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The Compatibility API lets an existing merchant integration keep its provider SDK and request format while switching traffic to PawPayments. In most integrations, the merchant changes only the provider base URL:
Provider SDKPaw base URL
Cryptomushttps://api.pawpayments.com/compat/cryptomus/v1
Helekethttps://api.pawpayments.com/compat/heleket/v1
NowPaymentshttps://api.pawpayments.com/compat/nowpayments/v1
CoinPayments (legacy v1)https://api.pawpayments.com/compat/coinpayments/v1/api.php
CoinPayments (v2 REST)https://api.pawpayments.com/compat/coinpayments
Use the same Paw merchant api_key for request signing. Cryptomus and Heleket SDKs send the Paw merchant ID as the merchant header and sign with api_key. NowPayments SDKs continue to send x-api-key. CoinPayments SDKs send the api_key as the key/client id and sign with it (HMAC-SHA512 for legacy, HMAC-SHA256 for v2).

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Where to change the base URL

You only repoint the SDK (or your HTTP client) at the Paw compat base URL — paths, headers, request signing, and response parsing stay exactly the same. Below is the exact place to change it for each provider’s official SDK. If you call the REST API directly without an SDK, just swap the scheme + host (keeping the version prefix) for the Paw base URL.

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Cryptomus / Heleket

Default host: https://api.cryptomus.com/ (Heleket: https://api.heleket.com/). The SDK appends v1/payment, v1/payout, etc.
  • Official PHP SDK (cryptomus/api-php-sdk): edit the constant in src/RequestBuilder.php: 
    // const API_URL = "https://api.cryptomus.com/";
const API_URL = "https://api.pawpayments.com/compat/cryptomus/"; // Heleket: .../compat/heleket/
  • Other SDKs / raw REST: set the API host so requests resolve to https://api.pawpayments.com/compat/cryptomus/v1/... (or .../compat/heleket/v1/...).
Keep the merchant header (Paw merchant id) and sign (md5(base64(json_body) + api_key)) unchanged.

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NowPayments

Default base: https://api.nowpayments.io/v1/.
  • Official PHP SDK (nowpayments-api-php): change the class constant: 
    // const API_BASE = 'https://api.nowpayments.io/v1/';
const API_BASE = 'https://api.pawpayments.com/compat/nowpayments/v1/';
  • JavaScript / Go / other: set the base-URL / host option to https://api.pawpayments.com/compat/nowpayments/v1.
Keep sending x-api-key. The payout JWT flow (POST /v1/auth) works unchanged against the same base URL.

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CoinPayments — legacy v1 (api.php)

Legacy SDKs post to a single full URL, https://www.coinpayments.net/api.php.
  • Set the SDK’s API URL field/constant (e.g. $this->url / API_URL in the CoinPayments PHP class) to: 
    https://api.pawpayments.com/compat/coinpayments/v1/api.php
Keep the public key POST field and the HMAC header (HMAC-SHA512 of the raw body) unchanged.

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CoinPayments — v2 (REST)

Default base: https://a-api.coinpayments.net (the SDK appends /api/v2/merchant/...).
  • Pass the base URL to the client constructor — without a trailing path: 
    # Python (CoinPaymentsNet/sdk)
client = CoinPaymentsClient(client_id, client_secret,
                            base_url="https://api.pawpayments.com/compat/coinpayments")
    PHP/JS equivalents set the same value (e.g. ApiHelper::API_URL).
Use exactly https://api.pawpayments.com/compat/coinpayments (no extra path): the v2 signature covers the full request URL, so the base must match what Paw reconstructs.

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Webhooks

Invoices created through a compatibility route automatically use that provider’s webhook format:
Created throughWebhook format
/compat/cryptomus/v1Cryptomus IPN body with sign in JSON
/compat/heleket/v1Heleket-compatible IPN body with sign in JSON
/compat/nowpayments/v1NowPayments IPN body with x-nowpayments-sig header
/compat/coinpayments/v1CoinPayments IPN, form-encoded body + HMAC header (HMAC-SHA512)
/compat/coinpayments/api/v2CoinPayments v2 JSON body + X-CoinPayments-Signature header (HMAC-SHA256)
Native APINative format by default, or the invoice-level webhook_format override
Compatibility routes are documented here as a migration guide. For individual request field descriptions, keep using the original provider documentation. The sections below describe what Paw supports, what is ignored, and what returns 501 NOT_SUPPORTED.