diff --git a/src/Build/OfficialPhpSource.php b/src/Build/OfficialPhpSource.php
index ec42014c..cb19bb00 100644
--- a/src/Build/OfficialPhpSource.php
+++ b/src/Build/OfficialPhpSource.php
@@ -2,17 +2,22 @@
 
 namespace TypePhp\Build;
 
+use TypePhp\Http\Downloader;
+
 final class OfficialPhpSource
 {
     private const string RELEASE_API = 'https://www.php.net/releases/index.php?json=1&version=%s&max=100';
     private readonly \Closure $output;
+    private readonly Downloader $downloader;
 
     /** @param callable(string):void $output */
     public function __construct(
         private readonly string $cacheDirectory,
         callable $output,
+        ?string $proxy = null,
     ) {
         $this->output = \Closure::fromCallable($output);
+        $this->downloader = new Downloader($proxy);
     }
 
     public static function defaultCacheDirectory(?string $home = null): string
@@ -82,7 +87,7 @@ final class OfficialPhpSource
         }
 
         $data = json_decode(
-            $this->downloadText(sprintf(self::RELEASE_API, rawurlencode($branch))),
+            $this->downloader->downloadText(sprintf(self::RELEASE_API, rawurlencode($branch))),
             true,
             flags: JSON_THROW_ON_ERROR,
         );
@@ -131,7 +136,7 @@ final class OfficialPhpSource
             ($this->output)('Downloading PHP ' . $release['version'] . ' source from php.net');
             $temporary = $archive . '.part-' . bin2hex(random_bytes(6));
             try {
-                $this->downloadFile($release['url'], $temporary);
+                $this->downloader->downloadFile($release['url'], $temporary);
                 if (hash_file('sha256', $temporary) !== $release['sha256']) {
                     throw new \RuntimeException('PHP source archive SHA-256 verification failed');
                 }
@@ -176,33 +181,6 @@ final class OfficialPhpSource
         return $match[1];
     }
 
-    private function downloadText(string $url): string
-    {
-        $context = stream_context_create(['http' => ['timeout' => 30, 'user_agent' => 'TypePHP/tpc']]);
-        $contents = @file_get_contents($url, false, $context);
-        if (is_string($contents)) {
-            return $contents;
-        }
-        $curl = trim((string) shell_exec('command -v curl 2>/dev/null'));
-        if ($curl === '') {
-            throw new \RuntimeException("Unable to download {$url}; enable allow_url_fopen or install curl");
-        }
-        return $this->capture([$curl, '--fail', '--location', '--retry', '3', $url]);
-    }
-
-    private function downloadFile(string $url, string $target): void
-    {
-        $curl = trim((string) shell_exec('command -v curl 2>/dev/null'));
-        if ($curl !== '') {
-            $this->run([$curl, '--fail', '--location', '--retry', '3', '--output', $target, $url]);
-            return;
-        }
-        $contents = $this->downloadText($url);
-        if (file_put_contents($target, $contents) === false) {
-            throw new \RuntimeException("Unable to write {$target}");
-        }
-    }
-
     /** @param list<string> $command */
     private function run(array $command): void
     {
@@ -212,23 +190,6 @@ final class OfficialPhpSource
         }
     }
 
