You need to ship a reliable currency conversion feature in PHP this week—for payouts, checkout totals, or financial reporting—and you want one API key and a single subscription to keep procurement simple. By the end of this guide, you will know how to use a currency exchange rate API from Zyla API Hub in a production-ready PHP workflow, how to structure your code for caching and fallbacks, and how to invoke the same finance API from an AI agent through Zyla’s MCP bridge.
What you can build with a Currency Exchange Rate API on Zyla API Hub
A currency exchange rate API provides machine-readable exchange rate data that developers use to:
- Convert an amount from a source currency (e.g., USD) to a target currency (e.g., EUR) for checkout or invoicing.
- Display reference rates for multiple currencies in dashboards or statements.
- Normalize historical or intra-day amounts to a single reporting currency.
On Zyla API Hub, finance APIs live behind one account, one API key and one subscription model. This standardization reduces the moving parts you need to manage when you add or swap providers later. Every API on the marketplace can also be called from MCP-compatible developer tools, allowing you to orchestrate calls from AI agents without changing your backend integration.
Getting started on Zyla API Hub
To connect your PHP service to a currency exchange rate API on Zyla:
- Open the API page on Zyla API Hub and review its description to confirm it returns the exchange data you need.
- Click Subscribe or Start Free Trial when available, then copy your API key.
- From the API page, copy the documented endpoint URL(s), HTTP method(s), and any required parameters.
Important: Refer to the API page for current access options and pricing. Authentication style and parameter names are defined on that page. This guide does not guess undocumented details.
Endpoint overview and how to read the docs
Since endpoint names, methods, URLs, required parameters, and response fields are defined per API on Zyla, use this checklist when you open the Currency Exchange Rate API page:
- Locate the base URL and the exact path(s) for:
- Fetching latest exchange rates for one or multiple currencies.
- Converting an amount from one currency to another, if provided as a single operation.
- Querying rates for a specific date, if historical data is available.
- Confirm the HTTP method for each endpoint (commonly GET, sometimes POST for conversions).
- List required parameters:
- Base or source currency code (e.g., “USD”).
- Target currency code(s) (e.g., “EUR,GBP,JPY”).
- Amount to convert (if the API offers a conversion endpoint).
- Date (if historical queries are supported).
- Identify response fields used in your app (e.g., the numeric exchange rate and any timestamp or base currency indicators).
If a specific field or parameter is not listed on the API page, do not assume it exists—implement only what the documentation explicitly defines.
PHP integration patterns for finance-grade reliability
Below is a PHP structure you can adapt once you paste the exact endpoint and parameters from the API’s page. It emphasizes predictable error handling, caching, and data validation—core requirements in finance integrations.
Core PHP flow
This flow assumes a “latest rates” or “convert” style endpoint exists. You will fill in the URL, method, headers, and parameter names exactly as documented on the API page.
<?php
declare(strict_types=1);
/**
* Currency conversion service using a Zyla-hosted finance API.
* 1. Read API key from environment or secrets manager.
* 2. Build the request from documented endpoint and parameters.
* 3. Add a minimal cache to avoid re-fetching identical data within a short TTL.
* 4. Parse and validate numeric fields before computations.
*/
final class FxClient
{
private string $apiKey;
private string $endpoint; // Paste the exact endpoint URL from the Zyla API page
private int $ttlSeconds = 300; // Cache time window; adjust to your business needs
public function __construct(string $apiKey, string $endpoint)
{
$this->apiKey = $apiKey;
$this->endpoint = $endpoint;
}
public function convert(string $from, string $to, float $amount, ?string $date = null): array
{
// Build query based on the API’s documented parameters.
// Replace 'from', 'to', 'amount', 'date' keys below with the real parameter names if they differ.
$query = [
'from' => $from,
'to' => $to,
'amount' => $amount,
];
if ($date !== null) {
$query['date'] = $date;
}
$cacheKey = $this->cacheKey($query);
$cached = $this->cacheGet($cacheKey);
if ($cached !== null) {
return $cached;
}
$url = $this->endpoint . '?' . http_build_query($query);
// Set headers exactly as documented on the API page.
