Introduction

Create, store, and verify location attestations on any blockchain.

Astral SDK is a developer-friendly TypeScript library that makes location-based attestations simple. Built on Ethereum Attestation Service (EAS), it supports both gasless offchain signatures and permanent onchain registration across multiple networks.

Quick Navigation

Getting Started

• Core Concepts - Key terminology and concepts
• Quick Start - 30-second example
• Getting Started Guide - Complete tutorial

Workflows

• Offchain Workflow - Gasless EIP-712 signatures
• Onchain Workflow - Permanent blockchain records

Reference

• SDK API Reference - Complete method documentation
• Extensions Guide - Extension system overview

Why Astral SDK?

Two ways to create location attestations

• Offchain: Gasless EIP-712 signatures, instant verification
• Onchain: Permanent blockchain registration with smart contract integration

Supported location formats

• GeoJSON (Points, Polygons, Features) - ■ Available now
• Decimal coordinates [lng, lat] - □ Coming soon
• Well-Known Text (WKT) - □ Coming soon
• H3 geospatial indexing - □ Coming soon

Multi-chain ready

• Sepolia (testnet) • Base • Arbitrum • Celo

Developer experience

• 100% TypeScript with full type safety
• Clear workflow separation (no confusion)
• Comprehensive docs and working examples

Installation

pnpm add @decentralized-geo/astral-sdk  # or npm/yarn

30-Second Example

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

// Connect to your wallet
const sdk = new AstralSDK({
  provider: window.ethereum,
  defaultChain: "sepolia",
});

// Create a location attestation
const attestation = await sdk.createOffchainLocationAttestation({
  location: [-0.163808, 51.5101], // London coordinates
  memo: "Visited Big Ben today!",
});

// ✅ Done! You have a cryptographically signed location attestation
console.log("Attestation UID:", attestation.uid);

What's Next?

1. New to location attestations? Start with Core Concepts
2. Want to build something? Try the Getting Started Guide