-    /** @param list<string> $command */
-    private function capture(array $command): string
-    {
-        $process = proc_open($command, [1 => ['pipe', 'w'], 2 => ['pipe', 'w']], $pipes);
-        if (!is_resource($process)) {
-            throw new \RuntimeException('Unable to run command: ' . implode(' ', $command));
-        }
-        $stdout = stream_get_contents($pipes[1]);
-        $stderr = stream_get_contents($pipes[2]);
-        fclose($pipes[1]);
-        fclose($pipes[2]);
-        if (proc_close($process) !== 0) {
-            throw new \RuntimeException(trim($stderr));
-        }
-        return $stdout;
-    }
-
     private function mkdir(string $directory): void
     {
         if (!is_dir($directory) && !mkdir($directory, 0777, true) && !is_dir($directory)) {
diff --git a/src/Build/SapiExtensionRequirements.php b/src/Build/SapiExtensionRequirements.php
index 9ada9329..a30aa65d 100644
--- a/src/Build/SapiExtensionRequirements.php
+++ b/src/Build/SapiExtensionRequirements.php
@@ -44,14 +44,14 @@ final class SapiExtensionRequirements
             }
         }
         $extensions = [];
-        foreach (array_keys($manifests) as $manifest) {
-            $decoded = json_decode((string) file_get_contents($manifest), true);
+        foreach (array_keys($manifests) as $manifestPath) {
+            $decoded = json_decode((string) file_get_contents($manifestPath), true);
             if (!is_array($decoded)) {
-                throw new \RuntimeException("Invalid Composer manifest: {$manifest}");
+                throw new \RuntimeException("Invalid Composer manifest: {$manifestPath}");
             }
             $require = $decoded['require'] ?? [];
             if (!is_array($require)) {
-                throw new \RuntimeException("Composer `require` must be an object: {$manifest}");
+                throw new \RuntimeException("Composer `require` must be an object: {$manifestPath}");
             }
             foreach (array_keys($require) as $package) {
                 if (is_string($package) && str_starts_with(strtolower($package), 'ext-')) {
diff --git a/src/Build/SapiPhpBuilder.php b/src/Build/SapiPhpBuilder.php
index 77f3eb9e..ed42549f 100644
--- a/src/Build/SapiPhpBuilder.php
+++ b/src/Build/SapiPhpBuilder.php
@@ -18,6 +18,7 @@ final class SapiPhpBuilder
     public function __construct(
         private readonly string $phpxSourceDirectory,
         callable $output,
+        private readonly ?string $proxy = null,
     ) {
         $this->output = \Closure::fromCallable($output);
     }
@@ -41,6 +42,7 @@ final class SapiPhpBuilder
         $source = (new OfficialPhpSource(
             OfficialPhpSource::defaultCacheDirectory(),
             $this->output,
+            $this->proxy,
         ))->prepare($phpVersion);
         $sourceVersion = OfficialPhpSource::version($source);
         $baseOptions = $this->sourceConfigureOptions($source);
diff --git a/src/Build/SourcePipelineTrait.php b/src/Build/SourcePipelineTrait.php
index 07404c93..16bdac2a 100644
--- a/src/Build/SourcePipelineTrait.php
+++ b/src/Build/SourcePipelineTrait.php
@@ -583,7 +583,7 @@ trait SourcePipelineTrait
         $phpDir = $this->getPhpDir();
         if ($this->isBuildModeEmbed() && $platform instanceof Linux) {
             try {
-                $phpDir = (new LibPhpInstaller())->ensure($phpDir) ?? $phpDir;
+                $phpDir = (new LibPhpInstaller(proxy: $this->downloadProxy))->ensure($phpDir) ?? $phpDir;
             } catch (\Throwable $e) {
                 $this->error('Unable to install libphp.so: ' . $e->getMessage());
             }
@@ -665,6 +665,7 @@ trait SourcePipelineTrait
             $runtime = (new SapiPhpBuilder(
                 $this->getPhpxDir(),
                 fn (string $message) => $this->output($message, 'lightBlue'),
+                $this->downloadProxy,
             ))->prepare(
                 $this->phpVersion,
                 $this->sapiTargets,
diff --git a/src/CompilerBase.php b/src/CompilerBase.php
index bcf0b634..7fec8c31 100644
--- a/src/CompilerBase.php
+++ b/src/CompilerBase.php
@@ -690,6 +690,7 @@ class CompilerBase implements PropertyAccessContext
     protected array $externalImportStubFiles = [];
     protected bool $enableProfiler = false;
     protected bool $noProgress = false;
+    protected ?string $downloadProxy = null;
     protected bool $forTest = false;
     protected Parser $parser;
     protected ?AstCache $astCache = null;
diff --git a/src/Http/Downloader.php b/src/Http/Downloader.php
new file mode 100644
index 00000000..0cd270d8
--- /dev/null
+++ b/src/Http/Downloader.php
@@ -0,0 +1,146 @@
+<?php
+
+namespace TypePhp\Http;
+
+final class Downloader
+{
+    private readonly ?string $proxy;
+
+    public function __construct(?string $proxy = null)
+    {
+        $proxy = $proxy === null ? null : trim($proxy);
+        if ($proxy === '') {
+            throw new \InvalidArgumentException('Proxy URL must not be empty');
+        }
+        $this->proxy = $proxy;
+    }
+