// If the API uses header-based auth, add it below.
$headers = [
// Example (replace with the real header name if different):
// 'Authorization: Bearer ' . $this->apiKey,
// or 'X-API-KEY: ' . $this->apiKey
];
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
if (!empty($headers)) {
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
}
$response = curl_exec($ch);
if ($response === false) {
$err = curl_error($ch);
curl_close($ch);
throw new RuntimeException('FX API request failed: ' . $err);
}
$status = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);
if ($status < 200 || $status >= 300) {
throw new RuntimeException('FX API HTTP ' . $status . ' — body: ' . $response);
}
$data = json_decode($response, true, flags: JSON_BIGINT_AS_STRING);
if (!is_array($data)) {
throw new RuntimeException('FX API returned non-JSON or invalid JSON');
}
// Validate documented fields before returning.
// Adjust checks to match the exact response structure from the API page.
// For example, ensure "rate" or "result" is numeric.
// if (!isset($data['rate']) || !is_numeric($data['rate'])) { ... }
$this->cacheSet($cacheKey, $data, $this->ttlSeconds);
return $data;
}
private function cacheKey(array $query): string
{
return 'fx:' . hash('sha256', json_encode($query));
}
private function cacheGet(string $key): ?array
{
$path = sys_get_temp_dir() . DIRECTORY_SEPARATOR . $key . '.json';
if (!file_exists($path)) {
return null;
}
$mtime = filemtime($path);
if ($mtime === false || (time() - $mtime) > $this->ttlSeconds) {
@unlink($path);
return null;
}
$json = file_get_contents($path);
if ($json === false) {
return null;
}
$data = json_decode($json, true);
return is_array($data) ? $data : null;
}
private function cacheSet(string $key, array $value, int $ttl): void
{
$path = sys_get_temp_dir() . DIRECTORY_SEPARATOR . $key . '.json';
file_put_contents($path, json_encode($value));
touch($path, time()); // refresh mtime
}
}
// Usage
$apiKey = getenv('ZYLA_API_KEY') ?: '';
$endpoint = getenv('ZYLA_FX_ENDPOINT') ?: ''; // Paste the exact endpoint from the API page
if ($apiKey === '' || $endpoint === '') {
throw new RuntimeException('Missing ZYLA_API_KEY or ZYLA_FX_ENDPOINT');
}
$client = new FxClient($apiKey, $endpoint);
// Example:
// $result = $client->convert('USD', 'EUR', 123.45);
// var_dump($result);
Replace the endpoint, headers, and parameter names with those specified on the API page. Keep the numeric validations strict; in finance workflows, fail fast on non-numeric or missing fields.
Production details that save hours
- Base currency and symbols: Check whether the API expresses rates as “target per base” (e.g., EUR per USD). Always read the base currency field in the response before computing amounts.
- Timestamps and timezone: Finance data often carries timestamps. Normalize to UTC internally, and store the returned timestamp alongside the rate you used for auditability.
- Caching strategy: Cache the same request for a short time window (e.g., 1–10 minutes) unless the API’s documentation specifies stricter recency requirements. Cache by a key that includes base, symbols, and date.
- Non-trading days: If the API serves official reference rates, weekend or holiday updates may not occur. Decide how your UI or pricing logic behaves when the timestamp is older than your threshold.
- Rounding: For display, round to 2–4 decimals depending on currency pair norms. For accounting, store full precision from the API response and round only at presentation or posting time based on your ledger rules.
Calling from AI agents via the MCP bridge
Every API on Zyla can be invoked through the MCP bridge endpoint. This is useful if you are orchestrating finance workflows in tools like Claude Code, Cursor, or Windsurf and want the agent to call the same subscribed API without embedding new credentials.
