diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8e8aee24..7e981b8e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # CHANGELOG
 
+## Next Release
+
+- Removes the deprecated, unusable `addCreditCard` function
+  - Stripe has disabled the ability to pass plain credit card details over the wire and now requires using [Stripe.js/Elements/Checkout](https://support.stripe.com/questions/card-tokenization-restrictions-using-publishable-keys). Follow the [Decentralized (EasyPost-Manage Billing) Guide](https://docs.easypost.com/guides/get-started-with-forge/easypost-managed-billing-guide#referralcustomer-billing-management) for more details on the new flow to use.
+  - Makes `referralCustomer.retrieveEasypostStripeApiKey` public to help facilitate adding credit cards using Stripe.js
+
 ## v8.8.3 (2026-08-26)
 
 - Preserves caller-provided plain PHP objects in request params so `(object) []` is sent as an empty JSON object (`{}`) instead of being stringified
diff --git a/lib/EasyPost/Constant/Constants.php b/lib/EasyPost/Constant/Constants.php
index ec7b1023..522c2557 100644
--- a/lib/EasyPost/Constant/Constants.php
+++ b/lib/EasyPost/Constant/Constants.php
@@ -43,7 +43,6 @@ abstract class Constants
 
     const NO_USER_FOUND_ERROR = 'No user found with the given ID.';
     const NO_RESPONSE_ERROR = 'Did not receive a response from %s.';
-    const SEND_STRIPE_DETAILS_ERROR = 'Could not send card details to Stripe, please try again later.';
     const UNDEFINED_PROPERTY_ERROR = 'EasyPost Notice: Undefined property of %s instance: %s';
     const NO_MATCHING_MOCK_REQUEST = 'No matching mock request found for %s %s';
     const END_OF_PAGINATION = 'There are no more pages to retrieve.';
diff --git a/lib/EasyPost/Service/ReferralCustomerService.php b/lib/EasyPost/Service/ReferralCustomerService.php
index 9ff66f32..c8a94993 100644
--- a/lib/EasyPost/Service/ReferralCustomerService.php
+++ b/lib/EasyPost/Service/ReferralCustomerService.php
@@ -3,14 +3,9 @@
 namespace EasyPost\Service;
 
 use EasyPost\Http\HttpMethod;
-use EasyPost\Constant\Constants;
 use EasyPost\EasyPostClient;
-use EasyPost\Exception\Api\ExternalApiException;
-use EasyPost\Exception\Api\HttpException;
-use EasyPost\Exception\Api\TimeoutException;
 use EasyPost\Http\Requestor;
 use EasyPost\Util\InternalUtil;
-use GuzzleHttp\Client;
 
 /**
  * ReferralCustomer service containing all the logic to make API calls.
@@ -71,49 +66,6 @@ public function updateEmail(string $userId, string $email): void
         Requestor::request($this->client, HttpMethod::PUT, "/referral_customers/{$userId}", $wrappedParams);
     }
 
-    /**
-     * Add a credit card to EasyPost for a ReferralCustomer without needing a Stripe account.
-     *
-     * This function requires the Referral User's API key.
-     *
-     * @param string $referralApiKey
-     * @param string $number
-     * @param int $expirationMonth
-     * @param int $expirationYear
-     * @param string $cvc
-     * @param string $priority
-     * @return mixed
-     * @throws ExternalApiException
-     */
-    public function addCreditCard(
-        string $referralApiKey,
-        string $number,
-        int $expirationMonth,
-        int $expirationYear,
-        string $cvc,
-        string $priority = 'primary'
-    ): mixed {
-        $easypostStripeApiKey = self::retrieveEasypostStripeApiKey();
-
-        try {
-            $stripeToken = self::createStripeToken(
-                $number,
-                $expirationMonth,
-                $expirationYear,
-                $cvc,
-                $easypostStripeApiKey
-            );
-        } catch (\Exception $error) {
-            throw new ExternalApiException(Constants::SEND_STRIPE_DETAILS_ERROR);
-        }
-
-        $stripeToken = $stripeToken['id'] ?? '';
-
-        $response = self::createEasypostCreditCard($referralApiKey, $stripeToken, $priority);
-
-        return InternalUtil::convertToEasyPostObject($this->client, $response);
-    }
-
     /**
      * Add a credit card to EasyPost for a ReferralCustomer with a payment method ID from Stripe.
