diff --git a/CHANGELOG.md b/CHANGELOG.md
index 34164066..82cb3e45 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@ Latest
 ------
 
 ## Changes
+* [#312](https://github.com/cleverage/process-bundle/issues/312) Add read-only interfaces for the process manager and the registries, implemented by the existing classes and autowired by their interface: `ProcessManagerInterface` (`execute()`), `ProcessConfigurationRegistryInterface` (`getProcessConfiguration()`, `getProcessConfigurations()`, `hasProcessConfiguration()`), `TransformerRegistryInterface` (`getTransformer()`, `getTransformers()`, `hasTransformer()`) and `TaskRegistryInterface` (`getTask()`). Type your services on them: the classes will be `final` in v6.0 (the services of the bundle will then be typed on the interfaces). Update documentation, add tests.
 * [#310](https://github.com/cleverage/process-bundle/issues/310) Process configuration tree: a task `error_strategy` other than `skip` or `stop` is deprecated (notice when the container is compiled; it was accepted and the process failed with "Unknown error strategy" when the task failed), it will be rejected in v6.0. The process `public` key is a boolean node: a non-boolean value is rejected when the container is compiled, instead of a `TypeError` when the configuration is built. Describe the nodes of the process, task and generic transformer configurations (`config:dump-reference clever_age_process`). Update documentation, add tests.
 * [#309](https://github.com/cleverage/process-bundle/issues/309) Composer: `ext-intl` is no longer required, it is suggested: it is only needed by the `slugify` transformer (`SlugifyTransformer`), which is replaced by a service failing with an explicit message when the extension is missing (`UnavailableServicesCompilerPass`). Update documentation, add tests.
 * [#305](https://github.com/cleverage/process-bundle/issues/305) Bundle best practices, residues: the generic transformers are no longer autowired (explicit arguments). `ProcessHelpCommand` receives the `TaskRegistry` instead of the service container (passing a container is deprecated). Fetching from the service container a task of the application made public by the `TaskInterface` autoconfiguration is deprecated (`container.private` tag, new internal `PublicTaskDeprecationCompilerPass`); the tasks made public by the application itself are not concerned. Trigger the missing deprecation notices: `CheckSerializerCompilerPass`, `errors` task configuration key (use `error_outputs`). `TaskConfiguration::getErrors()` triggers a single notice on PHP 8.4+. `CleverAgeProcessBundle` is marked `@final since 5.4`. Update documentation, add tests.
diff --git a/config/services/manager.yaml b/config/services/manager.yaml
index a1fe6cfd..c11d9fd7 100644
--- a/config/services/manager.yaml
+++ b/config/services/manager.yaml
@@ -16,6 +16,8 @@ services:
 
     CleverAge\ProcessBundle\Manager\ProcessManager:
         alias: cleverage_process.manager.process
+    CleverAge\ProcessBundle\Manager\ProcessManagerInterface:
+        alias: cleverage_process.manager.process
 
     cleverage_process.context.contextual_option_resolver:
         class: CleverAge\ProcessBundle\Context\ContextualOptionResolver
diff --git a/config/services/registry.yaml b/config/services/registry.yaml
index 0db42234..73c10514 100644
--- a/config/services/registry.yaml
+++ b/config/services/registry.yaml
@@ -8,6 +8,8 @@ services:
             - ~
     CleverAge\ProcessBundle\Registry\ProcessConfigurationRegistry:
         alias: cleverage_process.registry.process_configuration
+    CleverAge\ProcessBundle\Registry\ProcessConfigurationRegistryInterface:
+        alias: cleverage_process.registry.process_configuration
 
     cleverage_process.registry.transformer:
         class: CleverAge\ProcessBundle\Registry\TransformerRegistry
@@ -16,6 +18,8 @@ services:
             - ~ # Service locator of the transformers by code, see TransformerLocatorCompilerPass
     CleverAge\ProcessBundle\Registry\TransformerRegistry:
         alias: cleverage_process.registry.transformer
+    CleverAge\ProcessBundle\Registry\TransformerRegistryInterface:
+        alias: cleverage_process.registry.transformer
 
     cleverage_process.registry.task:
         class: CleverAge\ProcessBundle\Registry\TaskRegistry
@@ -25,3 +29,5 @@ services:
             - '@service_container' # Deprecated fallback, removed in v6.0
     CleverAge\ProcessBundle\Registry\TaskRegistry:
         alias: cleverage_process.registry.task
+    CleverAge\ProcessBundle\Registry\TaskRegistryInterface:
+        alias: cleverage_process.registry.task
diff --git a/docs/04-advanced_workflow.md b/docs/04-advanced_workflow.md
index 0dac8136..2e6720c8 100644
--- a/docs/04-advanced_workflow.md
+++ b/docs/04-advanced_workflow.md
@@ -29,8 +29,11 @@ the process code, the task code and the original message. The original exception
 
