diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 0000000..13a634c
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,10 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_size = 4
+indent_style = space
+insert_final_newline = true
+max_line_length = 120
+trim_trailing_whitespace = true
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..f7f520e
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+.idea
+/vendor/
+composer.lock
diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..d4cf59c
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,11 @@
+# Changelog
+All notable changes to `SSL converter` will be documented in this file.
+
+Updates should follow the [Keep a CHANGELOG](http://keepachangelog.com/) principles.
+
+## Unreleased
+[Compare v0.0.1 - Unreleased](https://github.com/exonet/ssl-converter/compare/v0.0.1...develop)
+
+## [v0.0.1](https://github.com/exonet/ssl-converter/releases/tag/v0.0.1) - 2019-01-30
+### Added
+- Initial release.
diff --git a/README.md b/README.md
index 3fa9548..932a470 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,53 @@
-# ssl-converter
+# SSL converter
 PHP package to convert an SSL certificate to various formats (e.g PKC12, PEM).
+
+## Install
+Via Composer
+
+``` bash
+$ composer require exonet/ssl-converter
+```
+
+## Example usage
+The example below shows how combine separate contents of a certificate to a combined PEM string.
+ - `crt` The certificate (typically the contents of `.crt` file).
+ - `key` The private key (typically the contents of the `.key` file)
+ - `ca bundle` The certificate of the intermediate and/or the trusted root certificate
+
+```php
+// Initialise a new SSL converter.
+$converter = new Converter();
+
+// Setup the plain format class that should be converter.
+$plain = new Plain();
+$plain
+    ->setKey('-----BEGIN PRIVATE KEY-----
+...
+-----END PRIVATE KEY-----
+')
+    ->setCrt('-----BEGIN CERTIFICATE-----
+...
+-----END CERTIFICATE-----
+')
+    ->setCaBundle('-----BEGIN CERTIFICATE-----
+...
+-----END CERTIFICATE-----
+');
+
+// Convert the plain certificate.
+$pem = $converter
+    ->from($plain)
+    ->to(new Pem());
+    
+// Save as zip file:
+$pem->asZip('./');
+
+// Get an array with the certificate files:
+print_r($pem->asFiles());
+
+// Get the certificate as string:
+print_r($pem->asString());
+```
+
+## Change log
+Please see [CHANGELOG](CHANGELOG.md) for more information on what has changed recently.
diff --git a/composer.json b/composer.json
new file mode 100644
index 0000000..3cfd1b4
--- /dev/null
+++ b/composer.json
@@ -0,0 +1,25 @@
+{
+    "name": "exonet/ssl-converter",
+    "description": "PHP package to convert an SSL certificate to various formats (e.g PKC12, PEM).",
+    "type": "library",
+    "license": "MIT",
+    "authors": [
+        {
+            "name": "Exonet B.V.",
+            "email": "development@exonet.nl"
+        }
+    ],
+    "require": {
+        "php": "~7.1",
+        "ext-openssl": "*",
+        "ext-zip": "*"
+    },
+    "autoload": {
+        "psr-4": {
+            "Exonet\\SslConverter\\": "src"
+        }
+    },
+    "config": {
+        "sort-packages": true
+    }
+}
diff --git a/src/Converter.php b/src/Converter.php
new file mode 100644
index 0000000..c4d2ed8
--- /dev/null
+++ b/src/Converter.php
@@ -0,0 +1,143 @@
+<?php
+
+namespace Exonet\SslConverter;
+
+use Exonet\SslConverter\Exceptions\ZipException;
+use Exonet\SslConverter\Formats\FormatInterface;
+use ZipArchive;
+
+class Converter
+{
+    /**
+     * @var FormatInterface The input format to be converted.
+     */
+    protected $to;
+
+    /**
+     * @var FormatInterface The output format to convert to.
+     */
+    protected $from;
+
+    /**
+     * @var string The certificate name.
+     */
+    protected $certificateName = 'certificate';
+
+    /**
+     * Set the name of the certificate.
+     *
+     * @param string $certificateName The certificate.
+     *
+     * @return $this The current Converter instance.
+     */
+    public function setName(string $certificateName) : self
+    {
+        $this->certificateName = $certificateName;
+
+        return $this;
+    }
+
+    /**
+     * Set the format that should be converted.
+     *
+     * @param FormatInterface $from The input format to be converted.
+     *
+     * @return $this Instance of this class.
+     */
+    public function from(FormatInterface $from) : self
+    {
+        $this->from = $from;
+
+        return $this;
+    }
+
+    /**
+     * Set the format that should be converted to.
+     *
+     * @param FormatInterface $to The output format to convert to.