      *
@@ -176,97 +128,10 @@ public function addBankAccountFromStripe(
      *
      * @return string
      */
-    private function retrieveEasypostStripeApiKey(): string
+    public function retrieveEasypostStripeApiKey(): string
     {
         $response = Requestor::request($this->client, HttpMethod::GET, '/partners/stripe_public_key');
 
         return $response['public_key'] ?? '';
     }
-
-    /**
-     * Retrieves the public EasyPost Stripe API key.
-     *
-     * @param string $number
-     * @param int $expirationMonth
-     * @param int $expirationYear
-     * @param string $cvc
-     * @param string $easypostStripeKey
-     * @return mixed
-     * @throws HttpException
-     * @throws TimeoutException
-     */
-    private function createStripeToken(
-        string $number,
-        int $expirationMonth,
-        int $expirationYear,
-        string $cvc,
-        string $easypostStripeKey
-    ): mixed {
-        $headers = [
-            'Content-Type' => 'application/x-www-form-urlencoded',
-            'Authorization' => "Bearer $easypostStripeKey",
-        ];
-
-        $creditCardDetails = [
-            'card' => [
-                'number' => $number,
-                'exp_month' => $expirationMonth,
-                'exp_year' => $expirationYear,
-                'cvc' => $cvc,
-            ]
-        ];
-
-        $url = 'https://api.stripe.com/v1/tokens';
-
-        $guzzleClient = new Client();
-
-        $requestOptions['query'] = $creditCardDetails;
-        $requestOptions['headers'] = $headers;
-        $requestOptions['http_errors'] = false;
-
-        try {
-            $response = $guzzleClient->request(HttpMethod::POST->value, $url, $requestOptions);
-        } catch (\GuzzleHttp\Exception\ConnectException $error) {
-            throw new HttpException(sprintf(Constants::COMMUNICATION_ERROR, 'Stripe', $error->getMessage()));
-        }
-
-        // Guzzle does not have a native way of catching timeout exceptions...
-        // If we don't have a response at this point, it's likely due to a timeout.
-        // @phpstan-ignore-next-line
-        if (!isset($response)) {
-            throw new TimeoutException(sprintf(Constants::NO_RESPONSE_ERROR, 'Stripe'));
-        }
-
-        $responseBody = $response->getBody();
-        $httpStatus = $response->getStatusCode();
-        $response = Requestor::interpretResponse($responseBody, $httpStatus);
-
-        return $response;
-    }
-
-    /**
-     * Submit the Stripe credit card token to EasyPost.
-     *
-     * @param string $referralApiKey
-     * @param string $stripeObjectId
-     * @param string $priority
-     * @return mixed
-     */
-    private function createEasypostCreditCard(
-        string $referralApiKey,
-        string $stripeObjectId,
-        string $priority = 'primary'
-    ): mixed {
-        $params = [
-            'credit_card' => [
-                'stripe_object_id' => $stripeObjectId,
-                'priority' => $priority,
-            ]
-        ];
-
-        $client = new EasyPostClient($referralApiKey);
-        $response = Requestor::request($client, HttpMethod::POST, '/credit_cards', $params);
-
-        return InternalUtil::convertToEasyPostObject($this->client, $response);
-    }
 }
diff --git a/test/EasyPost/ReferralCustomerTest.php b/test/EasyPost/ReferralCustomerTest.php
index e5bd09e8..aa8a3b3a 100644
--- a/test/EasyPost/ReferralCustomerTest.php
+++ b/test/EasyPost/ReferralCustomerTest.php
@@ -116,28 +116,6 @@ public function testUpdateEmail(): void
         }
     }
 
-    /**
-     * Test that we can add a credit card to a referral user.
