diff --git a/README.md b/README.md
index 5b284fa..953110f 100644
--- a/README.md
+++ b/README.md
@@ -2,10 +2,18 @@
 
 # Kafka Schema Registry API Client
 
-## What is it?
+## Description
 An API Client written in PHP to communicate with Kafka Schema Registry.
 
-## What it can do?
+## Installation
+```bash
+composer require jobcloud/php-kafka-schema-registry-client
+```
+
+## Requirements
+- php: >= 7.4
+
+## Supported API calls
 Currently it supports:
 
 * Get list of subjects
@@ -24,13 +32,7 @@ Currently it supports:
 * Get Subject's latest schema version
 * Setting the registry mode
 
-## How to use it?
-### Installation
-```bash
-composer require jobcloud/php-kafka-schema-registry-client
-```
-
-### Code example
+## Code example
 
 ```php
 <?php
@@ -85,7 +87,7 @@ $api = $container['kafka.schema.registry.client.api']);
 $data = $api->getSubjects();
 ```
 
-## External links?
-If you want to be so kind to extend this library, make a pull request, 
-and whatever functionality you want to implement, this is a API reference to follow: 
+## Contributing
+This is an open source project that welcomes pull requests and issues from anyone.  
+This is the API reference to follow for any new functionality: 
 https://docs.confluent.io/current/schema-registry/develop/api.html
diff --git a/composer.json b/composer.json
index 1ee9277..b3fc3cd 100644
--- a/composer.json
+++ b/composer.json
@@ -19,7 +19,7 @@
         "sort-packages": true
     },
     "require": {
-        "php": ">7.3",
+        "php": ">=7.4",
         "ext-json": "*",
         "pimple/pimple": "^3.2",
         "symfony/cache": "^5.0",
@@ -29,9 +29,9 @@
     },
     "require-dev": {
         "squizlabs/php_codesniffer": "^3.4.2",
-        "phpunit/phpunit": "^8.3.4",
-        "phpstan/phpstan": "^0.11.8",
+        "phpunit/phpunit": "^9.5",
+        "phpstan/phpstan": "^0.12",
         "rregeer/phpunit-coverage-check": "^0.3.1",
-        "infection/infection": "^0.14.2"
+        "infection/infection": "^0.21"
     }
 }
diff --git a/docker/.env b/docker/.env
new file mode 100644
index 0000000..850bf32
--- /dev/null
+++ b/docker/.env
@@ -0,0 +1 @@
+COMPOSE_PROJECT_NAME=php-kafka-schema-registry-client
\ No newline at end of file
diff --git a/docker/dev/php/Dockerfile b/docker/dev/php/Dockerfile
index b4548f0..ea447d0 100644
--- a/docker/dev/php/Dockerfile
+++ b/docker/dev/php/Dockerfile
@@ -1,4 +1,4 @@
-FROM php:7.3-cli-alpine3.10
+FROM php:7.4-cli-alpine3.10
 
 ARG HOST_USER_ID
 
diff --git a/phpstan.neon b/phpstan.neon
index fff6e34..20b7cf9 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -1,4 +1,4 @@
 parameters:
   paths:
     - src
-  level: 7
+  level: 8
diff --git a/phpunit.xml b/phpunit.xml
index 7a254aa..478d6bf 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -1,46 +1,30 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit
-        backupGlobals               = "false"
-        backupStaticAttributes      = "false"
-        colors                      = "true"
-        convertErrorsToExceptions   = "true"
-        convertNoticesToExceptions  = "true"
-        convertWarningsToExceptions = "true"
-        processIsolation            = "false"
-        stopOnFailure               = "false"
-        bootstrap                   = "vendor/autoload.php" >
-    <php>
-        <ini name="max_execution_time" value="-1"/>
-        <ini name="html_errors" value="false"/>
-        <ini name="memory_limit" value="2G"/>
-
-        <ini name="xdebug.default_enable" value="1" />
-        <ini name="xdebug.enable_coverage" value="1" />
-        <ini name="xdebug.remote_autostart" value="0" />
-        <ini name="xdebug.remote_enable" value="0" />
-        <ini name="xdebug.overload_var_dump" value="0" />
-        <ini name="xdebug.show_mem_delta" value="0" />
-
-        <env name="ENVIRONMENT" value="test" />
-    </php>
-
-    <testsuites>
-        <testsuite name="Unit">
-            <directory>./tests</directory>
-        </testsuite>
-    </testsuites>
-
-    <filter>
-        <whitelist>
-            <directory>src</directory>
-        </whitelist>
-    </filter>
-
-    <logging>
-        <log type="coverage-text" target="php://stdout" showOnlySummary="true"/>
-        <log type="coverage-clover" target="build/logs/phpunit/coverage/coverage.xml"/>
-        <log type="coverage-html" target="build/logs/phpunit/coverage"/>
-        <log type="coverage-xml" target="build/logs/phpunit/coverage/coverage-xml"/>
-        <log type="junit" target="build/logs/phpunit/junit.xml"/>
-    </logging>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" backupGlobals="false" backupStaticAttributes="false" colors="true" convertErrorsToExceptions="true" convertNoticesToExceptions="true" convertWarningsToExceptions="true" processIsolation="false" stopOnFailure="false" bootstrap="vendor/autoload.php" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd">
+  <coverage>
+    <include>
+      <directory>src</directory>
+    </include>
+    <report>
+      <clover outputFile="build/logs/phpunit/coverage/coverage.xml"/>
+      <html outputDirectory="build/logs/phpunit/coverage"/>
+      <text outputFile="php://stdout" showOnlySummary="true"/>
+      <xml outputDirectory="build/logs/phpunit/coverage/coverage-xml"/>
+    </report>
+  </coverage>
+  <php>
+    <ini name="max_execution_time" value="-1"/>
+    <ini name="html_errors" value="false"/>
+    <ini name="memory_limit" value="2G"/>
+    <env name="error_reporting" value="E_ALL"/>
+    <env name="display_errors" value="1"/>
+    <env name="ENVIRONMENT" value="test"/>
+  </php>
+  <testsuites>
+    <testsuite name="Unit">
+      <directory>./tests</directory>
+    </testsuite>
+  </testsuites>
+  <logging>
+    <junit outputFile="build/logs/phpunit/junit.xml"/>
+  </logging>
 </phpunit>
diff --git a/src/ErrorHandler.php b/src/ErrorHandler.php
index e921b93..97e5332 100644
--- a/src/ErrorHandler.php
+++ b/src/ErrorHandler.php
@@ -2,9 +2,9 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient;
 
