diff --git a/README.md b/README.md
index 8eeddf2..8486c60 100644
--- a/README.md
+++ b/README.md
@@ -24,7 +24,7 @@ SimpleXLSX: very fast excel import/export
 https://github.com/shuchkin/simplexlsx
 https://github.com/shuchkin/simplexlsxgen
 
-This package will prioritize installed library, by order of performance. You can also pick your preferred adapter for each format like this:
+This package will prioritize installed library, by order of performance. You can also pick your preferred default adapter for each format like this:
 
 ```php
 SpreadCompat::$preferredCsvAdapter = SpreadCompat::NATIVE; // our native csv adapter is the fastest
@@ -82,6 +82,18 @@ $options->separator = ";";
 $data = iterator_to_array(SpreadCompat::read('myfile.csv', $options));
 ```
 
+## Setting the adapter
+
+Instead of relying on the static variables, you can choose which adapter to use:
+
+```php
+$csvData = SpreadCompat::readString($csv, adapter: SpreadCompat::NATIVE);
+// or
+$options = new Options();
+$options->adapter = SpreadCompat::NATIVE;
+$csvData = SpreadCompat::readString($csv, $options);
+```
+
 ## Worksheets
 
 This package supports only 1 worksheet, as it is meant to be able to replace csv by xlsx or vice versa
diff --git a/src/Common/Options.php b/src/Common/Options.php
index 2d61d6f..3594b1a 100644
--- a/src/Common/Options.php
+++ b/src/Common/Options.php
@@ -4,7 +4,12 @@
 
 namespace LeKoala\SpreadCompat\Common;
 
-class Options
+use ArrayAccess;
+
+/**
+ * @implements ArrayAccess<string,mixed>
+ */
+class Options implements ArrayAccess
 {
     use Configure;
 
@@ -45,4 +50,24 @@ public function __construct(...$opts)
             $this->configure(...$opts);
         }
     }
+
+    public function offsetExists(mixed $offset): bool
+    {
+        return property_exists($this, $offset);
+    }
+
+    public function offsetGet(mixed $offset): mixed
+    {
+        return $this->$offset ?? null;
+    }
+
+    public function offsetSet(mixed $offset, mixed $value): void
+    {
+        $this->$offset = $value;
+    }
+
+    public function offsetUnset(mixed $offset): void
+    {
+        $this->$offset = null;
+    }
 }
diff --git a/src/SpreadCompat.php b/src/SpreadCompat.php
index 7b77a23..458e3e6 100644
--- a/src/SpreadCompat.php
+++ b/src/SpreadCompat.php
@@ -80,7 +80,7 @@ public static function getAdapter(string $ext): SpreadInterface
     {
         $name = self::getAdapterName($ext);
         $ext = ucfirst($ext);
-        $class = 'LeKoala\\SpreadCompat\\' . $ext . '\\' . $name;
+        $class = '\\LeKoala\\SpreadCompat\\' . $ext . '\\' . $name;
         if (!class_exists($class)) {
             throw new Exception("Invalid adapter $class");
         }
@@ -90,7 +90,7 @@ public static function getAdapter(string $ext): SpreadInterface
     public static function getAdapterByName(string $ext, string $name): SpreadInterface
     {
         $ext = ucfirst($ext);
-        $class = 'LeKoala\\SpreadCompat\\' . $ext . '\\' . $name;
+        $class = '\\LeKoala\\SpreadCompat\\' . $ext . '\\' . $name;
         if (!class_exists($class)) {
             throw new Exception("Invalid adapter $class");
         }
@@ -105,6 +105,31 @@ public static function getAdapterForFile(string $filename, string $ext = null):
         return self::getAdapter($ext);
     }
 