 ### Executing a process from PHP
 
-The process manager service (`cleverage_process.manager.process`, private) can be autowired by its class,
-`CleverAge\ProcessBundle\Manager\ProcessManager`, or injected explicitly:
+The process manager service (`cleverage_process.manager.process`, private) can be autowired by its interface,
+`CleverAge\ProcessBundle\Manager\ProcessManagerInterface` (or by its class, `ProcessManager`), or injected
+explicitly. Type your services on the interface: the class will be `final` in v6.0 (the services of the bundle will
+then be typed on the interfaces, so that they can be decorated). The registries have their interface too: `ProcessConfigurationRegistryInterface`,
+`TransformerRegistryInterface` and `TaskRegistryInterface` (namespace `CleverAge\ProcessBundle\Registry`).
 
 ```yaml
 # config/services.yaml
diff --git a/src/Manager/ProcessManager.php b/src/Manager/ProcessManager.php
index ba9ce711..7e3bba10 100644
--- a/src/Manager/ProcessManager.php
+++ b/src/Manager/ProcessManager.php
@@ -42,7 +42,7 @@
  *
  * @final since 5.4
  */
-class ProcessManager implements ResetInterface
+class ProcessManager implements ProcessManagerInterface, ResetInterface
 {
     protected const EXECUTE_PROCESS = 1;
 
diff --git a/src/Manager/ProcessManagerInterface.php b/src/Manager/ProcessManagerInterface.php
new file mode 100644
index 00000000..234782a5
--- /dev/null
+++ b/src/Manager/ProcessManagerInterface.php
@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the CleverAge/ProcessBundle package.
+ *
+ * Copyright (c) Clever-Age
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace CleverAge\ProcessBundle\Manager;
+
+use CleverAge\ProcessBundle\Exception\MissingProcessException;
+use CleverAge\ProcessBundle\Exception\ProcessFailedException;
+
+/**
+ * Executes processes (implemented by ProcessManager, autowired by this interface).
+ */
+interface ProcessManagerInterface
+{
+    /**
+     * Executes the process with the given input (given to its entry point) and context, returns the last output of its
+     * end point (null without end point).
+     *
+     * @param array<string, mixed> $context
+     *
+     * @throws MissingProcessException when the process does not exist
+     * @throws ProcessFailedException  when a task fails with the "stop" error strategy
+     */
+    public function execute(string $processCode, mixed $input = null, array $context = []): mixed;
+}
diff --git a/src/Registry/ProcessConfigurationRegistry.php b/src/Registry/ProcessConfigurationRegistry.php
index 848cea51..915fa392 100644
--- a/src/Registry/ProcessConfigurationRegistry.php
+++ b/src/Registry/ProcessConfigurationRegistry.php
@@ -24,10 +24,10 @@
  *
  * @final since 5.4
  */
-class ProcessConfigurationRegistry
+class ProcessConfigurationRegistry implements ProcessConfigurationRegistryInterface
 {
     /**
-     * @var ProcessConfiguration[]
+     * @var array<string, ProcessConfiguration>
      */
     protected array $processConfigurations = [];
 
@@ -53,7 +53,7 @@ public function getProcessConfiguration(string $processCode): ProcessConfigurati
     }
 
     /**
-     * @return ProcessConfiguration[]
+     * @return array<string, ProcessConfiguration>
      */
     public function getProcessConfigurations(): array
     {
diff --git a/src/Registry/ProcessConfigurationRegistryInterface.php b/src/Registry/ProcessConfigurationRegistryInterface.php
new file mode 100644
index 00000000..d727d8cd
--- /dev/null
+++ b/src/Registry/ProcessConfigurationRegistryInterface.php
@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the CleverAge/ProcessBundle package.
+ *
+ * Copyright (c) Clever-Age
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace CleverAge\ProcessBundle\Registry;
+
+use CleverAge\ProcessBundle\Configuration\ProcessConfiguration;
+use CleverAge\ProcessBundle\Exception\InvalidProcessConfigurationException;
+use CleverAge\ProcessBundle\Exception\MissingProcessException;
+
+/**
+ * Gives the process configurations (implemented by ProcessConfigurationRegistry, autowired by this interface).
+ */
+interface ProcessConfigurationRegistryInterface
+{
+    /**
+     * @throws MissingProcessException              when the process does not exist
+     * @throws InvalidProcessConfigurationException when the process configuration is not valid
+     */
+    public function getProcessConfiguration(string $processCode): ProcessConfiguration;
+
+    /**
+     * @return array<string, ProcessConfiguration> indexed by process code
+     *
+     * @throws InvalidProcessConfigurationException when a process configuration is not valid
+     */
+    public function getProcessConfigurations(): array;
+
+    public function hasProcessConfiguration(string $processCode): bool;
+}
diff --git a/src/Registry/TaskRegistry.php b/src/Registry/TaskRegistry.php
index ba000ab3..dc04656d 100644
--- a/src/Registry/TaskRegistry.php
+++ b/src/Registry/TaskRegistry.php
@@ -24,7 +24,7 @@
  * (see TaskLocatorCompilerPass). The fallback container is only used, with a deprecation, for services that are not
