diff --git a/README.md b/README.md
index c25870f..a8c92ef 100644
--- a/README.md
+++ b/README.md
@@ -18,7 +18,7 @@ A Symfony 8+ bundle for Bootstrap-first business datatables driven by PHP defini
 - **Twig Rendering**: Render tables with a single Twig function: `{{ zhortein_datatable() }}`.
 - **Ajax Fragments**: Seamless server-side updates using vanilla Stimulus.
 - **Data Providers**: Native support for **Doctrine ORM** and **Array** providers.
-- **Filtering**: Built-in global search and permanent backend filters.
+- **Filtering**: Built-in global search, toolbar/header filters, and advanced **Search Builder**.
 - **Actions**: Declarative row and global actions with CSRF-aware non-GET support.
 - **Exports**: Server-side CSV and optional XLSX exports.
 - **Customization**: Flexible UI/UX customization via Twig blocks and themes.
@@ -91,6 +91,7 @@ final class UserDatatable implements DatatableInterface
 - [Providers Overview](docs/providers.md)
 - [Doctrine Provider](docs/doctrine-provider.md)
 - [Filters](docs/filters.md)
+- [Advanced Filters](docs/advanced-filters.md)
 - [Actions & Security](docs/actions.md)
 - [Bulk Actions & Selection](docs/bulk-actions.md)
 - [Exports](docs/exports.md)
diff --git a/docs/advanced-filters.md b/docs/advanced-filters.md
new file mode 100644
index 0000000..e5fc21a
--- /dev/null
+++ b/docs/advanced-filters.md
@@ -0,0 +1,135 @@
+# Advanced Filter Expressions
+
+The "Advanced Filter Expressions" system (also referred to as **Search Builder**) allows users to build complex, nested filtering logic using `AND`/`OR` groups and various operators.
+
+## Enabling Advanced Filters
+
+Advanced filters are disabled by default. You can enable them globally or per-datatable.
+
+### Global Enablement
+
+In your `zhortein_datatable.yaml` configuration:
+
+```yaml
+zhortein_datatable:
+    search_builder_enabled: true
+```
+
+### Per-Datatable Enablement
+
+When rendering the datatable in Twig:
+
+```twig
+{{ zhortein_datatable('users', {
+    searchBuilder: true
+}) }}
+```
+
+## Declaring Filterable Fields
+
+Unlike simple filters, fields for the Search Builder must be explicitly declared in your `DatatableDefinition` using `addAdvancedFilterField()`. This ensures a strict security boundary where only intended fields are exposed to the frontend.
+
+```php
+use Zhortein\DatatableBundle\Enum\FilterType;
+use Zhortein\DatatableBundle\Enum\FilterOperator;
+
+$definition->addAdvancedFilterField(
+    name: 'email',
+    field: 'e.email',
+    label: 'Email',
+    type: FilterType::Text,
+    allowedOperators: [
+        FilterOperator::Equals,
+        FilterOperator::Contains,
+        FilterOperator::StartsWith,
+    ]
+);
+```
+
+### Options
+
+| Option | Description |
+|---|---|
+| `name` | Public field name used in the frontend payload. |
+| `field` | Provider field targeted (e.g., `e.email` or `organization.name`). |
+| `label` | (Optional) Human-readable label rendered in the UI. Defaults to a capitalized version of `name`. |
+| `type` | `FilterType` enum value (Text, Choice, Boolean, Date, Number). |
+| `allowedOperators` | (Optional) List of `FilterOperator` allowed for this field. If empty, all operators compatible with the type are allowed. |
+| `choices` | (Optional) Array of choices for `Choice` fields. |
+
+## Supported Types and Operators
+
+### Types
+
+The Search Builder supports the following types from the `FilterType` enum:
+- `Text`
+- `Choice`
+- `Boolean`
+- `Date`
+- `Number`
+
+### Operators
+
+The following operators are supported (see `ComparisonOperator` enum for internal values):
+
+| Label | Internal Code | Behavior |
+|---|---|---|
+| **Equals** | `eq` | Exact match. |
+| **Not Equals** | `neq` | Not equal match. |
+| **Contains** | `contains` | Case-insensitive `LIKE %value%`. |
+| **Does not contain** | `not_contains` | Case-insensitive `NOT LIKE %value%`. |
+| **Starts with** | `starts_with` | Case-insensitive `LIKE value%`. |
+| **Ends with** | `ends_with` | Case-insensitive `LIKE %value`. |
+| **Greater than** | `gt` | `>` comparison. |
+| **Greater than or equals** | `gte` | `>=` comparison. |
+| **Less than** | `lt` | `<` comparison. |
+| **Less than or equals** | `lte` | `<=` comparison. |
+| **Between** | `between` | `BETWEEN value1 AND value2`. |
+| **Is null** | `is_null` | `IS NULL` check. |
+| **Is not null** | `is_not_null` | `IS NOT NULL` check. |
+| **In** | `in` | `IN (value1, value2, ...)` check. |
+| **Not in** | `not_in` | `NOT IN (value1, value2, ...)` check. |
+
+## Logic and Nesting
+
+The Search Builder supports `AND` and `OR` logic. Users can create nested groups to build complex expressions:
+
+- **Root Group**: The top-level group (defaults to `AND`).
