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Payra Python SDK

Official Python SDK for integrating Payra's on-chain payment system into your backend applications.

This SDK provides:

  • Secure generation of ECDSA signatures compatible with the Payra smart contract, used for order payment verification.
  • Simple methods for checking the on-chain details of orders to confirm completed payments.

How It Works

The typical flow for signing and verifying a Payra transaction:

  1. The frontend prepares all required payment parameters:
  • Network – blockchain name (e.g. Polygon, Linea)
  • Token address – ERC-20 token contract address
  • Order ID – unique order identifier
  • Amount WEI – already converted to the smallest unit (e.g. wei, 10⁶)
  • Timestamp – Unix timestamp of the order
  • Payer wallet address – the wallet address from which the user will make the on-chain payment
  1. The frontend sends these parameters to your backend.
  2. The backend uses this SDK to generate a cryptographic ECDSA signature with its signature key (performed offline).
  3. The backend returns the generated signature to the frontend.
  4. The frontend calls the Payra smart contract (payOrder) with all parameters plus the signature.

This process ensures full compatibility between your backend and Payra’s on-chain verification logic.

Features

  • Generates Ethereum ECDSA signatures using the secp256k1 curve.
  • Fully compatible with Payra's Solidity smart contracts (ERC-1155 payment verification).
  • Supports .env and config/payra.php configuration for multiple blockchain networks.
  • Laravel IoC container integration (easy dependency injection)
  • Verifies order payment details directly on-chain via RPC or blockchain explorer API.
  • Provides secure backend integration for signing and verifying transactions.
  • Includes optional utility helpers for:
  • Currency conversion (via ExchangeRate API)
  • USD ⇄ WEI conversion for token precision handling.

Setup

Before installing this package, make sure you have an active Payra account:

https://payra.cash/products/on-chain-payments/registration

Before installing this package, make sure you have a MerchantID

  • Your Merchant ID (unique for each blockchain network)
  • Your Signature Key (used to sign Payra transactions securely)

Additionally: To obtain your RPC URLs which are required for reading on-chain order statuses directly from the blockchain, you can use the public free endpoints provided with this package or create an account on one of the following services for better performance and reliability:

  • QuickNode – Extremely fast and excellent for Polygon/Mainnet. (quicknode.com)

  • Alchemy – Offers a great developer dashboard and high reliability. (alchemy.com)

  • DRPC – Decentralized RPC with a generous free tier and a strict no-log policy. (drpc.org)

  • Infura – The industry standard; very stable, especially for Ethereum. (infura.io)

Optional (recommended):

  • Create a free API key at ExchangeRate API to enable automatic fiat → USD conversions using the built-in utility helpers.

Installation

From PyPI

Install the latest stable version from PyPI:

pip  install  payra-sdk

From Source (for development)

Clone and install locally (editable mode for development):

git clone https://github.com/payracash/payra-sdk-python.git
cd payra-sdk-python
python3 -m venv venv
source venv/bin/activate  # Windows: venv\Scripts\activate
pip install -e .

Dependencies

This SDK requires:

  • Python 3.8+
  • web3.py
  • ecdsa
  • python-dotenv
  • (optional) requests and exchange-rate-api for fiat conversion utilities.

Environment Configuration

Create a .env file in your project root (you can copy from example):

cp  .env.example  .env

This file stores your private configuration and connection settings for all supported networks. Never commit .env to version control.

Required Variables

Exchange Rate (optional)

Used for automatic fiat → USD conversions via the built-in Payra utilities.