+use Buzz\Exception\ClientException;
 use Jobcloud\Kafka\SchemaRegistryClient\Exception\BackendDatastoreException;
 use Jobcloud\Kafka\SchemaRegistryClient\Exception\ImportException;
-use Jobcloud\Kafka\SchemaRegistryClient\Exception\ClientException;
 use Jobcloud\Kafka\SchemaRegistryClient\Exception\CompatibilityException;
 use Jobcloud\Kafka\SchemaRegistryClient\Exception\IncompatibileAvroSchemaException;
 use Jobcloud\Kafka\SchemaRegistryClient\Exception\InvalidAvroSchemaException;
@@ -13,12 +13,15 @@
 use Jobcloud\Kafka\SchemaRegistryClient\Exception\PathNotFoundException;
 use Jobcloud\Kafka\SchemaRegistryClient\Exception\RequestForwardException;
 use Jobcloud\Kafka\SchemaRegistryClient\Exception\SchemaNotFoundException;
+use Jobcloud\Kafka\SchemaRegistryClient\Exception\SchemaRegistryExceptionInterface;
 use Jobcloud\Kafka\SchemaRegistryClient\Exception\SubjectNotFoundException;
 use Jobcloud\Kafka\SchemaRegistryClient\Exception\UnauthorizedException;
 use Jobcloud\Kafka\SchemaRegistryClient\Exception\UnprocessableEntityException;
 use Jobcloud\Kafka\SchemaRegistryClient\Exception\VersionNotFoundException;
+use Psr\Http\Client\ClientExceptionInterface;
 use Psr\Http\Message\RequestInterface;
 use Psr\Http\Message\ResponseInterface;
+use JsonException;
 
 class ErrorHandler implements ErrorHandlerInterface
 {
@@ -42,6 +45,9 @@ class ErrorHandler implements ErrorHandlerInterface
      * @throws UnprocessableEntityException
      * @throws VersionNotFoundException
      * @throws ImportException
+     * @throws JsonException
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
      */
     public function handleError(ResponseInterface $response, string $uri = null, RequestInterface $request = null): void
     {
diff --git a/src/ErrorHandlerInterface.php b/src/ErrorHandlerInterface.php
index 2ec4e66..aca8580 100644
--- a/src/ErrorHandlerInterface.php
+++ b/src/ErrorHandlerInterface.php
@@ -2,14 +2,20 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient;
 
+use Jobcloud\Kafka\SchemaRegistryClient\Exception\SchemaRegistryExceptionInterface;
+use Psr\Http\Client\ClientExceptionInterface;
 use Psr\Http\Message\RequestInterface;
 use Psr\Http\Message\ResponseInterface;
+use JsonException;
 
 interface ErrorHandlerInterface
 {
     /**
      * @param ResponseInterface $response
      * @param string|null       $uri
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function handleError(
         ResponseInterface $response,
diff --git a/src/Exception/AbstractKafkaSchemaRegistryException.php b/src/Exception/AbstractKafkaSchemaRegistryException.php
new file mode 100644
index 0000000..58ba84b
--- /dev/null
+++ b/src/Exception/AbstractKafkaSchemaRegistryException.php
@@ -0,0 +1,10 @@
+<?php
+
+namespace Jobcloud\Kafka\SchemaRegistryClient\Exception;
+
+use Exception;
+
+abstract class AbstractKafkaSchemaRegistryException extends Exception implements SchemaRegistryExceptionInterface
+{
+
+}
diff --git a/src/Exception/BackendDatastoreException.php b/src/Exception/BackendDatastoreException.php
index 9a2fecf..e6464c8 100644
--- a/src/Exception/BackendDatastoreException.php
+++ b/src/Exception/BackendDatastoreException.php
@@ -2,9 +2,7 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient\Exception;
 
-use Exception;
-
-class BackendDatastoreException extends Exception
+class BackendDatastoreException extends AbstractKafkaSchemaRegistryException
 {
 
