Can I expose any smart contract as a REST API?

Yes. Any smart contract on any EVM-compatible chain (Ethereum, Base, Polygon, Arbitrum, etc.) can be exposed as a REST API through Opsalis. You write a thin wrapper that reads from the contract and returns JSON.

Do consumers need Web3 libraries or a crypto wallet?

No. Consumers make standard REST API calls with JSON. The owner's wrapper handles all blockchain interaction. Consumers never need MetaMask, ethers.js, or any Web3 tooling.

How is pricing handled for smart contract API calls?

The API owner sets per-call pricing in USDC. Each call is settled on Base L2 with a 5% platform fee. Owners receive 95% of each call's price.

Smart Contract as API — On-Chain Data via REST

How It Works

Consumer makes a standard REST call. The owner's wrapper reads from a Chainlink price feed on Base Sepolia and returns the data as JSON.

Why Smart Contract APIs?

Billions of dollars in DeFi data live on-chain, but accessing it requires blockchain-specific tooling — RPC providers, ABI parsing, hex decoding. Most developers just want a REST endpoint that returns JSON. Opsalis makes that possible.

Expose any smart contract as a REST API. DeFi data, NFT metadata, governance votes — all accessible via simple HTTP calls. The owner's wrapper reads from the blockchain and returns clean JSON. Consumers never need to install Web3 libraries or manage RPC connections.

Real-world example: a financial dashboard pulls ETH/USD prices from a Chainlink price feed registered on Opsalis. One REST call, one JSON response, settled in USDC — no Ethereum node required on the consumer side.

Live Demo — Call a Smart Contract via REST

Chainlink Price Feed Query

Contract Function

Trading Pair

Chain

Click "Run Demo" to call the smart contract via REST and see the on-chain price data returned as JSON.

Code Samples

curl -X POST https://opsalis.com/api/demo/api/bb-smart-contract \
  -H "Content-Type: application/json" \
  -H "X-Consumer-Key: demo-public-key-2026" \
  -d '{
    "function": "getLatestPrice",
    "pair": "ETH/USD",
    "chain": 84532
  }'

const response = await fetch('https://opsalis.com/api/demo/api/bb-smart-contract', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'X-Consumer-Key': 'demo-public-key-2026'
  },
  body: JSON.stringify({
    function: 'getLatestPrice',
    pair: 'ETH/USD',
    chain: 84532
  })
});

const data = await response.json();
console.log('ETH/USD Price:', data.price);
console.log('Block:', data.blockNumber);

import requests

response = requests.post(
    'https://opsalis.com/api/demo/api/bb-smart-contract',
    headers={
        'Content-Type': 'application/json',
        'X-Consumer-Key': 'demo-public-key-2026'
    },
    json={
        'function': 'getLatestPrice',
        'pair': 'ETH/USD',
        'chain': 84532
    }
)

data = response.json()
print(f"ETH/USD Price: {data['price']}")
print(f"Block: {data['blockNumber']}")

Self-Host: Expose Your Own Smart Contract

Install Opsalis

Pull the free Docker container onto your own server. No cloud dependency.

docker pull opsalis/control-center:latest
docker run -d --name opsalis -p 3000:3000 opsalis/control-center:latest

Create a Contract Wrapper

Write a thin wrapper that reads from your smart contract via RPC and returns JSON. Point it at any EVM chain — Ethereum, Base, Polygon, Arbitrum.

# Example: Node.js wrapper reading Chainlink price feed
# Your wrapper exposes a REST endpoint that Opsalis routes to
node contract-wrapper.js --chain base-sepolia --contract 0x...

Register Your API

Open the Opsalis web console and register your wrapper endpoint. Set per-call pricing in USDC.

# In the Opsalis web console:
# 1. Go to APIs → Register New API
# 2. Set endpoint: http://localhost:8080/price-feed
# 3. Set price: 0.001 USDC per call
# 4. Enable on the marketplace

Go Live

Your smart contract data is now available as a REST API on the Opsalis marketplace. Consumers call it with standard HTTP — no Web3 required on their side.

Smart Contract as API