  * in the locator (e.g. a process configuration added at runtime).
  */
-final class TaskRegistry
+final class TaskRegistry implements TaskRegistryInterface
 {
     public function __construct(
         protected ContainerInterface $locator,
diff --git a/src/Registry/TaskRegistryInterface.php b/src/Registry/TaskRegistryInterface.php
new file mode 100644
index 00000000..227758e7
--- /dev/null
+++ b/src/Registry/TaskRegistryInterface.php
@@ -0,0 +1,28 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the CleverAge/ProcessBundle package.
+ *
+ * Copyright (c) Clever-Age
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace CleverAge\ProcessBundle\Registry;
+
+use CleverAge\ProcessBundle\Configuration\TaskConfiguration;
+use CleverAge\ProcessBundle\Model\TaskInterface;
+
+/**
+ * Gives the task service of a task configuration (implemented by TaskRegistry, autowired by this interface).
+ */
+interface TaskRegistryInterface
+{
+    /**
+     * @throws \UnexpectedValueException when the service cannot be resolved or is not a TaskInterface
+     */
+    public function getTask(TaskConfiguration $taskConfiguration): TaskInterface;
+}
diff --git a/src/Registry/TransformerRegistry.php b/src/Registry/TransformerRegistry.php
index db4d5999..3614bab1 100644
--- a/src/Registry/TransformerRegistry.php
+++ b/src/Registry/TransformerRegistry.php
@@ -26,7 +26,7 @@
  *
  * @final since 5.4
  */
-class TransformerRegistry
+class TransformerRegistry implements TransformerRegistryInterface
 {
     /**
      * Transformers already fetched from the locator, and the ones registered with addTransformer() (deprecated).
diff --git a/src/Registry/TransformerRegistryInterface.php b/src/Registry/TransformerRegistryInterface.php
new file mode 100644
index 00000000..574ad390
--- /dev/null
+++ b/src/Registry/TransformerRegistryInterface.php
@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the CleverAge/ProcessBundle package.
+ *
+ * Copyright (c) Clever-Age
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace CleverAge\ProcessBundle\Registry;
+
+use CleverAge\ProcessBundle\Exception\MissingTransformerException;
+use CleverAge\ProcessBundle\Transformer\TransformerInterface;
+
+/**
+ * Gives the transformers by code (implemented by TransformerRegistry, autowired by this interface).
+ */
+interface TransformerRegistryInterface
+{
+    /**
+     * Instantiates every transformer.
+     *
+     * @return array<string, TransformerInterface> indexed by code
+     */
+    public function getTransformers(): array;
+
+    /**
+     * @throws MissingTransformerException when the transformer does not exist
+     */
+    public function getTransformer(string $code): TransformerInterface;
+
+    public function hasTransformer(string $code): bool;
+}
diff --git a/tests/DependencyInjection/CleverAgeProcessExtensionTest.php b/tests/DependencyInjection/CleverAgeProcessExtensionTest.php
index a0f5d545..b94004ec 100644
--- a/tests/DependencyInjection/CleverAgeProcessExtensionTest.php
+++ b/tests/DependencyInjection/CleverAgeProcessExtensionTest.php
@@ -19,9 +19,13 @@
 use CleverAge\ProcessBundle\DependencyInjection\CleverAgeProcessExtension;
 use CleverAge\ProcessBundle\DependencyInjection\Configuration;
 use CleverAge\ProcessBundle\Manager\ProcessManager;
+use CleverAge\ProcessBundle\Manager\ProcessManagerInterface;
 use CleverAge\ProcessBundle\Model\ProcessStopCheckerInterface;
 use CleverAge\ProcessBundle\Registry\ProcessConfigurationRegistry;
+use CleverAge\ProcessBundle\Registry\ProcessConfigurationRegistryInterface;
+use CleverAge\ProcessBundle\Registry\TaskRegistryInterface;
 use CleverAge\ProcessBundle\Registry\TransformerRegistry;
+use CleverAge\ProcessBundle\Registry\TransformerRegistryInterface;
 use CleverAge\ProcessBundle\Task\DummyTask;
 use CleverAge\ProcessBundle\Tests\Fixtures\AttributedTask;
 use CleverAge\ProcessBundle\Tests\Fixtures\AttributedTransformer;
@@ -91,6 +95,24 @@ public function testServicesCanBeAutowiredByClassName(): void
         }
     }
 
+    public function testServicesCanBeAutowiredByInterface(): void
+    {
+        $container = new ContainerBuilder();
+        (new CleverAgeProcessExtension())->load([], $container);
+
+        foreach ([
+            ProcessManagerInterface::class => 'cleverage_process.manager.process',
+            ProcessConfigurationRegistryInterface::class => 'cleverage_process.registry.process_configuration',
+            TransformerRegistryInterface::class => 'cleverage_process.registry.transformer',
+            TaskRegistryInterface::class => 'cleverage_process.registry.task',
+        ] as $interface => $id) {
+            self::assertSame($id, (string) $container->getAlias($interface));
+            $class = $container->getDefinition($id)->getClass();
+            self::assertIsString($class);
+            self::assertTrue(is_a($class, $interface, true), $class);
+        }
+    }
+
     public function testTasksAndTransformersAreAutoconfigured(): void
     {
         $container = new ContainerBuilder();