+    /**
+     * @param array<int,array<string,string>>|array<string,string> $opts
+     * @param ?string $ext
+     * @return ?SpreadInterface
+     */
+    public static function getAdapterFromOpts(array $opts, ?string $ext = null): ?SpreadInterface
+    {
+        $name = $opts[0]['adapter'] ?? $opts['adapter'] ?? null;
+        if ($name === null || !is_string($name)) {
+            return null;
+        }
+        // It's a full class name
+        if (is_a($name, SpreadInterface::class, true)) {
+            return new ($name);
+        }
+        if (!$ext) {
+            $ext = self::getExtensionFromOpts($opts);
+        }
+        // It's a partial name, we need the extension for this
+        if ($ext) {
+            return self::getAdapterByName($ext, $name);
+        }
+        return null;
+    }
+
     /**
      * @return string
      */
@@ -128,10 +153,13 @@ public static function isTempFile(string $file): bool
      */
     public static function getExtensionForContent(string $contents): string
     {
-        if (ctype_print($contents)) {
-            $ext = self::EXT_CSV;
-        } else {
+        //@link https://gist.github.com/leommoore/f9e57ba2aa4bf197ebc5
+        //50 4b 03 04
+        $header = strtoupper(substr(bin2hex($contents), 0, 8));
+        if ($header === '504B0304') {
             $ext = self::EXT_XLSX;
+        } else {
+            $ext = self::EXT_CSV;
         }
         return $ext;
     }
@@ -269,8 +297,8 @@ public static function excelCell(int $row = 0, int $column = 0, bool $absolute =
      */
     protected static function getExtensionFromOpts(array $opts, ?string $fallback = null): ?string
     {
-        //@phpstan-ignore-next-line PHPStan doesn't detect properly our return type
-        return $opts[0]['extension'] ?? $opts['extension'] ?? $fallback;
+        $ext = $opts[0]['extension'] ?? $opts['extension'] ?? $fallback;
+        return is_string($ext) ? $ext : null;
     }
 
     public static function read(
@@ -278,7 +306,11 @@ public static function read(
         ...$opts
     ): Generator {
         $ext = self::getExtensionFromOpts($opts);
-        return static::getAdapterForFile($filename, $ext)->readFile($filename, ...$opts);
+        $adapter = self::getAdapterFromOpts($opts, $ext);
+        if (!$adapter) {
+            $adapter = static::getAdapterForFile($filename, $ext);
+        }
+        return $adapter->readFile($filename, ...$opts);
     }
 
     public static function readString(
@@ -290,7 +322,11 @@ public static function readString(
         if ($ext === null) {
             $ext = self::getExtensionForContent($contents);
         }
-        return static::getAdapter($ext)->readString($contents, ...$opts);
+        $adapter = self::getAdapterFromOpts($opts, $ext);
+        if (!$adapter) {
+            $adapter = static::getAdapter($ext);
+        }
+        return $adapter->readString($contents, ...$opts);
     }
 
     public static function write(
@@ -299,7 +335,27 @@ public static function write(
         ...$opts
     ): bool {
         $ext = self::getExtensionFromOpts($opts);
-        return static::getAdapterForFile($filename, $ext)->writeFile($data, $filename, ...$opts);
+        $adapter = self::getAdapterFromOpts($opts, $ext);
+        if (!$adapter) {
+            $adapter = static::getAdapterForFile($filename, $ext);
+        }
+        return $adapter->writeFile($data, $filename, ...$opts);
+    }
+
+    public static function writeString(
+        iterable $data,
+        string $ext = null,
+        ...$opts
+    ): string {
+        $ext = self::getExtensionFromOpts($opts);
+        $adapter = self::getAdapterFromOpts($opts, $ext);
+        if (!$adapter && !$ext) {
+            throw new Exception("No adapter or extension specified for string");
+        }
+        if (!$adapter) {
+            $adapter = static::getAdapter($ext);
+        }
+        return $adapter->writeString($data, ...$opts);
     }
 