-     *
-     * This test requires a partner user's production API key via PARTNER_USER_PROD_API_KEY
-     * as well as one of that user's referral's production API keys via REFERRAL_USER_PROD_API_KEY.
-     */
-    public function testAddCreditCard(): void
-    {
-        TestUtil::setupCassette('referral_customers/addCreditCard.yml');
-
-        $creditCard = self::$client->referralCustomer->addCreditCard(
-            self::$referralUserProdApiKey,
-            Fixture::creditCardDetails()['number'],
-            Fixture::creditCardDetails()['expiration_month'],
-            Fixture::creditCardDetails()['expiration_year'],
-            Fixture::creditCardDetails()['cvc']
-        );
-
-        $this->assertStringMatchesFormat('pm_%s', $creditCard->id);
-        $this->assertEquals('6170', $creditCard->last4);
-    }
-
     /**
      * Test that we can add a credit card to a referral user.
      *
@@ -186,4 +164,19 @@ public function testAddBankAccountFromStripe(): void
             );
         }
     }
+
+    /**
+     * Test that we can retrieve EasyPost's Stripe API key.
+     *
+     * This test requires a partner user's production API key via PARTNER_USER_PROD_API_KEY.
+     */
+    public function testRetrieveEasypostStripeApiKey(): void
+    {
+        TestUtil::setupCassette('referral_customers/retrieveEasypostStripeApiKey.yml');
+
+        $publicKey = self::$client->referralCustomer->retrieveEasypostStripeApiKey();
+
+        $this->assertIsString($publicKey);
+        $this->assertStringStartsWith('pk_', $publicKey);
+    }
 }
diff --git a/test/cassettes/referral_customers/addCreditCard.yml b/test/cassettes/referral_customers/addCreditCard.yml
deleted file mode 100644
index 0287f234..00000000
--- a/test/cassettes/referral_customers/addCreditCard.yml
+++ /dev/null
@@ -1,242 +0,0 @@
-
--
-    request:
-        method: GET
-        url: 'https://api.easypost.com/v2/partners/stripe_public_key'
-        headers:
-            Host: api.easypost.com
-            Accept-Encoding: ''
-            Accept: application/json
-            Authorization: ''
-            Content-Type: application/json
-            User-Agent: ''
-    response:
-        status:
-            code: 200
-            message: OK
-        headers:
-            x-frame-options: SAMEORIGIN
-            x-xss-protection: '1; mode=block'
-            x-content-type-options: nosniff
-            x-download-options: noopen
-            x-permitted-cross-domain-policies: none
-            referrer-policy: strict-origin-when-cross-origin
-            x-ep-request-uuid: 7452537966be7d74e78a13210032d5d5
-            cache-control: 'private, no-cache, no-store'
-            pragma: no-cache
-            expires: '0'
-            content-type: 'application/json; charset=utf-8'
-            content-length: '49'
-            x-runtime: '0.024157'
-            x-node: bigweb53nuq
-            x-version-label: easypost-202408151917-1527448f18-master
-            x-backend: easypost
-            x-proxied: ['intlb3nuq c0f5e722d1', 'extlb1nuq b6e1b5034c']
-            strict-transport-security: 'max-age=31536000; includeSubDomains; preload'
-        body: '{"public_key":"pk_x3JSr5eOVWNTLRej8cZDde9VQ0AT5"}'
-        curl_info:
-            url: 'https://api.easypost.com/v2/partners/stripe_public_key'
-            content_type: 'application/json; charset=utf-8'
-            http_code: 200
-            header_size: 687
-            request_size: 303
-            filetime: -1
-            ssl_verify_result: 0
-            redirect_count: 0
-            total_time: 0.237289
-            namelookup_time: 0.006835
-            connect_time: 0.07311
-            pretransfer_time: 0.14141
-            size_upload: 0.0
-            size_download: 49.0
-            speed_download: 206.0
-            speed_upload: 0.0
-            download_content_length: 49.0
-            upload_content_length: 0.0
-            starttransfer_time: 0.237257
-            redirect_time: 0.0
-            redirect_url: ''
-            primary_ip: 169.62.110.131
-            certinfo: {  }
-            primary_port: 443
-            local_ip: 10.130.6.11
-            local_port: 56900
-            http_version: 2
-            protocol: 2
-            ssl_verifyresult: 0
-            scheme: https
-            appconnect_time_us: 141370
-            connect_time_us: 73110
-            namelookup_time_us: 6835
-            pretransfer_time_us: 141410
-            redirect_time_us: 0
-            starttransfer_time_us: 237257
-            total_time_us: 237289
-            effective_method: GET
-            capath: ''
-            cainfo: ''
-    index: 0
--
-    request:
-        method: POST
-        url: 'https://api.stripe.com/v1/tokens?'