+- **Sub-groups**: Additional groups can be added inside other groups (up to a depth of 3).
+
+## Provider Behavior
+
+### Doctrine Provider
+
+Advanced filters are applied directly to the Doctrine `QueryBuilder`. 
+- **Join Handling**: Joins are automatically managed based on the field references (e.g., `organization.name` will use the `organization` alias).
+- **Case Sensitivity**: String comparisons (`Contains`, `Starts with`, etc.) use `LOWER()` on both the field and the parameter for database-agnostic case-insensitivity.
+- **Security**: All parameters are bound using Doctrine parameter binding to prevent SQL injection.
+
+### Array Provider
+
+Advanced filters work with the Array provider as well. The evaluator performs in-memory comparisons:
+- **Case Sensitivity**: String comparisons are performed using `mb_strtolower`.
+- **Date Handling**: Supports `\DateTimeInterface` objects and `Y-m-d` date strings.
+- **Type Coercion**: Performs basic type coercion (e.g., numeric strings vs numbers) to ensure consistent results.
+
+## Export Behavior
+
+When exporting to CSV or XLSX, the active advanced filters are automatically applied to the exported dataset, ensuring the export matches the user's current view.
+
+## Security Boundaries
+
+Security is a core design principle of the Advanced Filters system:
+
+1.  **Backend-defined Fields**: Only fields explicitly declared with `addAdvancedFilterField()` can be used in expressions. Attempting to filter on undeclared fields will result in the condition being ignored.
+2.  **No Arbitrary DQL/SQL**: The frontend sends a declarative JSON payload. The backend parses this payload into a structured expression tree. No raw DQL or SQL is ever accepted from the client.
+3.  **Strict Operators**: The backend validates that only supported operators are used.
+4.  **Parameter Binding**: All values from the frontend are treated as parameters and bound using Doctrine's secure parameter binding system. No values are ever directly concatenated into query strings.
+5.  **Depth Limit**: The expression tree depth is limited (default 3) to prevent complex query exhaustion attacks.
+
+## Limitations
+
+- **Saved Presets**: There is currently no support for saving or sharing filter presets.
+- **User Persistence**: Advanced filters are not persisted between sessions or page reloads.
+- **Third-party Widgets**: The current implementation uses standard Bootstrap inputs; custom widgets like Select2 or specialized datepickers are not yet supported.
+- **Collection-valued Associations**: Filtering on collection-valued associations (e.g., "Users having at least one Role with name X") is not supported.
diff --git a/docs/filters.md b/docs/filters.md
index 315f55f..142ef71 100644
--- a/docs/filters.md
+++ b/docs/filters.md
@@ -10,10 +10,10 @@ Currently implemented:
 -   **Types**: Text, Choice, Boolean, Date, Date Range, Number, Number Range.
 -   **Layouts**: Toolbar (default) and Column Header Dropdowns.
 -   **Features**: Active filter summary, clear filters action, Stimulus-powered refresh with debouncing.
+-   **Advanced Filters**: [Advanced search builder](advanced-filters.md) for complex `AND`/`OR` logic.
 
 Not implemented yet:
--   Advanced SearchBuilder-style expressions (only `AND` is supported).
--   Nested filter groups.
+-   Nested filter groups (simple filters only).
 -   Persisted filter presets.
 -   Custom filter widgets (Select2, datepickers).
 -   Collection-valued association filters.
diff --git a/docs/index.md b/docs/index.md
index 04c7682..5078a06 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -14,6 +14,7 @@ This bundle is a Symfony 8+ datatable bundle for Bootstrap-first business tables
 
 - [Providers](providers.md): Array and Doctrine data sources.
 - [Filters](filters.md): Toolbar and header-based data filtering.
+- [Advanced Filters](advanced-filters.md): Complex nested filtering with Search Builder.
 - [Actions and Security](actions.md): Row-level and global table actions with CSRF and authorization.
 - [Bulk Actions and Selection](bulk-actions.md): Managing multiple rows at once.
 - [UI/UX and Controls](ui-ux.md): Search, pagination, sorting, and UI customization.