 }
diff --git a/src/Exception/ClientException.php b/src/Exception/ClientException.php
deleted file mode 100644
index 33f58c9..0000000
--- a/src/Exception/ClientException.php
+++ /dev/null
@@ -1,10 +0,0 @@
-<?php
-
-namespace Jobcloud\Kafka\SchemaRegistryClient\Exception;
-
-use Exception;
-
-class ClientException extends Exception
-{
-
-}
diff --git a/src/Exception/CompatibilityException.php b/src/Exception/CompatibilityException.php
index 24a321f..206491b 100644
--- a/src/Exception/CompatibilityException.php
+++ b/src/Exception/CompatibilityException.php
@@ -2,9 +2,7 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient\Exception;
 
-use Exception;
-
-class CompatibilityException extends Exception
+class CompatibilityException extends AbstractKafkaSchemaRegistryException
 {
 
 }
diff --git a/src/Exception/ImportException.php b/src/Exception/ImportException.php
index 06905cb..1bfbef9 100644
--- a/src/Exception/ImportException.php
+++ b/src/Exception/ImportException.php
@@ -2,9 +2,7 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient\Exception;
 
-use Exception;
-
-class ImportException extends Exception
+class ImportException extends AbstractKafkaSchemaRegistryException
 {
 
 }
diff --git a/src/Exception/IncompatibileAvroSchemaException.php b/src/Exception/IncompatibileAvroSchemaException.php
index 5bc577e..446e612 100644
--- a/src/Exception/IncompatibileAvroSchemaException.php
+++ b/src/Exception/IncompatibileAvroSchemaException.php
@@ -2,9 +2,7 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient\Exception;
 
-use Exception;
-
-class IncompatibileAvroSchemaException extends Exception
+class IncompatibileAvroSchemaException extends AbstractKafkaSchemaRegistryException
 {
 
 }
diff --git a/src/Exception/InvalidAvroSchemaException.php b/src/Exception/InvalidAvroSchemaException.php
index f361636..3fa453a 100644
--- a/src/Exception/InvalidAvroSchemaException.php
+++ b/src/Exception/InvalidAvroSchemaException.php
@@ -2,9 +2,7 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient\Exception;
 
-use Exception;
-
-class InvalidAvroSchemaException extends Exception
+class InvalidAvroSchemaException extends AbstractKafkaSchemaRegistryException
 {
 
 }
diff --git a/src/Exception/InvalidVersionException.php b/src/Exception/InvalidVersionException.php
index 4e8e189..6b9d5f5 100644
--- a/src/Exception/InvalidVersionException.php
+++ b/src/Exception/InvalidVersionException.php
@@ -2,9 +2,7 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient\Exception;
 
-use Exception;
-
-class InvalidVersionException extends Exception
+class InvalidVersionException extends AbstractKafkaSchemaRegistryException
 {
 
 }
diff --git a/src/Exception/OperationTimeoutException.php b/src/Exception/OperationTimeoutException.php
index aa4eb05..4fcbcad 100644
--- a/src/Exception/OperationTimeoutException.php
+++ b/src/Exception/OperationTimeoutException.php
@@ -2,9 +2,7 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient\Exception;
 
-use Exception;
-
-class OperationTimeoutException extends Exception
+class OperationTimeoutException extends AbstractKafkaSchemaRegistryException
 {
 
 }
diff --git a/src/Exception/PathNotFoundException.php b/src/Exception/PathNotFoundException.php
index 47d4045..9f75f54 100644
--- a/src/Exception/PathNotFoundException.php
+++ b/src/Exception/PathNotFoundException.php
@@ -2,9 +2,7 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient\Exception;
 
-use Exception;
-
-class PathNotFoundException extends Exception
+class PathNotFoundException extends AbstractKafkaSchemaRegistryException
 {
 
 }
diff --git a/src/Exception/RequestForwardException.php b/src/Exception/RequestForwardException.php
index 481ee7b..b81fe8b 100644
--- a/src/Exception/RequestForwardException.php
+++ b/src/Exception/RequestForwardException.php
@@ -2,9 +2,7 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient\Exception;
 
-use Exception;
-
-class RequestForwardException extends Exception
+class RequestForwardException extends AbstractKafkaSchemaRegistryException
 {
 
 }
diff --git a/src/Exception/SchemaNotFoundException.php b/src/Exception/SchemaNotFoundException.php
index 23f503a..7ca40b9 100644
--- a/src/Exception/SchemaNotFoundException.php
+++ b/src/Exception/SchemaNotFoundException.php
@@ -2,9 +2,7 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient\Exception;
 
-use Exception;
-
-class SchemaNotFoundException extends Exception
+class SchemaNotFoundException extends AbstractKafkaSchemaRegistryException
 {
 
 }
diff --git a/src/Exception/SchemaRegistryExceptionInterface.php b/src/Exception/SchemaRegistryExceptionInterface.php
new file mode 100644
index 0000000..844e282
--- /dev/null
+++ b/src/Exception/SchemaRegistryExceptionInterface.php
@@ -0,0 +1,10 @@
+<?php
+
+namespace Jobcloud\Kafka\SchemaRegistryClient\Exception;
+
+use Psr\Http\Client\ClientExceptionInterface;
+
+interface SchemaRegistryExceptionInterface extends ClientExceptionInterface
+{
+
+}
diff --git a/src/Exception/SubjectNotFoundException.php b/src/Exception/SubjectNotFoundException.php
index e7b443a..87c45dc 100644
--- a/src/Exception/SubjectNotFoundException.php
+++ b/src/Exception/SubjectNotFoundException.php
@@ -2,9 +2,7 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient\Exception;
 