     public static function output(
@@ -311,6 +367,10 @@ public static function output(
         if ($ext) {
             $filename = self::ensureExtension($filename, $ext);
         }
-        static::getAdapterForFile($filename, $ext)->output($data, $filename, ...$opts);
+        $adapter = self::getAdapterFromOpts($opts, $ext);
+        if (!$adapter) {
+            $adapter = static::getAdapterForFile($filename, $ext);
+        }
+        $adapter->output($data, $filename, ...$opts);
     }
 }
diff --git a/tests/SpreadCompatCommonTest.php b/tests/SpreadCompatCommonTest.php
index c6cb994..3c8560a 100644
--- a/tests/SpreadCompatCommonTest.php
+++ b/tests/SpreadCompatCommonTest.php
@@ -15,9 +15,15 @@ public function testCanUseOptions()
     {
         $options = new Options();
         $options->separator = ";";
+
+        // Can use configure
         $csv = new Native();
         $csv->configure($options);
         $this->assertEquals(";", $csv->separator);
+
+        // Or use directly
+        $csvData = SpreadCompat::read(__DIR__ . '/data/separator.csv', $options);
+        $this->assertNotEmpty(iterator_to_array($csvData));
     }
 
     public function testCanUseNamedArguments()
@@ -61,4 +67,54 @@ public function testCanReadTemp()
         $this->expectException(\Exception::class);
         $csvData = SpreadCompat::read($filename);
     }
+
+    public function testCanDetectContentType()
+    {
+        $csv = file_get_contents(__DIR__ . '/data/basic.csv');
+        $this->assertTrue('csv' == SpreadCompat::getExtensionForContent($csv), "Content is: $csv");
+        $xlsx = file_get_contents(__DIR__ . '/data/basic.xlsx');
+        $this->assertTrue('xlsx' == SpreadCompat::getExtensionForContent($xlsx), "Content is: $xlsx");
+    }
+
+    public function testCanSpecifyAdapter()
+    {
+        // Csv, with extension in opts or as param
+        $adapter = SpreadCompat::getAdapterFromOpts([
+            'adapter' => SpreadCompat::NATIVE,
+            'extension' => 'csv'
+        ]);
+        $this->assertInstanceOf(\LeKoala\SpreadCompat\Csv\Native::class, $adapter);
+        $adapter = SpreadCompat::getAdapterFromOpts([
+            'adapter' => SpreadCompat::PHP_SPREADSHEET,
+            'extension' => 'csv'
+        ]);
+        $this->assertInstanceOf(\LeKoala\SpreadCompat\Csv\PhpSpreadsheet::class, $adapter);
+        $adapter = SpreadCompat::getAdapterFromOpts([
+            'adapter' => SpreadCompat::PHP_SPREADSHEET,
+        ], 'csv');
+        $this->assertInstanceOf(\LeKoala\SpreadCompat\Csv\PhpSpreadsheet::class, $adapter);
+        // Xlsx
+        $adapter = SpreadCompat::getAdapterFromOpts([
+            'adapter' => SpreadCompat::PHP_SPREADSHEET,
+        ], 'xlsx');
+        $this->assertInstanceOf(\LeKoala\SpreadCompat\Xlsx\PhpSpreadsheet::class, $adapter);
+        $adapter = SpreadCompat::getAdapterFromOpts([
+            'adapter' => SpreadCompat::NATIVE,
+        ], 'xlsx');
+        $this->assertInstanceOf(\LeKoala\SpreadCompat\Xlsx\Native::class, $adapter);
+        // Can specify full class
+        $adapter = SpreadCompat::getAdapterFromOpts([
+            'adapter' => \LeKoala\SpreadCompat\Xlsx\Native::class,
+        ], 'xlsx');
+        $this->assertInstanceOf(\LeKoala\SpreadCompat\Xlsx\Native::class, $adapter);
+
+        // Make sure it actually works
+        $csv = file_get_contents(__DIR__ . '/data/basic.csv');
+        $csvData = SpreadCompat::readString($csv, null, adapter: SpreadCompat::NATIVE);
+        $this->assertNotEmpty(iterator_to_array($csvData));
+        $options = new Options();
+        $options->adapter = SpreadCompat::NATIVE;
+        $csvData = SpreadCompat::readString($csv, null, $options);
+        $this->assertNotEmpty(iterator_to_array($csvData));
+    }
 }