+     *
+     * @return $this Instance of this class
+     */
+    public function to(FormatInterface $to) : self
+    {
+        $this->to = $to;
+
+        return $this;
+    }
+
+    /**
+     * Convert the input format to the provided output format as a string.
+     *
+     * @return string The converted format as a string that can be saved to a file.
+     *
+     * @throws Exceptions\InvalidResource When the provided certificate is invalid.
+     * @throws Exceptions\MissingRequiredInformation When some required certificate data is missing.
+     */
+    public function asString() : string
+    {
+        return $this->to
+            ->setName($this->certificateName)
+            ->setPlain($this->from->getPlain())
+            ->toString();
+    }
+
+    /**
+     * Convert the input format to the provided output format as an array of files. The array key is the file name, the
+     * array value the file contents.
+     *
+     * @return string[] The converted format as an array of files that can be saved to a file.
+     *
+     * @throws Exceptions\InvalidResource When the provided certificate is invalid.
+     * @throws Exceptions\MissingRequiredInformation When some required certificate data is missing.
+     */
+    public function asFiles() : array
+    {
+        return $this->to
+            ->setName($this->certificateName)
+            ->setPlain($this->from->getPlain())
+            ->export();
+    }
+
+    /**
+     * Convert the input format to the provided output format and save the file (or files) as zip.
+     *
+     * @param string $path The path where to store the zip file.
+     *
+     * @return bool True when the zip is created and stored.
+     *
+     * @throws Exceptions\InvalidResource When the provided certificate is invalid.
+     * @throws Exceptions\MissingRequiredInformation When some required certificate data is missing.
+     * @throws ZipException When the files can not be zipped.
+     */
+    public function asZip(string $path) : bool
+    {
+        $filename = sprintf('%s/%s.zip', rtrim($path, '/'), $this->certificateName);
+
+        if (!is_dir($path) || !is_writable($path)) {
+            throw new ZipException(sprintf('The directory [%s] is does not exists or is not writable.', $path));
+        }
+
+        if (is_file($filename) && !is_writable($filename)) {
+            throw new ZipException(sprintf('The file [%s] already exists and is not writable.', $filename));
+        }
+
+        $files = $this->to
+            ->setName($this->certificateName)
+            ->setPlain($this->from->getPlain())
+            ->export();
+
+        $zip = new ZipArchive();
+        $zip->open($filename, ZipArchive::CREATE);
+        foreach ($files as $name => $content) {
+            $zip->addFromString($name, $content);
+        }
+
+        if ($zip->status !== 0) {
+            throw new ZipException($zip->getStatusString());
+        }
+
+        $zip->close();
+
+        return file_exists($filename);
+    }
+}
diff --git a/src/Exceptions/InvalidResource.php b/src/Exceptions/InvalidResource.php
new file mode 100644
index 0000000..1bc7508
--- /dev/null
+++ b/src/Exceptions/InvalidResource.php
@@ -0,0 +1,7 @@
+<?php
+
+namespace Exonet\SslConverter\Exceptions;
+
+class InvalidResource extends SslConverterException
+{
+}
diff --git a/src/Exceptions/MissingRequiredInformation.php b/src/Exceptions/MissingRequiredInformation.php
new file mode 100644
index 0000000..1735447
--- /dev/null
+++ b/src/Exceptions/MissingRequiredInformation.php
@@ -0,0 +1,7 @@
+<?php
+
+namespace Exonet\SslConverter\Exceptions;
+
+class MissingRequiredInformation extends SslConverterException
+{
+}
diff --git a/src/Exceptions/NotImplementedException.php b/src/Exceptions/NotImplementedException.php
new file mode 100644
index 0000000..aff6153
--- /dev/null
+++ b/src/Exceptions/NotImplementedException.php
@@ -0,0 +1,7 @@
+<?php
+
+namespace Exonet\SslConverter\Exceptions;
+
+class NotImplementedException extends SslConverterException
+{
+}
diff --git a/src/Exceptions/SslConverterException.php b/src/Exceptions/SslConverterException.php
new file mode 100644
index 0000000..b2b357a
--- /dev/null
+++ b/src/Exceptions/SslConverterException.php
@@ -0,0 +1,9 @@
+<?php
+
+namespace Exonet\SslConverter\Exceptions;
+
+use Exception;
+
+class SslConverterException extends Exception
+{
+}
diff --git a/src/Exceptions/ZipException.php b/src/Exceptions/ZipException.php
new file mode 100644
index 0000000..cd90678
--- /dev/null
+++ b/src/Exceptions/ZipException.php
@@ -0,0 +1,7 @@
+<?php
+
+namespace Exonet\SslConverter\Exceptions;
+
+class ZipException extends SslConverterException
+{
+}
diff --git a/src/Formats/AbstractFormat.php b/src/Formats/AbstractFormat.php
new file mode 100644
index 0000000..0261bcc
--- /dev/null
+++ b/src/Formats/AbstractFormat.php
@@ -0,0 +1,89 @@
+<?php
+
+namespace Exonet\SslConverter\Formats;
+
+use Exonet\SslConverter\Exceptions\NotImplementedException;
+
+abstract class AbstractFormat implements FormatInterface
+{
+    /**
+     * @var Plain The plain certificate required for exporting.