-use Exception;
-
-class SubjectNotFoundException extends Exception
+class SubjectNotFoundException extends AbstractKafkaSchemaRegistryException
 {
 
 }
diff --git a/src/Exception/UnauthorizedException.php b/src/Exception/UnauthorizedException.php
index 45f976a..62e7cbd 100644
--- a/src/Exception/UnauthorizedException.php
+++ b/src/Exception/UnauthorizedException.php
@@ -2,9 +2,7 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient\Exception;
 
-use Exception;
-
-class UnauthorizedException extends Exception
+class UnauthorizedException extends AbstractKafkaSchemaRegistryException
 {
 
 }
diff --git a/src/Exception/UnprocessableEntityException.php b/src/Exception/UnprocessableEntityException.php
index bc04d88..498f561 100644
--- a/src/Exception/UnprocessableEntityException.php
+++ b/src/Exception/UnprocessableEntityException.php
@@ -2,9 +2,7 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient\Exception;
 
-use Exception;
-
-class UnprocessableEntityException extends Exception
+class UnprocessableEntityException extends AbstractKafkaSchemaRegistryException
 {
 
 }
diff --git a/src/Exception/VersionNotFoundException.php b/src/Exception/VersionNotFoundException.php
index 46c2463..4ec5638 100644
--- a/src/Exception/VersionNotFoundException.php
+++ b/src/Exception/VersionNotFoundException.php
@@ -2,9 +2,7 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient\Exception;
 
-use Exception;
-
-class VersionNotFoundException extends Exception
+class VersionNotFoundException extends AbstractKafkaSchemaRegistryException
 {
 
 }
diff --git a/src/HttpClient.php b/src/HttpClient.php
index 989d87f..6c9bf5e 100644
--- a/src/HttpClient.php
+++ b/src/HttpClient.php
@@ -2,10 +2,12 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient;
 
+use Jobcloud\Kafka\SchemaRegistryClient\Exception\SchemaRegistryExceptionInterface;
 use Psr\Http\Client\ClientExceptionInterface;
 use Psr\Http\Client\ClientInterface;
 use Psr\Http\Message\RequestFactoryInterface;
 use Psr\Http\Message\RequestInterface;
+use JsonException;
 
 class HttpClient implements HttpClientInterface
 {
@@ -66,9 +68,10 @@ public function __construct(
     /**
      * @param string $method
      * @param string $uri
-     * @param array $body
-     * @param array $queryParams
+     * @param array<string,mixed> $body
+     * @param array<string,mixed> $queryParams
      * @return RequestInterface
+     * @throws JsonException
      */
     private function createRequest(
         string $method,
@@ -86,9 +89,9 @@ private function createRequest(
         if ([] !== $body) {
             $jsonData = json_encode($body, JSON_THROW_ON_ERROR);
 
-            $dataLength = (string) strlen($jsonData);
+            $dataLength = strlen($jsonData);
 
-            $request = $request->withAddedHeader('Content-Length', $dataLength);
+            $request = $request->withAddedHeader('Content-Length', (string) $dataLength);
             $request->getBody()->write($jsonData);
         }
 
@@ -107,10 +110,12 @@ private function createRequest(
     /**
      * @param string $method
      * @param string $uri
-     * @param array $body
-     * @param array $queryParams
+     * @param array<string,mixed> $body
+     * @param array<string,mixed> $queryParams
      * @return mixed
      * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function call(string $method, string $uri, array $body = [], array $queryParams = [])
     {
diff --git a/src/HttpClientInterface.php b/src/HttpClientInterface.php
index 581529a..8aa0db0 100644
--- a/src/HttpClientInterface.php
+++ b/src/HttpClientInterface.php
@@ -2,14 +2,21 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient;
 
+use Jobcloud\Kafka\SchemaRegistryClient\Exception\SchemaRegistryExceptionInterface;
+use Psr\Http\Client\ClientExceptionInterface;
+use JsonException;
+
 interface HttpClientInterface
 {
     /**
      * @param string $method
      * @param string $uri
-     * @param array $body
-     * @param array $queryParams
+     * @param array<string,mixed> $body
+     * @param array<string,mixed> $queryParams
      * @return mixed
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function call(string $method, string $uri, array $body = [], array $queryParams = []);
 }
diff --git a/src/KafkaSchemaRegistryApiClient.php b/src/KafkaSchemaRegistryApiClient.php
index 6a76477..10267e6 100644
--- a/src/KafkaSchemaRegistryApiClient.php
+++ b/src/KafkaSchemaRegistryApiClient.php
@@ -2,10 +2,11 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient;
 
-use Buzz\Exception\RequestException;
-use Exception;
+use Jobcloud\Kafka\SchemaRegistryClient\Exception\SchemaRegistryExceptionInterface;
+use Psr\Http\Client\ClientExceptionInterface;
 use Jobcloud\Kafka\SchemaRegistryClient\Exception\SchemaNotFoundException;
 use Jobcloud\Kafka\SchemaRegistryClient\Exception\SubjectNotFoundException;
+use JsonException;
 
 class KafkaSchemaRegistryApiClient implements KafkaSchemaRegistryApiClientInterface
 {
@@ -24,7 +25,10 @@ public function __construct(HttpClientInterface $httpClient)
     }
 