-        headers:
-            Host: api.stripe.com
-            Content-Length: '0'
-            Accept-Encoding: ''
-            User-Agent: ''
-            Content-Type: application/x-www-form-urlencoded
-            Authorization: ''
-            Accept: ''
-    response:
-        status:
-            code: 200
-            message: OK
-        headers:
-            Server: nginx
-            Date: 'Thu, 15 Aug 2024 22:13:09 GMT'
-            Content-Type: application/json
-            Content-Length: '788'
-            Connection: keep-alive
-            Access-Control-Allow-Credentials: 'true'
-            Access-Control-Allow-Methods: 'GET,HEAD,PUT,PATCH,POST,DELETE'
-            Access-Control-Allow-Origin: '*'
-            Access-Control-Expose-Headers: 'Request-Id, Stripe-Manage-Version, Stripe-Should-Retry, X-Stripe-External-Auth-Required, X-Stripe-Privileged-Session-Required'
-            Access-Control-Max-Age: '300'
-            Cache-Control: 'no-cache, no-store'
-            Content-Security-Policy: "report-uri https://q.stripe.com/csp-report?p=v1%2Ftokens; block-all-mixed-content; default-src 'none'; base-uri 'none'; form-action 'none'; frame-ancestors 'none'; img-src 'self'; script-src 'self' 'report-sample'; style-src 'self'"
-            Cross-Origin-Opener-Policy-Report-Only: 'same-origin; report-to="coop"'
-            Idempotency-Key: b7950341-1c11-4064-8836-4c9f8d97b88a
-            Original-Request: req_CpQ1fVpRwL3hF1
-            Report-To: '{"group":"coop","max_age":8640,"endpoints":[{"url":"https://q.stripe.com/coop-report?s=payins-bapi-srv"}],"include_subdomains":true}'
-            Reporting-Endpoints: 'coop="https://q.stripe.com/coop-report?s=payins-bapi-srv"'
-            Request-Id: req_CpQ1fVpRwL3hF1
-            Stripe-Should-Retry: 'false'
-            Stripe-Version: '2020-08-27'
-            Vary: Origin
-            X-Content-Type-Options: nosniff
-            X-Stripe-Priority-Routing-Enabled: 'true'
-            X-Stripe-Routing-Context-Priority-Tier: livemode-critical
-            Strict-Transport-Security: 'max-age=63072000; includeSubDomains; preload'
-        body: '{"id":"tok_0PoBurDqT4huGUvdO75MxSbj","object":"token","card":{"id":"card_0PoBurDqT4huGUvdT6xZ1Ast","object":"card","address_city":null,"address_country":null,"address_line1":null,"address_line1_check":null,"address_line2":null,"address_state":null,"address_zip":null,"address_zip_check":null,"brand":"Visa","country":"US","cvc_check":"unchecked","dynamic_last4":null,"exp_month":5,"exp_year":2028,"funding":"credit","last4":"6170","name":null,"networks":{"preferred":null},"tokenization_method":null,"wallet":null},"client_ip":"<REDACTED>","created":1723759989,"livemode":true,"type":"card","used":false}'
-        curl_info:
-            url: 'https://api.stripe.com/v1/tokens?'
