Top Payment Processing APIs in 2025

In the rapidly evolving world of technology, APIs (Application Programming Interfaces) have become essential tools for developers, enabling seamless integration and functionality across various applications. This blog post will explore the top 10 APIs in the realm of financial services, focusing on their features, capabilities, and practical applications. Each API will be discussed in detail, providing developers with the insights needed to implement them effectively in their projects.

1. SSL Certificate Checker API

The SSL Certificate Checker API is a vital tool for verifying and validating SSL certificates on websites. This API provides extensive information about the SSL certificates present on a given website, ensuring that users can assess the security of their online interactions.

One of the key features of this API is the Check capability, which allows developers to check the validity of an SSL certificate. When a URL is passed to the API, it returns detailed information about the certificate, including the issuer, validity dates, and expiration status. This feature is particularly useful for security companies and developers who want to ensure that their websites are safe for users.

{
  "subject": {
    "jurisdictionC": "US",
    "jurisdictionST": "Delaware",
    "businessCategory": "Private Organization",
    "serialNumber": "3014267",
    "C": "US",
    "ST": "California",
    "L": "San Jose",
    "O": "PayPal, Inc.",
    "CN": "www.paypal.com"
  },
  "issuer": {
    "C": "US",
    "O": "DigiCert Inc",
    "OU": "www.digicert.com",
    "CN": "DigiCert SHA2 Extended Validation Server CA"
  },
  "validFrom": "2024-06-13T00:00:00.000Z",
  "validTo": "2025-06-12T23:59:59.000Z",
  "expiresInDays": 215,
  "fingerprint": "B8:52:A5:56:6A:3C:F4:6B:0F:90:23:FA:3E:26:C8:8B:BA:55:D3:C9",
  "protocol": "TLSv1.3",
  "cipher": {
    "name": "TLS_AES_256_GCM_SHA384",
    "standardName": "TLS_AES_256_GCM_SHA384",
    "version": "TLSv1.3"
  }
}

In this response, the subject field contains information about the organization that owns the certificate, while the issuer field provides details about the certificate authority. The validFrom and validTo fields indicate the certificate's validity period, and the fingerprint is used for certificate identification. Developers can use this data to programmatically assess the security of websites and ensure compliance with security standards.

2. Routing Bank Number Checker API

The Routing Bank Number Checker API is an essential tool for validating bank routing numbers. This API checks the validity of routing numbers entered, ensuring that they belong to legitimate banks. It is particularly useful for financial institutions and businesses that handle financial transactions.

One of the primary features of this API is the Routing Number Lookup, which returns information about a bank by passing in the routing number. When a routing number is provided, the API verifies its validity and returns relevant data, including the bank's name, address, and contact details.

{
  "status": 200,
  "success": true,
  "message": "Routing Bank 053100465 is valid",
  "data": {
    "routing_number": "053100465",
    "date_of_revision": "080714",
    "bank": "SUNTRUST",
    "address": "FL-ORL-7150",
    "city": "ORLANDO",
    "state": "FL",
    "zip": "32809",
    "phone": "(800) 221-9792"
  }
}

The response includes a status field indicating the success of the request, and the data object contains detailed information about the bank associated with the routing number. Developers can use this information to verify the legitimacy of bank accounts before processing payments, thus minimizing the risk of errors and fraud.

3. Invoice Generator API

The Invoice Generator API simplifies the process of generating professional-looking invoices in PDF format. This API is particularly beneficial for businesses and individuals looking to automate their invoicing process, reducing the time and effort required to create invoices manually.

One of the key features of this API is the Invoice Generator, which allows users to quickly generate invoices through a REST API endpoint. By passing the necessary invoice details, users can receive a PDF invoice in return.

{
  "success": true,
  "url": "https://billtime.io/storage/invoice_INVOICE01_.67b60e680fe25.pdf"
}

The response indicates whether the invoice generation was successful and provides a url field containing the link to the generated PDF invoice. This feature is invaluable for e-commerce platforms, freelancers, and small businesses, as it streamlines the invoicing process and helps ensure timely payments.

4. Card Guardian API

The Card Guardian API is designed to enhance credit card data security by securely hiding credit card numbers. This API is crucial for applications that handle sensitive payment information, ensuring user privacy and compliance with data protection regulations.

One of the main features of this API is the Security Card capability, which allows developers to mask credit card numbers by hiding certain characters. By integrating this API, developers can ensure that credit card numbers are only displayed to authorized users in a secure manner.

{
  "_call_id": "320Q-s6baO",
  "call_response": {
    "models_applied": ["Sensitive"],
    "input": {
      "text": "credit card num 5555555555554444"
    },
    "result": {
      "clean": "credit card num XXXXXXXXXXXXXXXX",
      "additional": {}
    },
    "input_hash": "691f5ea62fcedf891ce4553d1de53c7f77779929"
  },
  "_api_name": "cleanText",
  "_api_version": "0.0.1",
  "_call_time": "2023-06-06T16:04:50.652Z"
}

The response includes a _call_id for tracking the API call, the input field showing the original text, and the result field containing the masked output. This feature is particularly useful for payment processors and e-commerce platforms, as it helps protect sensitive customer data during transactions.

5. Textify Money API

The Textify Money API provides a simplified method for converting numeric representations into text values. This API is valuable for applications that require the conversion of monetary values into a human-readable format.