+    public function downloadText(string $url): string
+    {
+        $curl = $this->findCurl();
+        // curl has consistent support for HTTP(S) and SOCKS proxies. Keep the
+        // existing stream-first path when no explicit proxy was requested.
+        if ($this->proxy !== null && $curl !== null) {
+            return $this->capture($this->curlCommand($curl, $url));
+        }
+
+        $context = stream_context_create($this->streamContextOptions());
+        $contents = @file_get_contents($url, false, $context);
+        if (is_string($contents)) {
+            return $contents;
+        }
+        if ($curl === null) {
+            throw new \RuntimeException("Unable to download {$url}; enable allow_url_fopen or install curl");
+        }
+        return $this->capture($this->curlCommand($curl, $url));
+    }
+
+    public function downloadFile(string $url, string $target): void
+    {
+        $curl = $this->findCurl();
+        if ($curl !== null) {
+            $this->run($this->curlCommand($curl, $url, $target));
+            return;
+        }
+        $contents = $this->downloadText($url);
+        if (file_put_contents($target, $contents) === false) {
+            throw new \RuntimeException("Unable to write {$target}");
+        }
+    }
+
+    /** @return array{http: array<string, int|string|bool>} */
+    public function streamContextOptions(): array
+    {
+        $options = [
+            'timeout' => 30,
+            'user_agent' => 'TypePHP/tpc',
+        ];
+        if ($this->proxy !== null) {
+            [$proxy, $authorization] = $this->streamProxy();
+            $options['proxy'] = $proxy;
+            $options['request_fulluri'] = true;
+            if ($authorization !== null) {
+                $options['header'] = 'Proxy-Authorization: Basic ' . $authorization;
+            }
+        }
+        return ['http' => $options];
+    }
+
+    /** @return list<string> */
+    public function curlCommand(string $curl, string $url, ?string $target = null): array
+    {
+        $command = [$curl, '--fail', '--location', '--retry', '3'];
+        if ($this->proxy !== null) {
+            $command[] = '--proxy';
+            $command[] = $this->proxy;
+        }
+        if ($target !== null) {
+            $command[] = '--output';
+            $command[] = $target;
+        }
+        $command[] = $url;
+        return $command;
+    }
+
+    /** @return array{string, string|null} */
+    private function streamProxy(): array
+    {
+        $proxy = $this->proxy;
+        if (!str_contains($proxy, '://')) {
+            $proxy = 'http://' . $proxy;
+        }
+        $parts = parse_url($proxy);
+        $scheme = strtolower((string) ($parts['scheme'] ?? ''));
+        $host = (string) ($parts['host'] ?? '');
+        if (!in_array($scheme, ['http', 'tcp'], true) || $host === '') {
+            throw new \RuntimeException(
+                "Proxy {$this->proxy} requires curl; the PHP stream fallback supports only HTTP proxies",
+            );
+        }
+        $port = (int) ($parts['port'] ?? 80);
+        $connectionHost = str_contains($host, ':') ? '[' . $host . ']' : $host;
+        $authorization = null;
+        if (isset($parts['user'])) {
+            $authorization = base64_encode(
+                rawurldecode((string) $parts['user']) . ':' . rawurldecode((string) ($parts['pass'] ?? '')),
+            );
+        }
+        return ["tcp://{$connectionHost}:{$port}", $authorization];
+    }
+
+    private function findCurl(): ?string
+    {
+        $command = PHP_OS_FAMILY === 'Windows' ? 'where curl 2>NUL' : 'command -v curl 2>/dev/null';
+        $output = trim((string) shell_exec($command));
+        if ($output === '') {
+            return null;
+        }
+        return strtok($output, "\r\n") ?: null;
+    }
+
+    /** @param list<string> $command */
+    private function run(array $command): void
+    {
+        $process = proc_open($command, [STDIN, STDOUT, STDERR], $pipes);
+        if (!is_resource($process) || proc_close($process) !== 0) {
+            throw new \RuntimeException('Command failed: ' . implode(' ', $command));
+        }
+    }
+
+    /** @param list<string> $command */
+    private function capture(array $command): string
+    {
+        $process = proc_open($command, [1 => ['pipe', 'w'], 2 => ['pipe', 'w']], $pipes);
+        if (!is_resource($process)) {
+            throw new \RuntimeException('Unable to run command: ' . implode(' ', $command));
+        }
+        $stdout = stream_get_contents($pipes[1]);
+        $stderr = stream_get_contents($pipes[2]);
+        fclose($pipes[1]);
+        fclose($pipes[2]);
+        if (proc_close($process) !== 0) {
+            throw new \RuntimeException(trim($stderr));
+        }
+        return $stdout;
+    }
+}
diff --git a/src/Installer/LibPhpInstaller.php b/src/Installer/LibPhpInstaller.php
index 5bfda3a9..f9fd9196 100644
--- a/src/Installer/LibPhpInstaller.php
+++ b/src/Installer/LibPhpInstaller.php
@@ -2,15 +2,20 @@
 