-            content_type: application/json
-            http_code: 200
-            header_size: 1459
-            request_size: 298
-            filetime: -1
-            ssl_verify_result: 0
-            redirect_count: 0
-            total_time: 0.477697
-            namelookup_time: 0.031546
-            connect_time: 0.074758
-            pretransfer_time: 0.12075
-            size_upload: 0.0
-            size_download: 788.0
-            speed_download: 1649.0
-            speed_upload: 0.0
-            download_content_length: 788.0
-            upload_content_length: 0.0
-            starttransfer_time: 0.47767
-            redirect_time: 0.0
-            redirect_url: ''
-            primary_ip: 52.26.14.11
-            certinfo: {  }
-            primary_port: 443
-            local_ip: 192.168.1.75
-            local_port: 56901
-            http_version: 2
-            protocol: 2
-            ssl_verifyresult: 0
-            scheme: https
-            appconnect_time_us: 120684
-            connect_time_us: 74758
-            namelookup_time_us: 31546
-            pretransfer_time_us: 120750
-            redirect_time_us: 0
-            starttransfer_time_us: 477670
-            total_time_us: 477697
-            effective_method: POST
-            capath: ''
-            cainfo: ''
-    index: 0
--
-    request:
-        method: POST
-        url: 'https://api.easypost.com/v2/credit_cards'
-        headers:
-            Host: api.easypost.com
-            Expect: ''
-            Accept-Encoding: ''
-            Accept: application/json
-            Authorization: ''
-            Content-Type: application/json
-            User-Agent: ''
-        body: '{"credit_card":{"stripe_object_id":"tok_0PoBurDqT4huGUvdO75MxSbj","priority":"primary"}}'
-    response:
-        status:
-            code: 201
-            message: Created
-        headers:
-            x-frame-options: SAMEORIGIN
-            x-xss-protection: '1; mode=block'
-            x-content-type-options: nosniff
-            x-download-options: noopen
-            x-permitted-cross-domain-policies: none
-            referrer-policy: strict-origin-when-cross-origin
-            x-ep-request-uuid: 7452537966be7d75e78a13230032d663
-            cache-control: 'private, no-cache, no-store'
-            pragma: no-cache
-            expires: '0'
-            content-type: 'application/json; charset=utf-8'
-            content-length: '193'
-            x-runtime: '2.793479'
-            x-node: bigweb33nuq
-            x-version-label: easypost-202408151917-1527448f18-master
-            x-backend: easypost
-            x-proxied: ['intlb3nuq c0f5e722d1', 'extlb1nuq b6e1b5034c']
-            strict-transport-security: 'max-age=31536000; includeSubDomains; preload'
-        body: '{"id":"pm_53cc66088ef3440fbf36fa46964da578","disabled_at":null,"object":"CreditCard","name":null,"last4":"6170","exp_month":5,"exp_year":2028,"brand":"Visa","requires_mandate_collection":false}'
-        curl_info:
-            url: 'https://api.easypost.com/v2/credit_cards'
-            content_type: 'application/json; charset=utf-8'
-            http_code: 201
-            header_size: 693
-            request_size: 398
-            filetime: -1
-            ssl_verify_result: 0
-            redirect_count: 0
-            total_time: 2.996136
-            namelookup_time: 0.00197
-            connect_time: 0.067254
-            pretransfer_time: 0.134764
-            size_upload: 88.0
-            size_download: 193.0
-            speed_download: 64.0
-            speed_upload: 29.0
-            download_content_length: 193.0
-            upload_content_length: 88.0
-            starttransfer_time: 2.996086
-            redirect_time: 0.0
-            redirect_url: ''
