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First Attestation

Create and verify your first location attestation.

Offchain Attestation (No Gas)​

Start with an offchain attestation - no blockchain fees required:

import { AstralSDK } from '@decentralized-geo/astral-sdk';

// Initialize SDK
const sdk = new AstralSDK({ 
  provider: window.ethereum,
  defaultChain: 'sepolia' 
});

// Create attestation
const attestation = await sdk.createOffchainLocationAttestation({
  location: [-0.163808, 51.5101], // [lng, lat]
  memo: 'Westminster Bridge, London'
});

console.log('Created attestation:', attestation.uid);
console.log('Signed by:', attestation.signer);

Verify the Attestation​

// Verify signature
const verification = await sdk.verifyOffchainLocationAttestation(attestation);

console.log('Valid signature:', verification.isValid);
console.log('Signer address:', verification.signer);
console.log('Location data:', verification.locationData);

Understanding the Response​

An offchain attestation contains:

{
  uid: "0x...",           // Unique identifier
  signer: "0x...",        // Wallet that signed
  signature: "0x...",     // EIP-712 signature
  locationData: {...},    // Your location data
  timestamp: 1234567890,  // Unix timestamp
  memo: "..."            // Your memo text
}

Try Different Locations​

GeoJSON Point​

const pointAttestation = await sdk.createOffchainLocationAttestation({
  location: {
    type: 'Point',
    coordinates: [139.6503, 35.6762] // Tokyo
  },
  memo: 'Tokyo Tower observation'
});

GeoJSON Feature​

const featureAttestation = await sdk.createOffchainLocationAttestation({
  location: {
    type: 'Feature',
    properties: { 
      name: 'Eiffel Tower',
      height: 330 
    },
    geometry: {
      type: 'Point',
      coordinates: [2.2945, 48.8584] // Paris
    }
  },
  memo: 'Landmark documentation'
});

What's Next?​

✓ You've created your first location attestation!

→ Continue Learning​

• Offchain Workflow Guide - Deep dive into offchain attestations • Onchain Workflow Guide - Create permanent blockchain records • Core Concepts - Understand the fundamentals

→ Build Something​

• Environmental monitoring station • Delivery confirmation system • Location-based rewards • Geospatial data registry

→ Get Help​

• Review common issues • Check the API Reference • See example projects