     /**
-     * @return array
+     * @return array<string,mixed>
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function getSubjects(): array
     {
@@ -33,7 +37,10 @@ public function getSubjects(): array
 
     /**
      * @param string $subjectName
-     * @return array
+     * @return array<string,mixed>
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function getAllSubjectVersions(string $subjectName): array
     {
@@ -43,7 +50,10 @@ public function getAllSubjectVersions(string $subjectName): array
     /**
      * @param string $subjectName
      * @param string $version
-     * @return array
+     * @return array<string,mixed>
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function getSchemaByVersion(string $subjectName, string $version = self::VERSION_LATEST): array
     {
@@ -55,7 +65,10 @@ public function getSchemaByVersion(string $subjectName, string $version = self::
     /**
      * @param string $subjectName
      * @param string $version
-     * @return array
+     * @return array<string,mixed>
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function getSchemaDefinitionByVersion(string $subjectName, string $version = self::VERSION_LATEST): array
     {
@@ -71,6 +84,9 @@ public function getSchemaDefinitionByVersion(string $subjectName, string $versio
      * @param string $subjectName
      * @param string $version
      * @return int|null
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function deleteSchemaVersion(string $subjectName, string $version = self::VERSION_LATEST): ?int
     {
@@ -80,6 +96,9 @@ public function deleteSchemaVersion(string $subjectName, string $version = self:
     /**
      * @param int $id
      * @return string
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function getSchemaById(int $id): string
     {
@@ -89,7 +108,10 @@ public function getSchemaById(int $id): string
     /**
      * @param string $schema
      * @param string $subjectName
-     * @return array
+     * @return array<string,mixed>
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function registerNewSchemaVersion(string $subjectName, string $schema): array
     {
@@ -107,7 +129,9 @@ public function registerNewSchemaVersion(string $subjectName, string $schema): a
      * @param string $subjectName
      * @param string $version
      * @return bool
-     * @throws Exception
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function checkSchemaCompatibilityForVersion(
         string $subjectName,
@@ -132,7 +156,9 @@ public function checkSchemaCompatibilityForVersion(
     /**
      * @param string $subjectName
      * @return string|null
-     * @throws Exception
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function getSubjectCompatibilityLevel(string $subjectName): ?string
     {
@@ -148,6 +174,9 @@ public function getSubjectCompatibilityLevel(string $subjectName): ?string
      * @param string $subjectName
      * @param string $level
      * @return bool
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function setSubjectCompatibilityLevel(string $subjectName, string $level = self::LEVEL_FULL): bool
     {
@@ -157,6 +186,9 @@ public function setSubjectCompatibilityLevel(string $subjectName, string $level
 
     /**
      * @return string
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function getDefaultCompatibilityLevel(): string
     {
@@ -167,6 +199,9 @@ public function getDefaultCompatibilityLevel(): string
     /**
      * @param string $level
      * @return bool
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function setDefaultCompatibilityLevel(string $level = self::LEVEL_FULL): bool
     {
@@ -178,6 +213,9 @@ public function setDefaultCompatibilityLevel(string $level = self::LEVEL_FULL):
      * @param string $subjectName
      * @param string $schema
      * @return string|null
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function getVersionForSchema(string $subjectName, string $schema): ?string
     {
@@ -190,7 +228,7 @@ public function getVersionForSchema(string $subjectName, string $schema): ?strin
                         $this->createRequestBodyFromSchema($schema)
                     ) ?? [];
 
-            return (string) $results['version'];
+            return $results['version'];
         } catch (SubjectNotFoundException $e) {
             return null;
         } catch (SchemaNotFoundException $e) {
@@ -202,6 +240,9 @@ public function getVersionForSchema(string $subjectName, string $schema): ?strin
      * @param string $subjectName
      * @param string $schema
      * @return bool
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function isSchemaAlreadyRegistered(string $subjectName, string $schema): bool
     {
@@ -210,7 +251,10 @@ public function isSchemaAlreadyRegistered(string $subjectName, string $schema):
 
     /**
      * @param string $subjectName
-     * @return array
+     * @return array<string,mixed>
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function deleteSubject(string $subjectName): array
     {
@@ -220,7 +264,9 @@ public function deleteSubject(string $subjectName): array
     /**
      * @param string $subjectName
      * @return string|null
-     * @throws RequestException
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function getLatestSubjectVersion(string $subjectName): ?string
     {
@@ -232,6 +278,9 @@ public function getLatestSubjectVersion(string $subjectName): ?string
     /**
      * @param string $mode
      * @return bool
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function setImportMode(string $mode): bool
     {
@@ -241,10 +290,11 @@ public function setImportMode(string $mode): bool
 