+     */
+    protected $plainCertificate;
+
+    /**
+     * @var mixed[] List with options for the format.
+     */
+    protected $options = [];
+
+    /**
+     * @var string The certificate name.
+     */
+    protected $name = 'certificate';
+
+    /**
+     * AbstractFormat constructor.
+     *
+     * @param mixed[] $options The (optional) array with options for this format.
+     */
+    public function __construct(array $options = [])
+    {
+        $this->setOptions($options);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function setName(string $name) : FormatInterface
+    {
+        $this->name = $name;
+
+        return $this;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getName() : string
+    {
+        return $this->name;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function setPlain(Plain $plain) : FormatInterface
+    {
+        $this->plainCertificate = $plain;
+
+        return $this;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function setOptions(array $options) : FormatInterface
+    {
+        $this->options = $options;
+
+        return $this;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getOptions() : array
+    {
+        return $this->options;
+    }
+
+    /**
+     * @inheritdoc
+     *
+     * @throws NotImplementedException When this method is not implemented.
+     */
+    public function getPlain() : Plain
+    {
+        throw new NotImplementedException('The [getPlain] method is not implemented for this format.');
+    }
+}
diff --git a/src/Formats/FormatInterface.php b/src/Formats/FormatInterface.php
new file mode 100644
index 0000000..7fdfa5f
--- /dev/null
+++ b/src/Formats/FormatInterface.php
@@ -0,0 +1,77 @@
+<?php
+
+namespace Exonet\SslConverter\Formats;
+
+use Exonet\SslConverter\Exceptions\InvalidResource;
+use Exonet\SslConverter\Exceptions\MissingRequiredInformation;
+
+interface FormatInterface
+{
+    /**
+     * Set the certificate name.
+     *
+     * @param string $certificateName The certificate name.
+     *
+     * @return $this The current format instance.
+     */
+    public function setName(string $certificateName) : FormatInterface;
+
+    /**
+     * Get the certificate name.
+     *
+     * @return string The certificate name.
+     */
+    public function getName() : string;
+
+    /**
+     * Export the format to an array with the certificate data.
+     *
+     * @return string[] A list with the certificate files. The key is the file name, the value the file contents.
+     *
+     * @throws InvalidResource When the provided certificate is invalid.
+     * @throws MissingRequiredInformation When some required certificate data is missing.
+     */
+    public function export() : array;
+
+    /**
+     * Export the format to a string that can be saved to a file.
+     *
+     * @return string The format as a string that can be saved to a file.
+     *
+     * @throws InvalidResource When the provided certificate is invalid.
+     * @throws MissingRequiredInformation When some required certificate data is missing.
+     */
+    public function toString() : string;
+
+    /**
+     * Return a plain instance of this format version.
+     *
+     * @return Plain The plain instance of this format.
+     */
+    public function getPlain() : Plain;
+
+    /**
+     * Set the plain instance of this format version.
+     *
+     * @param Plain $plain The plain instance of this format.
+     *
+     * @return $this The current format instance.
+     */
+    public function setPlain(Plain $plain) : FormatInterface;
+
+    /**
+     * Set the options for this format version.
+     *
+     * @param mixed[] $options The options.
+     *
+     * @return $this The current format instance.
+     */
+    public function setOptions(array $options) : FormatInterface;
+
+    /**
+     * Get the options for this format version.
+     *
+     * @return mixed[] The options set for this format.
+     */
+    public function getOptions() : array;
+}
diff --git a/src/Formats/Pem.php b/src/Formats/Pem.php
new file mode 100644
index 0000000..b4ca4d8
--- /dev/null
+++ b/src/Formats/Pem.php
@@ -0,0 +1,41 @@
+<?php
+
+namespace Exonet\SslConverter\Formats;
+
+use Exonet\SslConverter\Exceptions\InvalidResource;
+use Exonet\SslConverter\Exceptions\MissingRequiredInformation;
+
+class Pem extends AbstractFormat
+{
+    /**
+     * @inheritdoc
+     */
+    public function export() : array
+    {
+        return [
+            $this->name.'.pem' => $this->toString(),
+        ];
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function toString() : string
+    {
+        $key = $this->plainCertificate->getKey();
+        $crt = $this->plainCertificate->getCrt();
+        $caBundle = $this->plainCertificate->getCaBundle();
+
+        if (!$crt || !$caBundle) {
+            throw new MissingRequiredInformation('The following fields are required for PEM: CRT, CA Bundle.');
+        }
+
+        // If there is a key, prepend the certificate content with the key.
