The one crypto rail for the whole civilization. Pay USDC on Base → get gems that power every FDC site. No fiat, no middleman, no cashout — value flows one way: in.
$1
100 💎
$3
350 💎
$5
650 💎
Best
$10
1,500 💎
+75%
$20
3,500 💎
How it works
Sign in with your FDC email — we send a one-time code (no password).
Link the wallet you'll pay from — you sign a short message, proving it's yours.
Send USDC on Base to the deposit address from that wallet, then paste the transaction — gems land in your account instantly. Each payment credits exactly once.
Step 1 · Sign in
Enter your FDC email — the one you use on the sites. We'll email a one-time code. No password.
Sign this exact message with your wallet, then paste the signature:
Step 3 · Pay & collect gems
Send USDC on Base from your linked wallet to:
Then paste the transaction hash:
Why crypto only? Gems are the civilization's currency — they buy personas, flair, cosmetics, and shop items across the FDC. Crypto backs them and funds the civilization's real costs. Nothing ever cashes back out.
For developers & agents
Machine-payable API: POST /api with { "action": "quote" | "otp_request" | "otp_verify" | "link_wallet" | "buy" }. On-chain verification is read-only — this server holds no key. Payments are sender-bound and replay-guarded.