     /**
      * @param string $schema
-     * @return array
+     * @return array<string,mixed>
+     * @throws JsonException
      */
     private function createRequestBodyFromSchema(string $schema): array
     {
-        return ['schema' => json_encode(json_decode($schema, true))];
+        return ['schema' => json_encode(json_decode($schema, true, 512, JSON_THROW_ON_ERROR), JSON_THROW_ON_ERROR)];
     }
 }
diff --git a/src/KafkaSchemaRegistryApiClientInterface.php b/src/KafkaSchemaRegistryApiClientInterface.php
index 1eeb7cf..248be99 100644
--- a/src/KafkaSchemaRegistryApiClientInterface.php
+++ b/src/KafkaSchemaRegistryApiClientInterface.php
@@ -2,6 +2,10 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient;
 
+use Jobcloud\Kafka\SchemaRegistryClient\Exception\SchemaRegistryExceptionInterface;
+use Psr\Http\Client\ClientExceptionInterface;
+use JsonException;
+
 interface KafkaSchemaRegistryApiClientInterface
 {
     public const VERSION_LATEST = 'latest';
@@ -19,27 +23,39 @@ interface KafkaSchemaRegistryApiClientInterface
     public const MODE_READWRITE = 'READWRITE';
 
     /**
-     * @return array
+     * @return array<string,mixed>
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function getSubjects(): array;
 
     /**
      * @param string $subjectName
-     * @return array
+     * @return array<string,mixed>
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function getAllSubjectVersions(string $subjectName): array;
 
     /**
      * @param string $subjectName
      * @param string $version
-     * @return array
+     * @return array<string,mixed>
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function getSchemaByVersion(string $subjectName, string $version = 'latest'): array;
 
     /**
      * @param string $subjectName
      * @param string $version
-     * @return array
+     * @return array<string,mixed>
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function getSchemaDefinitionByVersion(string $subjectName, string $version = self::VERSION_LATEST): array;
 
@@ -47,19 +63,28 @@ public function getSchemaDefinitionByVersion(string $subjectName, string $versio
      * @param string $subjectName
      * @param string $version
      * @return int|null
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function deleteSchemaVersion(string $subjectName, string $version = self::VERSION_LATEST): ?int;
 
     /**
      * @param int $id
      * @return string
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function getSchemaById(int $id): string;
 
     /**
      * @param string $subjectName
      * @param string $schema
-     * @return array
+     * @return array<string,mixed>
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function registerNewSchemaVersion(string $subjectName, string $schema): array;
 
@@ -68,6 +93,9 @@ public function registerNewSchemaVersion(string $subjectName, string $schema): a
      * @param string $schema
      * @param string $version
      * @return bool
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function checkSchemaCompatibilityForVersion(
         string $subjectName,
@@ -78,6 +106,9 @@ public function checkSchemaCompatibilityForVersion(
     /**
      * @param string $subjectName
      * @return string
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function getSubjectCompatibilityLevel(string $subjectName): ?string;
 
@@ -85,17 +116,26 @@ public function getSubjectCompatibilityLevel(string $subjectName): ?string;
      * @param string $subjectName
      * @param string $level
      * @return bool
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function setSubjectCompatibilityLevel(string $subjectName, string $level = self::LEVEL_FULL): bool;
 
     /**
      * @return string
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function getDefaultCompatibilityLevel(): string;
 
     /**
      * @param string $level
      * @return bool
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function setDefaultCompatibilityLevel(string $level = self::LEVEL_FULL): bool;
 
@@ -103,6 +143,9 @@ public function setDefaultCompatibilityLevel(string $level = self::LEVEL_FULL):
      * @param string $subjectName
      * @param string $schema
      * @return string|null
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function getVersionForSchema(string $subjectName, string $schema): ?string;
 
@@ -110,24 +153,34 @@ public function getVersionForSchema(string $subjectName, string $schema): ?strin
      * @param string $subjectName
      * @param string $schema
      * @return bool
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function isSchemaAlreadyRegistered(string $subjectName, string $schema): bool;
 
     /**
      * @param string $subjectName
-     * @return array
+     * @return array<string,mixed>
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function deleteSubject(string $subjectName): array;
 
     /**
      * @param string $mode
      * @return bool
+     * @throws ClientExceptionInterface
+     * @throws SchemaRegistryExceptionInterface
+     * @throws JsonException
      */
     public function setImportMode(string $mode): bool;
 
     /**
      * @param string $subjectName
      * @return string|null
+     * @throws JsonException
      */
     public function getLatestSubjectVersion(string $subjectName): ?string;
 }
diff --git a/src/ServiceProvider/KafkaSchemaRegistryApiClientProvider.php b/src/ServiceProvider/KafkaSchemaRegistryApiClientProvider.php
index 7013f03..26281ca 100644
--- a/src/ServiceProvider/KafkaSchemaRegistryApiClientProvider.php
+++ b/src/ServiceProvider/KafkaSchemaRegistryApiClientProvider.php
@@ -31,7 +31,7 @@ class KafkaSchemaRegistryApiClientProvider implements ServiceProviderInterface
     /**
      * @param Container $container
      */
-    public function register(Container $container)
+    public function register(Container $container): void
     {
         $this->checkRequiredOffsets($container);
 
@@ -58,7 +58,7 @@ public function register(Container $container)
                 /** @var ClientInterface $client */
                 $client = $container[self::CLIENT];
 