# Optional only needed if you want to use the built-in currency conversion helper
PAYRA_EXCHANGE_RATE_API_KEY= # Your ExchangeRate API key (from exchangerate-api.com)
PAYRA_EXCHANGE_RATE_CACHE_TIME=720  # Cache duration in minutes (default: 720 = 12h)

PAYRA_POLYGON_OCP_GATEWAY_CONTRACT_ADDRESS=0xc56c55D9cF0FF05c85A2DF5BFB9a65b34804063b
PAYRA_POLYGON_SIGNATURE_KEY=
PAYRA_POLYGON_MERCHANT_ID=
PAYRA_POLYGON_RPC_URL_1=https://polygon-rpc.com
PAYRA_POLYGON_RPC_URL_2=

PAYRA_ETHEREUM_OCP_GATEWAY_CONTRACT_ADDRESS=
PAYRA_ETHEREUM_SIGNATURE_KEY=
PAYRA_ETHEREUM_MERCHANT_ID=
PAYRA_ETHEREUM_RPC_URL_1=
PAYRA_ETHEREUM_RPC_URL_2=

PAYRA_LINEA_OCP_GATEWAY_CONTRACT_ADDRESS=
PAYRA_LINEA_SIGNATURE_KEY=
PAYRA_LINEA_MERCHANT_ID=
PAYRA_LINEA_RPC_URL_1=
PAYRA_LINEA_RPC_URL_2=

Important Notes

  • The cache automatically refreshes when it expires.
  • You can adjust the cache duration by setting PAYRA_EXCHANGE_RATE_CACHE_TIME:
    • 5 → cache for 5 minutes
    • 60 → cache for 1 hour
    • 720 → cache for 12 hours (default)
  • Each network (Polygon, Ethereum, Linea) has its own merchant ID, signature key, and RPC URLs.
  • The SDK automatically detects which chain configuration to use based on the selected network.
  • You can use multiple RPC URLs for redundancy (the SDK will automatically fall back if one fails).
  • Contract addresses correspond to the deployed Payra Core Forward contracts per network.

Usage Example

Generating signature

from payra_sdk import PayraUtils, PayraSignature, PayraSDKException

try:
	# Convert amount to smallest unit (wei or token decimals
	amount_wei = PayraUtils.to_wei(3.34, 'polygon', 'usdt')
	
	PAYMENT_DATA = {
		"network": "polygon",
		"tokenAddress": "0xc2132D05D31c914a87C6611C10748AEb04B58e8F", # USDT on Polygon
		"orderId": "ord-258",
		"amountWei": amount_wei, # e.g. 3.34 USDT in smallest unit
		"timestamp": 1753826059, # current Unix timestamp
		"payerAddress": "0xe6c961D6ad9a27Ea8e5d99e40abaC365DE9Cc162"
	}
	
	# Initialize signer
	payra_signature = PayraSignature()
	
	# Generate cryptographic signature
	signature = payra_signature.generate(
		network=PAYMENT_DATA["network"],
		token_address=PAYMENT_DATA["tokenAddress"],
		order_id=PAYMENT_DATA["orderId"],
		amount_wei=PAYMENT_DATA["amountWei"],
		timestamp=PAYMENT_DATA["timestamp"],
		payer_address=PAYMENT_DATA["payerAddress"]
	)
	
	print(f"Generated signature: {signature}")
except PayraSDKException as e:
	print(f"Payra SDK error: {e}")
except  Exception  as e:
	print(f"Unexpected error: {e}")

Input Parameters

Field Type Description
network string Selected network name
tokenAddress string ERC20 token contract address
orderId string Unique order reference (e.g. ORDER-123)
amountWei string or integer Token amount in smallest unit (e.g. wei)
timestamp number Unix timestamp of signature creation
payerAddress string Payer Wallet Address

Behind the Scenes

  1. The backend converts the amount to the smallest blockchain unit (e.g. wei).
  2. A PayraSignature instance is created using your signature key from .env
  3. It generates an ECDSA signature that is fully verifiable on-chain by the Payra smart contract.
  4. The resulting signature should be sent to the frontend, which must call payOrder(...) using the same parameters (timestamp, orderId, amount, tokenAddress, etc.) that were used to generate the signature.

Get Order Details

Retrieve full payment details for a specific order from the Payra smart contract. This method returns the complete on-chain payment data associated with the order, including:

  • whether the order has been paid,
  • the payment token address,
  • the paid amount,
  • the fee amount,
  • and the payment timestamp.