-            primary_ip: 169.62.110.131
-            certinfo: {  }
-            primary_port: 443
-            local_ip: 10.130.6.11
-            local_port: 56902
-            http_version: 2
-            protocol: 2
-            ssl_verifyresult: 0
-            scheme: https
-            appconnect_time_us: 134701
-            connect_time_us: 67254
-            namelookup_time_us: 1970
-            pretransfer_time_us: 134764
-            redirect_time_us: 0
-            starttransfer_time_us: 2996086
-            total_time_us: 2996136
-            effective_method: POST
-            capath: ''
-            cainfo: ''
-    index: 0
diff --git a/test/cassettes/referral_customers/retrieveEasypostStripeApiKey.yml b/test/cassettes/referral_customers/retrieveEasypostStripeApiKey.yml
new file mode 100644
index 00000000..3cfe52e5
--- /dev/null
+++ b/test/cassettes/referral_customers/retrieveEasypostStripeApiKey.yml
@@ -0,0 +1,77 @@
+-
+    request:
+        method: GET
+        url: 'https://api.easypost.com/v2/partners/stripe_public_key'
+        headers:
+            Host: api.easypost.com
+            Accept-Encoding: ''
+            Accept: application/json
+            Authorization: ''
+            Content-Type: application/json
+            User-Agent: ''
+    response:
+        status:
+            code: 200
+            message: OK
+        headers:
+            x-frame-options: SAMEORIGIN
+            x-xss-protection: '1; mode=block'
+            x-content-type-options: nosniff
+            x-download-options: noopen
+            x-permitted-cross-domain-policies: none
+            referrer-policy: strict-origin-when-cross-origin
+            x-ep-request-uuid: 91d0a0fa6ab4301ce2b97bb400af2fd1
+            cache-control: 'private, no-cache, no-store'
+            pragma: no-cache
+            expires: '0'
+            content-type: 'application/json; charset=utf-8'
+            content-length: '49'
+            x-runtime: '0.029468'
+            x-node: web103azw
+            x-version-label: easypost-202609231716-41b3efb4ec-main
+            x-backend: easypost
+            x-proxied: ['intlb3azw f29267e751', 'extlb2azw 07fb4d8f06']
+            strict-transport-security: 'max-age=31536000; includeSubDomains; preload'
+        body: '{"public_key":"pk_x3JSr5eOVWNTLRej8cZDde9VQ0AT5"}'
+        curl_info:
+            url: 'https://api.easypost.com/v2/partners/stripe_public_key'
+            content_type: 'application/json; charset=utf-8'
+            http_code: 200
+            header_size: 695
+            request_size: 310
+            filetime: -1
+            ssl_verify_result: 0
+            redirect_count: 0
+            total_time: 0.091
+            namelookup_time: 0.001
+            connect_time: 0.026
+            pretransfer_time: 0.046
+            size_upload: 0.0
+            size_download: 49.0
+            speed_download: 538.0
+            speed_upload: 0.0
+            download_content_length: 49.0
+            upload_content_length: 0.0
+            starttransfer_time: 0.091
+            redirect_time: 0.0
+            redirect_url: ''
+            primary_ip: 169.62.110.130
+            certinfo: {  }
+            primary_port: 443
+            local_ip: 192.168.1.75
+            local_port: 52830
+            http_version: 2
+            protocol: 2
+            ssl_verifyresult: 0
+            scheme: https
+            appconnect_time_us: 46000
+            connect_time_us: 26000
+            namelookup_time_us: 1000
+            pretransfer_time_us: 46000
+            redirect_time_us: 0
+            starttransfer_time_us: 91000
+            total_time_us: 91000
+            effective_method: GET
+            capath: ''
+            cainfo: ''
+    index: 0