffix}", op: CompareOp.Like)]
       )!;
 
       Assert.Single(response.records);