diff --git a/src/Calco2latoApiClient.php b/src/Calco2latoApiClient.php
index e69de29..3a5d3b7 100644
--- a/src/Calco2latoApiClient.php
+++ b/src/Calco2latoApiClient.php
@@ -0,0 +1,103 @@
+<?php
+declare(strict_types=1);
+
+final class Calco2latoApiClient
+{
+    private string $baseUrl;
+    private string $apiKey;
+    private int $timeout;
+
+    public function __construct(string $baseUrl, string $apiKey, int $timeoutSeconds = 10)
+    {
+        $this->baseUrl = rtrim($baseUrl, '/');
+        $this->apiKey  = $apiKey;
+        $this->timeout = $timeoutSeconds;
+    }
+
+    /**
+     * Low-level request wrapper (GET/POST/DELETE/PUT/PATCH).
+     * $query is appended to URL; $body (if provided) is JSON-encoded.
+     */
+    private function request(string $method, string $path, array $query = [], ?array $body = null): array
+    {
+        $url = $this->baseUrl . '/' . ltrim($path, '/');
+        if (!empty($query)) {
+            $url .= (str_contains($url, '?') ? '&' : '?') . http_build_query($query);
+        }
+
+        $ch = curl_init($url);
+        $headers = [
+            'Accept: application/json',
+            'Authorization: Bearer ' . $this->apiKey,
+        ];
+        curl_setopt_array($ch, [
+            CURLOPT_RETURNTRANSFER => true,
+            CURLOPT_CUSTOMREQUEST  => strtoupper($method),
+            CURLOPT_HTTPHEADER     => $headers,
+            CURLOPT_TIMEOUT        => $this->timeout,
+        ]);
+
+        if ($body !== null) {
+            $json = json_encode($body, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
+            $headers[] = 'Content-Type: application/json';
+            curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
+            curl_setopt($ch, CURLOPT_POSTFIELDS, $json);
+        }
+
+        $responseBody = curl_exec($ch);
+        $status       = curl_getinfo($ch, CURLINFO_HTTP_CODE);
+        $err          = curl_error($ch);
+        curl_close($ch);
+
+        if ($responseBody === false) {
+            throw new RuntimeException('cURL error: ' . $err);
+        }
+
+        $decoded = json_decode($responseBody, true);
+        if ($decoded === null && json_last_error() !== JSON_ERROR_NONE) {
+            throw new RuntimeException('Invalid JSON from API (HTTP ' . $status . '): ' . $responseBody);
+        }
+
+        if ($status < 200 || $status >= 300) {
+            $msg = $decoded['error'] ?? $decoded['message'] ?? 'Upstream API error';
+            throw new RuntimeException('API error (HTTP ' . $status . '): ' . $msg);
+        }
+
+        return $decoded;
+    }
+
+    // ---------- Airports ----------
+
+    /** Search airports by free-text (IATA/ICAO/name/city/country) */
+    public function searchAirports(string $q, int $limit = 20, int $offset = 0): array
+    {
+        return $this->request('GET', '/api/latest/airports/search', [
+            'q' => $q,
+            'limit' => $limit,
+            'offset' => $offset,
+        ]);
+    }
+
+    /** Get a single airport by IATA or ICAO code */
+    public function getAirport(string $code): array
+    {
+        return $this->request('GET', '/api/latest/airports/' . urlencode($code));
+    }
+
+    // ---------- Flights ----------
+
+    /**
+     * Get flight estimate / emissions (example – adjust to your API)
+     * $params might include origin, destination, date, pax, class, etc.
+     */
+    public function flightEstimate(array $params): array
+    {
+        return $this->request('POST', '/api/latest/flights/estimate', [], $params);
+    }
+
+    /** Optional: resolve a route or fetch a published flight record */
+    public function getFlightById(string $id): array
+    {
+        return $this->request('GET', '/api/latest/flights/' . urlencode($id));
+    }
+}