 namespace TypePhp\Installer;
 
+use TypePhp\Http\Downloader;
 use TypePhp\Platform\Linux;
 
 final class LibPhpInstaller
 {
     private const string RELEASE_API = 'https://www.php.net/releases/index.php?json=1&version=%s&max=100';
     private ?string $sourcePhpDir = null;
+    private readonly Downloader $downloader;
 
-    public function __construct(private readonly InteractiveConsole $console = new InteractiveConsole())
-    {
+    public function __construct(
+        private readonly InteractiveConsole $console = new InteractiveConsole(),
+        ?string $proxy = null,
+    ) {
+        $this->downloader = new Downloader($proxy);
     }
 
     public function ensure(string $currentPhpDir): ?string
@@ -119,7 +124,7 @@ final class LibPhpInstaller
 
     private function fetchReleaseList(string $branch): array
     {
-        $json = $this->downloadText(sprintf(self::RELEASE_API, rawurlencode($branch)));
+        $json = $this->downloader->downloadText(sprintf(self::RELEASE_API, rawurlencode($branch)));
         $data = json_decode($json, true, flags: JSON_THROW_ON_ERROR);
         if (!is_array($data)) {
             throw new \RuntimeException('Invalid release list returned by PHP.net');
@@ -173,7 +178,7 @@ final class LibPhpInstaller
 
         if (!is_file($archive) || hash_file('sha256', $archive) !== $release['sha256']) {
             $this->console->write('Downloading ' . $release['url']);
-            $this->downloadFile($release['url'], $archive);
+            $this->downloader->downloadFile($release['url'], $archive);
         }
         if (hash_file('sha256', $archive) !== $release['sha256']) {
             throw new \RuntimeException('PHP source archive SHA-256 verification failed');
@@ -322,33 +327,6 @@ final class LibPhpInstaller
         return null;
     }
 
-    private function downloadText(string $url): string
-    {
-        $context = stream_context_create(['http' => ['timeout' => 30, 'user_agent' => 'TypePHP/tpc']]);
-        $data = @file_get_contents($url, false, $context);
-        if ($data === false) {
-            $curl = trim((string) shell_exec('command -v curl 2>/dev/null'));
-            if ($curl !== '') {
-                return $this->capture([$curl, '--fail', '--location', '--retry', '3', $url]);
-            }
-            throw new \RuntimeException("Unable to download {$url}; enable allow_url_fopen or install curl");
-        }
-        return $data;
-    }
-
-    private function downloadFile(string $url, string $target): void
-    {
-        $curl = trim((string) shell_exec('command -v curl 2>/dev/null'));
-        if ($curl !== '') {
-            $this->run([$curl, '--fail', '--location', '--retry', '3', '--output', $target, $url]);
-            return;
-        }
-        $data = $this->downloadText($url);
-        if (file_put_contents($target, $data) === false) {
-            throw new \RuntimeException("Unable to write {$target}");
-        }
-    }
-
     private function run(array $command, ?string $cwd = null): void
     {
         $this->console->write('$ ' . implode(' ', array_map('escapeshellarg', $command)));
diff --git a/src/Metadata/Constants.php b/src/Metadata/Constants.php
index 45517c33..e5c70fb0 100644
--- a/src/Metadata/Constants.php
+++ b/src/Metadata/Constants.php
@@ -177,6 +177,11 @@ class Constants
             'description' => 'PHP language version to accept (8.4 or 8.5; default: 8.5)',
             'required' => false,
         ],
+        'proxy' => [
+            'longPrefix' => 'proxy',
+            'description' => 'Proxy URL used for file downloads (HTTP(S) or SOCKS)',
+            'required' => false,
+        ],
         'force' => [
             'prefix' => 'f',
             'longPrefix' => 'force',
diff --git a/src/Translator.php b/src/Translator.php
index f8f63f16..9c9ae93b 100644
--- a/src/Translator.php
+++ b/src/Translator.php
@@ -362,6 +362,13 @@ class Translator extends Preprocessor
     {
         $path = null;
         for ($i = 1; $i < count($argv); $i++) {
+            if ($argv[$i] === '--proxy') {
+                ++$i;
+                continue;
+            }
+            if (str_starts_with($argv[$i], '--proxy=')) {
+                continue;
+            }
             if ($argv[$i] !== '' && $argv[$i][0] !== '-') {
                 $path = $argv[$i];
                 break;
@@ -443,6 +450,7 @@ class Translator extends Preprocessor
             ['--lto', 'Enable Link Time Optimization (-flto)'],
             ['--no-literal-strings', 'Disable literal string optimization'],
             ['--php-version <ver>', 'Accepted PHP language version (8.4-8.5, default: 8.5)'],
+            ['--proxy <url>', 'Proxy URL used for file downloads'],
             ['--no-progress', 'Print one compilation line per file instead of a progress bar'],
             ['--no-console', 'Hide the console window (Windows GUI applications only)'],
             ['--sanitize <type>', 'Enable a sanitizer such as address or undefined'],
@@ -473,6 +481,14 @@ class Translator extends Preprocessor
     {
         $this->applyPhpVersionCommandLineArgument();
 
+        if ($this->climate->arguments->defined('proxy')) {
+            $proxy = trim((string) $this->climate->arguments->get('proxy'));
+            if ($proxy === '') {
+                $this->error('Option --proxy requires a non-empty URL');
+            }
+            $this->downloadProxy = $proxy;
+        }
+
         // The Nano syntax policy is platform-independent. On non-Windows hosts
         // only the runtime source and link inputs change; argument parsing,
         // translation, compilation scheduling and diagnostics remain shared.