I just built a complete airdrop claim interface for the RustChain RIP-305 cross-chain airdrop and wanted to share the technical patterns.
The goal: a zero-dependency claim page that verifies GitHub contributions, connects to both Base L2 (MetaMask) and Solana (Phantom), runs anti-Sybil checks, and lets eligible users claim wrapped RTC tokens.
Here's what I learned.
The Stack
Vanilla HTML/CSS/JS. No React. No build step. No bundler.
Why? Airdrop claim pages need to be:
Auditable — users need to inspect what runs in their browser
Fast — no 3MB React bundle
Deployable anywhere — IPFS, GitHub Pages, raw CDN
A single index.html file is the right call.
GitHub OAuth Flow
The eligibility check needs to verify:
- How many repos the user has starred (Stargazer tier)
- How many PRs they've had merged (Contributor/Builder/Core tiers)
- Account age (>30 days anti-Sybil)
In production, this requires a server-side OAuth callback:
// Frontend: redirect to OAuth
window.location.href = '/api/auth/github?redirect=/airdrop';
// Server: exchange code for token, fetch GitHub API
const ghUser = await fetch('https://api.github.com/user', {
headers: { Authorization: `token ${access_token}` }
}).then(r => r.json());
const prs = await fetch(
`https://api.github.com/search/issues?q=is:pr+is:merged+author:${ghUser.login}+repo:Scottcjn/Rustchain`,
{ headers: { Authorization: `token ${access_token}` } }
).then(r => r.json());
The server returns a session with tier data. No GitHub tokens ever touch the client.
MetaMask (Base L2) Connection
Base is EVM-compatible, so MetaMask works with window.ethereum:
async function connectMetaMask() {
// Request accounts
const accounts = await window.ethereum.request({
method: 'eth_requestAccounts'
});
// Switch to Base (chain ID 8453 = 0x2105)
try {
await window.ethereum.request({
method: 'wallet_switchEthereumChain',
params: [{ chainId: '0x2105' }]
});
} catch (err) {
if (err.code === 4902) {
// Chain not added yet — add it
await window.ethereum.request({
method: 'wallet_addEthereumChain',
params: [{
chainId: '0x2105',
chainName: 'Base',
rpcUrls: ['https://mainnet.base.org'],
nativeCurrency: { name: 'ETH', symbol: 'ETH', decimals: 18 },
blockExplorerUrls: ['https://basescan.org']
}]
});
}
}
// Get ETH balance
const balanceHex = await window.ethereum.request({
method: 'eth_getBalance',
params: [accounts[0], 'latest']
});
const balanceETH = parseInt(balanceHex, 16) / 1e18;
}
The wallet_switchEthereumChain + wallet_addEthereumChain combo handles both existing and new Base configurations.
Phantom (Solana) Connection
Phantom exposes window.solana:
async function connectPhantom() {
const phantom = window.solana;
if (!phantom?.isPhantom) {
throw new Error('Phantom not installed');
}
const resp = await phantom.connect();
const pubkey = resp.publicKey.toString();
// Fetch SOL balance via JSON-RPC (no SDK needed)
const rpcResp = await fetch('https://api.mainnet-beta.solana.com', {
method: 'POST',
headers: { 'Content-Type': 'application/json' },
body: JSON.stringify({
jsonrpc: '2.0',
id: 1,
method: 'getBalance',
params: [pubkey, { commitment: 'confirmed' }]
})
});
const data = await rpcResp.json();
const balanceSOL = data.result.value / 1e9; // lamports → SOL
}
No @solana/web3.js needed. The JSON-RPC call works directly.
Anti-Sybil Checks
The RIP-305 spec requires:
| Check | Implementation |
|---|---|
| Wallet age > 7 days | Fetch first tx from Etherscan/Solana RPC |
| GitHub account > 30 days | created_at from GitHub API |
| Min 0.01 ETH or 0.1 SOL | Balance check in wallet connection |
| One claim per GitHub | Session dedup in backend DB |
| One claim per wallet | Wallet address dedup in DB |
For wallet age on Base:
// Get first transaction (oldest = wallet creation)
const txResp = await fetch(
`https://api.basescan.org/api?module=account&action=txlist` +
`&address=${address}&sort=asc&page=1&offset=1&apikey=${BASESCAN_KEY}`
);
const txData = await txResp.json();
const firstTxTime = txData.result[0]?.timeStamp;
const ageInDays = (Date.now()/1000 - firstTxTime) / 86400;
For Solana:
// Get oldest confirmed signature
const sigResp = await fetch('https://api.mainnet-beta.solana.com', {
method: 'POST',
body: JSON.stringify({
jsonrpc: '2.0', id: 1,
method: 'getSignaturesForAddress',
params: [pubkey, { limit: 1, before: null }]
})
});
Eligibility Tiers + Multipliers
The RIP-305 tiering is straightforward to implement:
function computeAllocation(stars, prs, walletBalance, walletType) {
// Tier determination
let tier, baseClaim;
if (prs >= 5) { tier = 'Core'; baseClaim = 200; }
else if (prs >= 3) { tier = 'Builder'; baseClaim = 100; }
else if (prs >= 1) { tier = 'Contributor'; baseClaim = 50; }
else if (stars >= 10) { tier = 'Stargazer'; baseClaim = 25; }
else { return { tier: 'None', baseClaim: 0, total: 0 }; }
// Wallet multiplier
let multiplier = 1.0;
if (walletType === 'eth') {
if (walletBalance >= 1) multiplier = 2.0;
else if (walletBalance >= 0.1) multiplier = 1.5;
} else { // SOL
if (walletBalance >= 10) multiplier = 2.0;
else if (walletBalance >= 1) multiplier = 1.5;
}
return { tier, baseClaim, multiplier, total: Math.round(baseClaim * multiplier) };
}
UX Patterns for Multi-Step Flows
The claim flow has 5 steps. I used a simple progressive disclosure pattern:
function unlockStep(n) {
const num = document.getElementById(`step${n}-num`);
const content = document.getElementById(`step${n}-content`);
num.style.opacity = '1';
content.style.opacity = '1';
// Enable buttons in this step
content.querySelectorAll('button, input').forEach(el => el.disabled = false);
}
Each step completion triggers unlockStep(n+1). No state machine library needed.
Deployment
A single index.html can be:
IPFS via Pinata:pinata upload index.html→ immutable hash, permanently accessible
GitHub Pages: push togh-pagesbranch, enable in repo settings
Cloudflare Pages: connect repo, auto-deploy on push
Vercel:vercel deploy --prod
For IPFS, the GitHub OAuth callback needs to be a separate serverless function (Vercel, Cloudflare Workers, etc.) since IPFS can't run server code.
Full Source
The complete implementation (HTML + README) is in the RustChain PR #678.
Total lines: ~700. Total dependencies: 0.
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