-                /** @var RequestFactoryInterface $psr17factory */
+                /** @var RequestFactoryInterface $requestFactory */
                 $requestFactory = $container[self::REQUEST_FACTORY];
 
                 return new HttpClient(
@@ -66,8 +66,8 @@ public function register(Container $container)
                     $requestFactory,
                     $container[self::ERROR_HANDLER],
                     $container[self::CONTAINER_KEY][self::SETTING_KEY_BASE_URL],
-                    $container[self::CONTAINER_KEY][self::SETTING_KEY_USERNAME] ?? null,
-                    $container[self::CONTAINER_KEY][self::SETTING_KEY_PASSWORD] ?? null
+                    $container[self::CONTAINER_KEY][self::SETTING_KEY_USERNAME],
+                    $container[self::CONTAINER_KEY][self::SETTING_KEY_PASSWORD]
                 );
             };
         }
@@ -82,7 +82,7 @@ public function register(Container $container)
         }
     }
 
-    private function checkRequiredOffsets(Container $container)
+    private function checkRequiredOffsets(Container $container): void
     {
 
         if (false === isset($container[self::CONTAINER_KEY][self::SETTING_KEY_BASE_URL])) {
diff --git a/tests/ErrorHandlerTest.php b/tests/ErrorHandlerTest.php
index 646a12a..2a59bc7 100644
--- a/tests/ErrorHandlerTest.php
+++ b/tests/ErrorHandlerTest.php
@@ -2,9 +2,9 @@
 
 namespace Jobcloud\Kafka\SchemaRegistryClient\Tests;
 
+use Buzz\Exception\ClientException;
 use Jobcloud\Kafka\SchemaRegistryClient\ErrorHandler;
 use Jobcloud\Kafka\SchemaRegistryClient\Exception\BackendDatastoreException;
-use Jobcloud\Kafka\SchemaRegistryClient\Exception\ClientException;
 use Jobcloud\Kafka\SchemaRegistryClient\Exception\CompatibilityException;
 use Jobcloud\Kafka\SchemaRegistryClient\Exception\ImportException;
 use Jobcloud\Kafka\SchemaRegistryClient\Exception\IncompatibileAvroSchemaException;
@@ -140,7 +140,7 @@ public function testExceptionThrowWithRequest(): void
 
         $this->expectException(BackendDatastoreException::class);
         $this->expectExceptionMessage(self::TEST_MESSAGE . sprintf(' (%s) with request body: %s', 'http://test.com', 'test body'));
-echo 'asdfasf';
+
         $errorHandler->handleError($responseMock, 'http://test.com', $requestMock);
     }
 
diff --git a/tests/KafkaSchemaRegistryApiClientProviderTest.php b/tests/KafkaSchemaRegistryApiClientProviderTest.php
index 9263e2b..61f0c82 100644
--- a/tests/KafkaSchemaRegistryApiClientProviderTest.php
+++ b/tests/KafkaSchemaRegistryApiClientProviderTest.php
@@ -22,15 +22,15 @@ public function testDefaultContainersAndServicesSetWithMinimalConfig(): void
     {
         $container = new Container();
 
-        $this->assertArrayNotHasKey('kafka.schema.registry', $container);
-        $this->assertArrayNotHasKey('username', $container['kafka.schema.registry'] ?? []);
-        $this->assertArrayNotHasKey('password', $container['kafka.schema.registry'] ?? []);
-        $this->assertArrayNotHasKey('base.url', $container['kafka.schema.registry'] ?? []);
-        $this->assertArrayNotHasKey('kafka.schema.registry.client', $container);
-        $this->assertArrayNotHasKey('kafka.schema.registry.request.factory', $container);
-        $this->assertArrayNotHasKey('kafka.schema.registry.client.http', $container);
-        $this->assertArrayNotHasKey('kafka.schema.registry.client.api', $container);
-        $this->assertArrayNotHasKey('kafka.schema.registry.error.handler', $container);
+        self::assertArrayNotHasKey('kafka.schema.registry', $container);
+        self::assertArrayNotHasKey('username', $container['kafka.schema.registry'] ?? []);
+        self::assertArrayNotHasKey('password', $container['kafka.schema.registry'] ?? []);
+        self::assertArrayNotHasKey('base.url', $container['kafka.schema.registry'] ?? []);
+        self::assertArrayNotHasKey('kafka.schema.registry.client', $container);
+        self::assertArrayNotHasKey('kafka.schema.registry.request.factory', $container);
+        self::assertArrayNotHasKey('kafka.schema.registry.client.http', $container);
+        self::assertArrayNotHasKey('kafka.schema.registry.client.api', $container);
+        self::assertArrayNotHasKey('kafka.schema.registry.error.handler', $container);
 
         $container['kafka.schema.registry'] = [
             'base.url' => 'http://some-url',
@@ -40,23 +40,45 @@ public function testDefaultContainersAndServicesSetWithMinimalConfig(): void
 
         $container->register(new KafkaSchemaRegistryApiClientProvider());
 