+        $content = $key ? $key.$crt.$caBundle : $crt.$caBundle;
+        if (!openssl_x509_read($content)) {
+            throw new InvalidResource('Invalid certificate provided.');
+        }
+
+        return $content;
+    }
+}
diff --git a/src/Formats/Pkcs12.php b/src/Formats/Pkcs12.php
new file mode 100644
index 0000000..ca7fca8
--- /dev/null
+++ b/src/Formats/Pkcs12.php
@@ -0,0 +1,40 @@
+<?php
+
+namespace Exonet\SslConverter\Formats;
+
+use Exonet\SslConverter\Exceptions\InvalidResource;
+use Exonet\SslConverter\Exceptions\MissingRequiredInformation;
+
+class Pkcs12 extends AbstractFormat
+{
+    /**
+     * @inheritdoc
+     */
+    public function export() : array
+    {
+        return [
+            $this->name.'.pfx' => $this->toString(),
+        ];
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function toString() : string
+    {
+        $key = $this->plainCertificate->getKey();
+        $crt = $this->plainCertificate->getCrt();
+        $caBundle = $this->plainCertificate->getCaBundle();
+        $password = $this->options['password'] ?? false;
+
+        if (!$key || !$crt || !$caBundle || !$password) {
+            throw new MissingRequiredInformation('The following fields are required for PKCS12: key, CRT, CA Bundle, password.');
+        }
+
+        if (!openssl_pkcs12_export($crt, $pkc12, $key, $password, ['extracerts' => $caBundle])) {
+            throw new InvalidResource('Invalid certificate provided.');
+        };
+
+        return $pkc12;
+    }
+}
diff --git a/src/Formats/Plain.php b/src/Formats/Plain.php
new file mode 100644
index 0000000..880bf49
--- /dev/null
+++ b/src/Formats/Plain.php
@@ -0,0 +1,121 @@
+<?php
+
+namespace Exonet\SslConverter\Formats;
+
+class Plain extends AbstractFormat
+{
+    /**
+     * @var string The certificate string, typically the contents of the '.crt' file.
+     */
+    protected $crt;
+
+    /**
+     * @var string The private key to encrypt/decrypt the certificate typically the contents of the '.key' file.
+     */
+    protected $key;
+
+    /**
+     * @var string The certificate strings of the intermediate and/or the trusted root.
+     */
+    protected $caBundle;
+
+    /**
+     * {@inheritdoc}
+     */
+    public function export() : array
+    {
+        return [
+            $this->name.'.key' => $this->plainCertificate->getKey(),
+            $this->name.'.crt' => $this->plainCertificate->getCrt(),
+            $this->name.'.ca-bundle' => $this->plainCertificate->getCaBundle(),
+        ];
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function toString() : string
+    {
+        return $this->plainCertificate->getCrt().$this->plainCertificate->getKey().$this->plainCertificate->getCaBundle();
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function getPlain() : self
+    {
+        return $this;
+    }
+
+    /**
+     * Get the crt.
+     *
+     * @return string The crt.
+     */
+    public function getCrt() : ?string
+    {
+        return $this->crt;
+    }
+
+    /**
+     * Set the crt.
+     *
+     * @param string $crt The crt to set
+     *
+     * @return $this The current instance of this class.
+     */
+    public function setCrt(string $crt) : self
+    {
+        $this->crt = $crt;
+
+        return $this;
+    }
+
+    /**
+     * Get the key.
+     *
+     * @return string The key.
+     */
+    public function getKey() : ?string
+    {
+        return $this->key;
+    }
+
+    /**
+     * Set the key.
+     *
+     * @param string $key The key.
+     *
+     * @return $this The current instance of this class.
+     */
+    public function setKey(string $key) : self
+    {
+        $this->key = $key;
+
+        return $this;
+    }
+
+    /**
+     * Get the CA bundle.
+     *
+     * @return string The CA bundle.
+     */
+    public function getCaBundle() : ?string
+    {
+        return $this->caBundle;
+    }
+
+    /**
+     * Set the CA bundle.
+     *
+     * @param string $caBundle The CA bundle.
+     *
+     * @return $this The current instance of this class.
+     */
+    public function setCaBundle(string $caBundle) : self
+    {
+        $this->caBundle = $caBundle;
+
+        return $this;
+    }
+}