Use this method when you need detailed information about the payment or want to display full transaction data.

from payra_sdk import PayraOrderService, PayraSDKException

try:
	ORDER_ID = "ord-258"
	# Initialize verifier for a specific network
	order_service = PayraOrderService("polygon")
	
	print("\nGet order details...")
	details = order_service.get_details(ORDER_ID)
	
	print("Order ID:", ORDER_ID)
	print("Details:", details)
	        
except PayraSDKException as e:
	print(f"Payra SDK error: {e}")
except  Exception  as e:
	print(f"Unexpected error: {e}")

Behind the Scenes

  1. The backend initializes a PayraOrderService object for the desired blockchain network.
  2. It calls get_details(order_id) to get transaction details from blockchain.
  3. The function returns a dictionary with:
{
	"success": True,
	"paid": True,
	"error": None,
	"toke": '0xc2132d05d31c914a87c6611c10748aeb04b58e8f',
	"amount": 400000,
	"fee": 3600,
	"timestamp": 1765138941
}

Check Order Paid Status

Perform a simple payment check for a specific order. This method only verifies whether the order has been paid (true or false) and does not return any additional payment details.

Use this method when you only need a quick boolean confirmation of the payment status.

from payra_sdk import PayraOrderService, PayraSDKException

try:
	ORDER_ID = "ord-258"

	# Initialize verifier for a specific network
	order_service = PayraOrderService("polygon")

	print("\nChecking order status...")
	result = order_service.is_paid(ORDER_ID)

	print("Order ID:", ORDER_ID)
	print("Result:", result)

	if result["success"] and result["paid"]:
		print("Order is PAID on-chain")
	elif result["success"]:
		print("Order is NOT paid yet")
	else:
		print("Error:", result["error"])
		
except PayraSDKException as e:
	print(f"Payra SDK error: {e}")
except  Exception  as e:
	print(f"Unexpected error: {e}")

Behind the Scenes

  1. The backend initializes a PayraOrderService object for the desired blockchain network.
  2. It calls is_paid(order_id) to check if the order transaction exists and is confirmed on-chain.
  3. The function returns a dictionary with:
{
	"success": True,
	"paid": True,
	"error": None
}
  1. If paid is True, the order has been successfully processed and confirmed by the Payra smart contract.

Using Utility Functions

The PayraUtils module provides convenient helpers for token conversion, precision handling, and fiat currency operations.

from payra_sdk import PayraUtils

# Convert USD/token amount to smallest unit (Wei or token decimals)
amount_wei = PayraUtils.to_wei(3.34, 'polygon', 'usdt')
print("Amount in Wei:", amount_wei) # 3340000

# Convert from Wei back to readable token amount
amount = PayraUtils.from_wei(3340000, 'polygon', 'usdt', precision=2)
print("Readable amount:", amount) # "3.34"

# Get token decimals for any supported network
print("USDT decimals on Polygon:", PayraUtils.get_decimals("polygon", "usdt"))
print("POL decimals on Polygon:", PayraUtils.get_decimals("polygon", "pol"))

# Convert fiat currency to USD using the built-in ExchangeRate API
usd_value = PayraUtils.convert_to_usd(100, "EUR")
print(f"100 EUR = {usd_value} USD")

Behind the Scenes

  • to_wei(amount, network, token) – Converts a human-readable token amount into the smallest unit (used on-chain).
  • from_wei(amount, network, token, precision) – Converts back from smallest unit to a formatted amount.
  • get_decimals(network, token) – Returns the number of decimals for the given token on that network.
  • convert_to_usd(amount, currency) – Converts fiat amounts (e.g. EUR, GBP) to USD using your ExchangeRate API key.

Testing

You can run the included examples to test signing and verification:

python3 example_signature.py
python3 example_order_get_details.py
python3 example_order_is_paid.py
python3 example_utils.py

Make sure your .env file contains correct values for the network being used.

Security Notice

Never expose your signature key in frontend or client-side code.
This SDK is server-side only and must be used securely on your backend. Never use it in frontend or browser environments. Also, never commit your .env file to version control.

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MIT © Payra

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