One of the primary features of this API is the Get Textify capability, which allows users to convert numeric values into their corresponding text representations by specifying the number and language.

{
  "success": true,
  "message": "The getTextFromNumber was successfully completed!",
  "data": "einhundert"
}

The response indicates the success of the conversion and provides the data field containing the text representation of the input number. This feature is particularly useful for billing systems and financial applications, as it enhances the clarity and professionalism of financial documents.

6. International Currency API

The International Currency API simplifies cross-border transactions by offering real-time and accurate exchange rate calculations. This API is essential for businesses and individuals engaged in international trade and travel.

One of the key features of this API is the Get Conversion capability, which allows users to convert amounts between different currencies by specifying the source and target currencies along with the amount to convert.

{
  "success": true,
  "code": 0,
  "timestamp": 1690300800,
  "q": {
    "from": "USD",
    "to": ["CHF"],
    "amount": 1
  },
  "result": {
    "CHF": 0.86442
  }
}

The response includes a success field indicating the success of the conversion, a timestamp for the request time, and a result object showing the converted amount. This feature is invaluable for e-commerce platforms and financial applications, as it enables accurate pricing and budgeting in multiple currencies.

7. Card Checker API

The Card Checker API is a powerful tool for validating bank card authenticity, preventing fraud, and ensuring smooth transactions. This API is particularly useful for online merchants and financial institutions.

One of the main features of this API is the Check Card capability, which allows users to enter a six-digit BIN number to validate the authenticity of a bank card.

{
  "status": 200,
  "success": true,
  "isValid": true,
  "message": "The BIN number is valid.",
  "data": {
    "bin_iin": "557829",
    "card_brand": "MASTERCARD",
    "card_type": "CREDIT",
    "issuer_name_bank": "AKBANK T.A.S.",
    "iso_country_name": "TURKEY",
    "iso_country_code": "TR"
  }
}

The response includes a status field indicating the success of the request, an isValid field confirming the validity of the card, and a data object containing details about the card brand, type, and issuing bank. This feature helps businesses minimize the risk of fraudulent transactions and enhance customer trust.

8. Commerce Tax Rates API

The Commerce Tax Rates API provides up-to-date sales tax rates for accurate and compliant transactions in the United States. This API is essential for e-commerce platforms and retailers.

One of the key features of this API is the US Taxes capability, which allows users to enter a US zip code to retrieve the corresponding sales tax rates.

{
  "status": true,
  "message": "",
  "data": {
    "zip_code": 90001,
    "state": "CA",
    "state_rate": "0.06000",
    "county_rate": "0.00250",
    "city_rate": "0.00750",
    "special_rate": "0.03250",
    "city": "Los Angeles"
  }
}

The response includes a status field indicating the success of the request and a data object containing detailed information about the sales tax rates for the specified zip code. This feature is invaluable for ensuring compliance with tax regulations and optimizing pricing strategies.

9. Currency Conversion Engine API

The Currency Conversion Engine API streamlines global transactions by providing real-time rates and accurate conversions. This API is essential for businesses operating in multiple currencies.

One of the primary features of this API is the Currency Conversion capability, which allows users to convert amounts between two specified currencies.

{
  "success": true,
  "message": "OK",
  "date": "2023-09-06",
  "currency": {
    "from": "USD",
    "to": "IDR"
  },
  "result": {
    "raw": 15289.610049,
    "formatted": "15,289.61",
    "currency": "IDR 15,289.61"
  },
  "copyright": "Masiting.dev"
}

The response includes a success field indicating the success of the conversion, a date field for the conversion date, and a result object containing both raw and formatted values for the converted amount. This feature is particularly useful for e-commerce platforms and financial applications, as it enables accurate pricing and budgeting in multiple currencies.

10. Exchange Rate Data API

The Exchange Rate Data API provides real-time rates, historical data, and effortless conversion for global financial transactions. This API is crucial for businesses, travelers, and developers worldwide.

One of the key features of this API is the All Currencies capability, which allows users to retrieve a list of all available currencies.

{
  "success": true,
  "data": {
    "AED": "United Arab Emirates Dirham",
    "AFN": "Afghan Afghani",
    "ALL": "Albanian Lek",
    "AMD": "Armenian Dram",
    "ANG": "Netherlands Antillean Guilder",
    "ARS": "Argentine Peso",
    "AUD": "Australian Dollar",
    "BRL": "Brazilian Real",
    "CAD": "Canadian Dollar",
    "CHF": "Swiss Franc",
    "CNY": "Chinese Yuan",
    "EUR": "Euro",
    "GBP": "British Pound Sterling",
    "INR": "Indian Rupee",
    "JPY": "Japanese Yen",
    "USD": "United States Dollar"
  }
}

The response includes a success field indicating the success of the request and a data object containing a list of all supported currencies and their names. This feature is invaluable for applications that require currency conversion and financial reporting.

Conclusion

In conclusion, the APIs discussed in this blog post provide a wealth of functionality for developers working in the financial services sector. From validating SSL certificates and routing numbers to generating invoices and converting currencies, these APIs offer essential tools for enhancing security, improving user experience, and streamlining financial transactions. By leveraging these APIs, developers can create robust applications that meet the demands of today's digital economy, ensuring compliance, security, and efficiency in their operations.