-        $this->assertArrayHasKey('kafka.schema.registry', $container);
-        $this->assertArrayHasKey('username', $container['kafka.schema.registry']);
-        $this->assertArrayHasKey('password', $container['kafka.schema.registry']);
-        $this->assertArrayHasKey('kafka.schema.registry.client', $container);
-        $this->assertArrayHasKey('kafka.schema.registry.request.factory', $container);
-        $this->assertArrayHasKey('kafka.schema.registry.client.http', $container);
-        $this->assertArrayHasKey('kafka.schema.registry.client.api', $container);
-        $this->assertArrayHasKey('kafka.schema.registry.error.handler', $container);
-
-        $this->assertInstanceOf(RequestFactoryInterface::class, $container['kafka.schema.registry.request.factory']);
-        $this->assertInstanceOf(HttpClientInterface::class, $container['kafka.schema.registry.client.http']);
-        $this->assertInstanceOf(ErrorHandlerInterface::class, $container['kafka.schema.registry.error.handler']);
-        $this->assertInstanceOf(
+        self::assertArrayHasKey('kafka.schema.registry', $container);
+        self::assertArrayHasKey('username', $container['kafka.schema.registry']);
+        self::assertArrayHasKey('password', $container['kafka.schema.registry']);
+        self::assertArrayHasKey('kafka.schema.registry.client', $container);
+        self::assertArrayHasKey('kafka.schema.registry.request.factory', $container);
+        self::assertArrayHasKey('kafka.schema.registry.client.http', $container);
+        self::assertArrayHasKey('kafka.schema.registry.client.api', $container);
+        self::assertArrayHasKey('kafka.schema.registry.error.handler', $container);
+
+        $client = $container['kafka.schema.registry.client.http'];
+
+        self::assertInstanceOf(RequestFactoryInterface::class, $container['kafka.schema.registry.request.factory']);
+        self::assertInstanceOf(HttpClientInterface::class, $client);
+        self::assertInstanceOf(ErrorHandlerInterface::class, $container['kafka.schema.registry.error.handler']);
+        self::assertInstanceOf(
             KafkaSchemaRegistryApiClientInterface::class,
             $container['kafka.schema.registry.client.api']
         );
+    }
+
+    public function testSuccessWithMissingAuth(): void
+    {
+        $container = new Container();
+
+        $container['kafka.schema.registry'] = [
+            'base.url' => 'http://some-url'
+        ];
+
+        $container->register(new KafkaSchemaRegistryApiClientProvider());
 
+        $client = $container['kafka.schema.registry.client.http'];
+
+        self::assertInstanceOf(HttpClientInterface::class, $client);
+        self::assertEquals(
+            $container['kafka.schema.registry']['password'],
+            self::getPropertyValue($client, 'password')
+        );
+        self::assertNull(self::getPropertyValue($client, 'username'));
+        self::assertNull(self::getPropertyValue($client, 'password'));
     }
 
     public function testFailOnMissingBaseUrlInContainer(): void
@@ -68,8 +90,8 @@ public function testFailOnMissingBaseUrlInContainer(): void
             'password' => 'p1',
         ];
 
-        $this->expectException(LogicException::class);
-        $this->expectExceptionMessage('Missing schema registry URL, please set it under "base.url" container offset');
+        self::expectException(LogicException::class);
+        self::expectExceptionMessage('Missing schema registry URL, please set it under "base.url" container offset');
 
         $container->register(new KafkaSchemaRegistryApiClientProvider());
     }
@@ -85,14 +107,14 @@ public function testUserNameAndPasswordFromSettingsArePassedToHttpClient(): void
         ];
 
         $container->register(new KafkaSchemaRegistryApiClientProvider());
-        $this->assertSame(
+        self::assertSame(
             $container['kafka.schema.registry']['username'],
-            $this->getPropertyValue($container['kafka.schema.registry.client.http'], 'username')
+            self::getPropertyValue($container['kafka.schema.registry.client.http'], 'username')
         );
 
-        $this->assertSame(
+        self::assertSame(
             $container['kafka.schema.registry']['password'],
-            $this->getPropertyValue($container['kafka.schema.registry.client.http'], 'password')
+            self::getPropertyValue($container['kafka.schema.registry.client.http'], 'password')
         );
 
     }
diff --git a/tests/KafkaSchemaRegistryApiClientTest.php b/tests/KafkaSchemaRegistryApiClientTest.php
index 2f09a39..58e0ad6 100644
--- a/tests/KafkaSchemaRegistryApiClientTest.php
+++ b/tests/KafkaSchemaRegistryApiClientTest.php
@@ -212,15 +212,18 @@ public function testGetDefaultCompatibiltyLeveWhenGetSubjectCompatibilityLevelTh
         $httpClientMock = $this->getHttpClientMock();
 
         $httpClientMock
-            ->expects($this->at(0))
+            ->expects(self::exactly(2))
             ->method('call')
-            ->with('GET', sprintf('config/%s', self::TEST_SUBJECT_NAME))
-            ->willThrowException(new SubjectNotFoundException());
-
-        $httpClientMock
-            ->expects($this->at(1))
-            ->method('call')
-            ->willReturn(['compatibilityLevel' => KafkaSchemaRegistryApiClientInterface::LEVEL_FULL]);
+            ->withConsecutive(
+                ['GET', sprintf('config/%s', self::TEST_SUBJECT_NAME)],
+                []
+            )
+            ->will(
+                $this->onConsecutiveCalls(
+                    $this->throwException(new SubjectNotFoundException()),
+                    ['compatibilityLevel' => KafkaSchemaRegistryApiClientInterface::LEVEL_FULL]
+                )
+            );
 
         $api = new KafkaSchemaRegistryApiClient($httpClientMock);
         $result = $api->getSubjectCompatibilityLevel(self::TEST_SUBJECT_NAME);