The MCP gateway URL is:
https://mcp.zylalabs.com/mcp?apikey=YOUR_API_KEYTooling-specific invocation details (e.g., request body shape, tool registration) depend on your MCP client. See the bridge documentation here: MCP. Use the exact finance API name and parameters as documented on the API’s page when registering or prompting the agent.
cURL and JavaScript examples you will adapt after copying the endpoint
Once you have the exact endpoint URL and required parameters from the API page, your CLI and application code become straightforward. Below are template examples to fill in with those specifics. Do not change parameter names or headers unless they match the API page.
cURL template (fill with the exact URL, method, and headers from the API page)
# Replace METHOD, ENDPOINT_URL, query parameters, and headers with the values shown on the API page.
# Do not change parameter names unless the page documents different names.
curl -X METHOD \
"ENDPOINT_URL?from=USD&to=EUR&amount=123.45" \
-H "YOUR-AUTH-HEADER: YOUR_API_KEY"
Note: This is a template. The exact method, URL, header name, and parameter keys come from the API page you subscribed to.
JavaScript (Node.js, fetch) template
import fetch from 'node-fetch';
async function convert() {
const apiKey = process.env.ZYLA_API_KEY;
const endpoint = process.env.ZYLA_FX_ENDPOINT; // Paste the exact endpoint URL
const params = new URLSearchParams({
// Replace keys as documented by the API page:
from: 'USD',
to: 'EUR',
amount: '123.45'
});
const url = `${endpoint}?${params.toString()}`;
const res = await fetch(url, {
method: 'GET', // Replace with the documented method if different
headers: {
// Replace with the documented header name, if any (e.g., 'Authorization' or 'X-API-KEY')
// 'Authorization': `Bearer ${apiKey}`
}
});
if (!res.ok) {
const text = await res.text();
throw new Error(`HTTP ${res.status}: ${text}`);
}
const data = await res.json();
// Validate documented fields before using them:
// e.g., if (typeof data.rate !== 'number') throw new Error('Invalid rate');
return data;
}
convert()
.then(data => console.log(data))
.catch(err => {
console.error(err);
process.exit(1);
});
Replace the method, header name, and parameter keys with what the API documentation explicitly states. If the response contains a numeric rate and a timestamp, read and validate both before performing calculations or rendering UI.
Real-world finance use cases you can ship this week
- E-commerce checkout: Convert the shopping cart total from a store currency to the shopper’s preferred currency. Cache the rate for the session to ensure totals don’t jump during checkout.
- Payout splits: Normalize creator earnings to a platform’s base currency using the rate at the time of posting, then store the timestamp and rate as immutable metadata.
- Analytics and reporting: Render a multi-currency revenue dashboard by fetching a daily rate (or a documented historical endpoint) and computing a consistent reporting currency.
- Billing and invoicing: Show a customer’s invoice in their local currency while storing the ledger amounts in your base currency using the same rate for both directions.
Testing checklist before going live
- Precision: Confirm the numeric precision and rounding rules for each step (conversion, storage, display).
- Fail-safes: Decide how your app behaves if the API is temporarily unreachable (e.g., return the last cached valid rate with a visible “as of” timestamp).
- Idempotency: If you post conversion operations, ensure retries do not duplicate external calls unless necessary.
- Observability: Log the base currency, symbols, raw rate, and timestamp used per conversion for reconciliation.
- Timezones: Convert any returned timestamps to UTC before comparing freshness or persisting.
How to proceed now
1) Create your account, subscribe to the finance API you need, and copy your API key. 2) Paste the documented endpoint and parameters into the PHP and JavaScript templates above. 3) Add caching and numeric validations. 4) If you want AI agents to help, wire the same API through the MCP bridge. Start here: Register.
FAQ
Does the API include historical exchange rates?
Check the API page on Zyla for supported endpoints. If a historical endpoint is provided, it will list the date parameter and the response fields.
What authentication header should I use?
Use exactly the authentication mechanism documented on the API page (header name and format or query parameter). Do not assume a default scheme.
How often should I refresh rates in production?
Use a short TTL (e.g., a few minutes) unless the API documentation specifies different update intervals. Always store the returned timestamp to prove which rate you used.
Can I call the same finance API from an AI agent?
Yes. Use the MCP bridge at the documented URL and follow your MCP client’s instructions for tool invocation. Reference the exact API name and parameters from the API page.
Is there a free trial?
Check the API page on Zyla for current access options and pricing. Availability can change.
